QCU/DES/USMLE/INFECTIOUS

1. A 36-year-old woman who lives in the suburbs of a large city comes to your office for a tuberculin skin test. She will be volunteering in her daughter's school cafeteria and the school district requires tuberculin testing. You inject a small amount of Mycobacterium tuberculosis purified protein derivative (PPD) in the skin and 2 days later she returns for a reading. You measure 12 mm of induration. She reports no history of tuberculosis exposure and no underlying medical conditions. She has never before been tested for tuberculosis. She was born in the United States, is not a healthcare worker, and has never spent time in prison. What is the best next step in her management

2. A 22-year-old male student presents with an acute onset of fever, double vision, and painful swelling around his eyes. He also has significant muscle pain in his neck and jaw muscles. A week earlier, he experienced a period of abdominal pain, nausea, vomiting, and diarrhea, all of which resolved spontaneously. He has a history of intravenous drug abuse but has recently completed of a drug rehabilitation program. He is febrile. Physical examination shows "splinter" hemorrhages, periorbital edema, and chemosis. Chest is clear to auscultation. Cardiac exam reveals no murmur. Abdomen is soft and nontender with no organomegaly. His complete blood count is shown below: Hemoglobin 13.0 g/L MCV 85 fl Platelets 228,000/mm3 Leukocyte count 10,500/mm3 Neutrophils 56% Eosinophils 21% Lymphocytes 23% Based on these findings, what is the most likely diagnosis?

3. A 55-year-old pig farmer is brought to the emergency department (ED) after having a seizure two hours ago. During his transit to the ED, he has another seizure. On arrival, he is unconscious, pulseless, and not breathing. Resuscitation is successful and the patient is stabilized; however, he does not do well over the next several days and is eventually declared dead. His wife says that he had been healthy most of his life, except for the past few weeks, when he was complaining of headaches. Autopsy shows multiple fluid-filled cysts in the brain parenchyma. Which of the following is the most likely diagnosis of this patient?

4. A 12-year-old boy is brought to the emergency department because of severe pain near his left knee. He has sickle cell disease, and has been hospitalized previously for sickle cell crisis. Vital signs are notable for mild fever. Examination of the left lower extremity reveals a normal knee joint with marked tenderness and swelling over the proximal tibia. Labs show leukocytosis and elevated ESR. He is subsequently diagnosed with osteomyelitis. Which of the following organisms is the most likely cause of his condition?

5. A 55-year-old man has undergone renal transplantation due to end-stage renal failure. His postoperative course was uncomplicated. He is currently taking prednisone and cyclosporine. He is afebrile and his pulse is 80/min, respirations are 14/min, and blood pressure is 130/65 mm Hg. Physical examination is unremarkable. Which of the following should be added to his current medication regimen to prevent opportunistic infections?

6. A 23-year-old male comes to ER with five-day history of diarrhea and abdominal pain. Initially, the diarrhea was watery occurring five-six times per day but yesterday he noticed blood in the stool which prompted his visit to ER. He describes his abdominal pain as colicky and severe. He also complains of nausea and decreased appetite but he has had no vomiting. His past medical history is insignificant and never had similar symptoms. He is not sexually active and he denies any illicit drug use. He has no history of recent travel. His father had colon cancer and his uncle died of liver cirrhosis. His temperature is 36.6C (98.0F), blood pressure is 123/82 mmHg and heart rate is 102/min. On examination, he has prominent periumbilical and right lower quadrant tenderness but no guarding or rebound. Rectal examination reveals brownish stool mixed with blood. Which of the following is the most likely diagnosis?

7. A 24-year-old man is found to be HIV positive. He is asymptomatic. Physical examination is unremarkable. Laboratory tests show: CD4 count 400/micro-L HIV viral load 9,000 copies/mL VDRL negative Toxoplasma serology negative PPD test 6mm induration His chest x-ray is unremarkable. What is the most appropriate next step in the management of this patient?

8. A very worried 25-year-old woman comes to the office, presents a positive pregnancy test, and says, "I'm six weeks pregnant. Two months ago, I received the rubella vaccine and my doctor told me to avoid getting pregnant for the next three months. I'm very concerned about the health of my unborn baby. I'd like to know all the available options to prevent any harm to my baby." What is the most appropriate next step in the management of this patient?

9. A 65-year-old man presents to the emergency department with a two-day history of fever, headache, altered mental status, and vomiting. His past medical history is significant for renal transplantation secondary to polycystic kidney disease, hypertension, and diabetes. He takes aspirin, insulin, nifedipine, cyclosporine, and prednisone. He has no known drug allergies. His temperature is 39.2C (102.5F), pulse is 102/min, respirations are 18/min, and blood pressure is 120/75 mm Hg. He is alert but confused. Fundoscopy does not show any abnormalities. His neck is stiff. Lungs are clear to auscultation. He has a normal S1 and S2 with a II/IV systolic ejection murmur heard best in the right infraclavicular area. Complete blood count shows a WBC count of 17,000/cm3 with neutrophilic leukocytosis. His blood is drawn and sent for culture. Lumbar puncture is performed and the results are pending. Which of the following is the most appropriate empiric antibiotic therapy for this patient?

10. A 30-year-old male has recently been diagnosed with HIV infection. He denies drug abuse. He is currently asymptomatic, and physical examination is unremarkable. He is in a stable heterosexual relationship. Laboratory studies show a CD4 count of 350/microL, HIV viral load of 15,000 copies/mL, negative VDRL, negative toxoplasma serology, tuberculin skin test of 7 mm induration, negative HBsAg, and positive anti-HBsAg antibodies. Hepatitis C antibodies are negative. Complete blood count, serum chemistries, and liver function tests are within normal limits. He has not received any vaccinations since being diagnosed with HIV. Which of the following vaccines is indicated in this patient?

11. A 60-year-old Caucasian woman undergoes elective coronary artery bypass surgery and aortic valve replacement. Her postoperative course is complicated by acute renal failure, atrial fibrillation, and pulmonary edema. On the third postoperative day, extubation is attempted but not tolerated, thus warranting reintubation. On the fifth postoperative day, she develops a fever to 38.9 C (102 F). Her pulse is 110-120/min and irregular, respirations are 36/min, and blood pressure is 110/65 mmHg. Her chest x-ray shows right middle and lower lobe infiltrates. WBC count is elevated with bandemia. Gram stain of her sputum shows gram-negative rods. She is given intravenous ceftriaxone; however, she deteriorates over the next 24 hours. Which of the following is the most appropriate next step in the management of this patient?

12. A 42-year-old man with advanced HIV infection has a two-week history of pain and difficulty with swallowing. He was given fluconazole for these symptoms one week ago, but his pain has worsened. His current medications include tenofovir, emtricitabine, efavirenz, and trimethoprim- sulfamethoxazole. His CD4 count is 90/microl and viral load is 300,000copies/ml. Endoscopy reveals large, irregular, linear ulcers in the esophagus. A biopsy of the abnormal mucosa reveals tissue destruction and the presence of intranuclear and intracytoplasmic inclusions. Which of the following is the most appropriate pharmacotherapy for this patient?

13. A 26-year-old man presents to the physician's office with a two-day history of multiple symptoms, including rash on his trunk, headache, fatigue, malaise, myalgias, and high-grade fever. The rash is not associated with pain, itching, or burning. It has expanded over the last two days. He went on a camping trip in Vermont two weeks ago, and recalls a tick bite at that time. There is a single lesion on his trunk, which is erythematous with central clearing. The rest of the examination is unremarkable. What is the most appropriate next step in the management of this patient?

14. A 55-year-old Asian man with mitral stenosis secondary to rheumatic heart disease undergoes dental surgery for caries. Postoperatively, he does well and is discharged home. Two weeks later, he presents with fever, chills, fatigue, and feels "sick." Four out of four blood culture bottles are positive for gram-positive cocci. An echocardiogram is performed and shows mitral valve vegetations. Which of the following is the most likely causative organism of this patient's condition?

15. A 16-year-old Asian boy presents with a two-day history of fever, malaise, and painful enlargement of his parotid glands. He has no significant past medical history. He was born in India, and has not received any childhood vaccinations. He recently returned from a one-week vacation in India. His vital signs are stable, except for a mild fever. Examination shows bilateral parotid enlargement. The rest of the examination is unremarkable. Which of the following organs is most likely to be affected by this patient's illness?

16. A 29-year-old man returns home to Colorado after a diving trip to Honduras in Central America. He was gone for 6 days. The day he returns, he starts to develop diarrhea, abdominal cramping, and nausea. There is no mucus and blood in the stool. He has no other medical problems and does not take medications. He does not use tobacco, alcohol or drugs. His temperature is 37.2 C (98.9 F), blood pressure is 120/74 mm Hg, pulse is 80/min, and respirations are 15/min. There is no lymphadenopathy. Chest is clear to auscultation. Abdomen is soft and non-tender. There is no organomegaly. Bowel sounds are increased. Stool is negative for leukocytes and fecal occult blood. Which of the following is the most likely pathogen responsible for his symptoms?

17. A 54-year-old patient walks into a blood donation camp at a community hospital. His blood report shows an ELISA positive for HIV and HBsAg. He is notified of this finding, and a subsequent western blot test is also positive for HIV. Considering this new diagnosis of HIV, which of the following is indicated in this patient?

18. A 7-year-old Caucasian boy with a history of cystic fibrosis presents to the emergency department with a two-day history of high-grade fever and cough productive of purulent, green-colored sputum. He also complains of chest pain, which is worsened by breathing. His temperature is 39.6C (103.2F), pulse is 112/min, respirations are 26/min, and blood pressure is 90/60 mm Hg. Chest examination shows dullness on percussion and increased tactile fremitus in the right lung base. Chest x-ray shows a right lower lobe infiltrate. Which of the following is the most appropriate pharmacotherapy for this patient?

19. A 35-year-old HIV-positive male comes to the physician's office because of pain on swallowing and substernal burning for the last 3 days. Examination of the oral cavity is unremarkable. Lungs are clear to auscultation and percussion. His current medications include zidovudine, didanosine, indinavir, trimethoprim-sulfamethoxazole, and azithromycin. His last CD4 count is 40cells/microl. What is the most appropriate next step in the management of this patient?

21. A 31-year-old, HIV-infected man from New York presents to the ER with anorexia, malaise, night sweats, fever, and weight loss of 6.8kg (151b) over the past one month. He also has a cough  productive of yellow sputum. He was diagnosed with HIV two years ago. When last checked two months ago, his CD4 count was 220/microL. He is not taking any medications. His temperature is 39.2C (102.2F), pulse is 96/min, and blood pressure is 120/80 mm Hg. Physical examination reveals rales in his right upper chest. Laboratory studies show: Hematocrit 30% WBC count 3,400/microL Neutrophils 86% Bands 2% Lymphocytes 4% Monocytes 8% PPD test shows 3 mm induration. Chest x-ray reveals a right upper lobe cavitation. Sputum examination shows partially acid-fast, filamentous, branching rods. Based on these findings, which of the following organism is the most likely cause of this patient's pulmonary disease?

22. A 36-year-old man from Ohio presents with fever, malaise, fatigue, and skin lesions on his right forearm. His fever is low-grade, without any rigors or chills. His temperature is 38.4C (101 F), pulse is 87/min, and blood pressure is 124/74mm Hg. Examination shows 1-2cm warty, heaped-up skin lesions with a violaceous hue and sharply demarcated border. Some of these lesions are crusted. Wet preparation of purulent material from skin lesions shows yeast Based on these findings, what is the most likely diagnosis?

23. A 45-year-old man comes to the office and complains of intermittent, bloody diarrhea and abdominal pain for the past month. During this time period, he has lost six pounds. He was diagnosed with HIV infection in the past, but has refused antiretroviral therapy. Laboratory results show a CD4 count of 50cells/μL. The stool examination is negative. Colonoscopy with biopsy shows multiple colonic ulcerations and mucosal erosions. The biopsy shows large cells containing eosinophilic intranuclear and basophilic intracytoplasmic inclusions. What is the most likely cause of this patient's diarrhea?

24. A 22-year-old man comes to the urgent care clinic with a one-week history of fever, sore throat, and malaise. He has tried several over-the-counter products with partial relief. His temperature is 38.8C (102F), pulse is 110/min, respirations are 18/min, and blood pressure is 130/70 mm Hg. Oropharyngeal examination reveals palatal petechiae with streaky hemorrhages and blotchy, red macules. The tonsils are enlarged and covered with whitish exudate. Mild jaundice is present. Enlarged lymph nodes are palpable posterior to the sternocleidomastoid muscle bilaterally. Axillary lymphadenopathy is also present. Abdominal examination reveals normal bowel sounds and mild hepatosplenomegaly. His complete blood count is shown below: Hemoglobin 14.0 g/L MCV 88fl Platelets 140,000/mm3 Leukocyte count 14,500/mm3 Neutrophils 33% Lymphocytes 66% Eosinophils 1% Which of the following is commonly associated with this patient's condition?

25. A 25-year-old HIV-positive male comes to a physician with complaints of headache and left-sided weakness of recent onset. His temperature is 38C (100.8F), blood pressure is 115/70mm Hg, respirations are 14/min, and pulse is 73/min. Neurological examination reveals decreased power, hyperreflexia, and upgoing plantars in the left upper and lower limb. Neuroimaging by CT shows multiple ring-enhancing lesions. What is the most appropriate next step in management?

26. A 43-year-old male presents to a physician with an ulcer on the shaft of his penis. The ulcer is non- tender, with a raised border and a smooth base. There is bilateral inguinal adenopathy. The rest of the examination is unremarkable. Dark field microscopy of a specimen from the ulcer base reveals spirochetes. Which of the following additional screening studies should be performed on this patient?

27. A 25-year-old female presents to her physician with a painful ulcerative lesion on her labia for the past 2 days. She also complains of dysuria. She admits to having sexual intercourse with multiple partners for the last 6 years. Tzanck preparations of one of her lesions reveal multi-nucleated giant cells. She is encouraged to undergo testing for HIV and other STDs. Which of the following is the most appropriate screening test for HIV infection?

28. A 73-year-old diabetic man presents with low-grade fever, facial pain over his right maxilla, and bloody nasal discharge for the last three days. For the last day, he has had diplopia. He was diagnosed with diabetes mellitus 10 years ago. For the last year, he has been on insulin. His most recent hemoglobinA1C was 12.0. His temperature is 39.0C (102.2F), pulse is 88/min, and blood pressure is 130/76mm Hg. Examination shows right-sided nasal congestion and necrosis of the right nasal turbinate with tenderness over the right maxillary sinus. There is chemosis and proptosis of his right eye. CT scan shows opacification of the right maxillary sinus. Which of the following is the most likely causative organism?

29. An 18-year-old young man comes to your clinic with complaints of fatigue, malaise, fever, and sore throat for the past few days. His temperature is 38.8C (101 F), pulse is 90/min, respirations are 18/min, and blood pressure is 135/70 mm Hg. Physical examination reveals cervical lymphadenopathy, pharyngeal hyperemia, and splenomegaly. Complete blood count shows leukocytosis with predominant atypical lymphocytes. The heterophile antibody test is positive. When you ask if he has any questions, he replies with, "Well, I'm a rugby player in school, so I need to know when I can start playing again." What is the most appropriate advice for this patient?

30. A 25-year-old man presents to the physician's office because of a clenched fist injury ("fight bite") incurred during a gang fight. The injury occurred two days ago and he has now started to develop pain, swelling, and redness around the wound. His immunizations are up to date. His wounds are cleaned in the clinic. Plain films of hand do not show evidence of foreign body or osteomyelitis. Which of the following is the most appropriate antibiotic for his current condition?

31. A 30-year-old white, HIV-infected male from Ohio presents with low-grade fever, anorexia and weight loss of 3.6kg (Bib) for the past 3 weeks. His baseline PPD test was negative. His pulse is 87/min, blood pressure is 126/76 mm Hg, temperature is 38.3C (101F), and respirations are 18/min. Examination shows oropharyngeal ulcers and hepatosplenomegaly. Lab testing shows: Hematocrit 36% Platelet count 50,000/microL WBC count 3, 1 00/microL Blood culture establishes the diagnosis of histoplasmosis. What is the most appropriate next step in the management of this patient?

32. A 67-year-old man presents to his primary care provider in January with fever and a productive cough. The patient had been seen ten days earlier with complaints of fever to 102F (39.0C), myalgias, rhinorrhea, and dry cough. At that time, his lung exam revealed occasional crackles. He was given a medication and told to follow up if his symptoms worsened. The symptoms did remit over the first five days, but he began to feel worse again two days ago. He smokes a half-pack of cigarettes per day and drinks alcohol several times a week. On exam today, his temperature is 102.3F (39.3C), and lung exam reveals increased tactile fremitus in the left lower lobe. What is the most likely pathogen responsible for his current condition?

33. A 54-year-old diabetic woman comes to the emergency department because of increasing neck and facial pain, fever, and chills. A few weeks ago, she developed an infection on the side of her neck. She thought it would go away with over-the-counter medication, but the infection has now started to drain. For the past twenty years, she has had diabetes, which is well-controlled with an oral hypoglycemic. She denies trauma, travel, and smoking. Physical examination reveals an area of erythema and induration at the base of the neck. Serosanguineous fluid is draining from a small defect in the skin near the center of the lesion. There is no crepitus. Histological analysis of the discharge reveals the presence of gram-positive, branching bacteria. The treatment for this patient is·

34. A 28-year-old man presents to ER with fever, chills, and generalized weakness for the past one week. He has no history of pre-existing heart disease, but he was admitted to the hospital six months ago for cellulitis of the right arm. His temperature is 40.0C (104 F), pulse is 110/min, respirations are 22/min, and blood pressure is 110/65 mmHg. Oropharynx is clear. Lungs are clear to auscultation. A holosystolic murmur is heard at the lower sternum which increases in intensity with inspiration. His blood is drawn and sent for culture. What is the most appropriate initial antibiotic therapy for this patient?

35. A 43-year-old HIV-positive male presents to your office with several exophytic purple skin masses on his lower abdomen. Physical examination reveals tender hepatomegaly and an abdominal CT scan shows nodular, contrast-enhanced intrahepatic lesions of variable size. Liver biopsy is attempted but severe hemorrhage results. Which of the following is the most likely cause of this patient's condition?

37. A 7-year-old boy is brought to the office by his mother due to anal pruritus for the past month. His symptoms are most severe at night. Physical examination is normal, except for mild perianal erythema. Stool examination is normal. "Scotch tape test" is positive. Which of the following is the most appropriate treatment for this child's condition?

38. A 45-year-old female presents to emergency room complaining of urinary frequency, burning during urination, and weakness. Her last menstrual period was one year ago, and she is not sexually active.  She is not taking any medications. Her temperature is 37.8 C (100 F), blood pressure is 120/76 mmHg, pulse is 80/min, and respirations are 14/min. Very mild costovertebral angle tenderness is present. IV ceftriaxone is started. Two days later, the patient feels much better. Antibiotic susceptibility testing returned with an uropathogen (E. coli) highly sensitive to ceftriaxone, gentamicin, ciprofloxacin and trimethoprim/sulfamethoxazole (TMP/SMX). Which of the following is the most reasonable next step in the management of this patient?

39. A 19-year-old man presents to your office with a one-week history of fever, fatigue, and sore throat. He denies diarrhea or rash. He has no significant past medical history. His brother died of cystic fibrosis at 14 years of age. He admits to occasional cigarette use and alcohol consumption. He has smoked marijuana several times but has never used injectable drugs. He is sexually active with one partner and uses condoms occasionally. Physical examination reveals enlarged tonsils with a whitish exudate and enlarged, slightly tender lymph nodes deep to the sternocleidomastoid muscle bilaterally. The exam is otherwise unremarkable. Which of the following is the best initial test in this patient?

40. A 24-year-old man from Long Island, New York, presents with fever, drenching sweats, and malaise for the past week. For the last few days, he has noted jaundice and dark-colored urine. He recalls being bitten by a tick two weeks ago. His surgical history includes splenectomy after a car accident 10 years ago. He does not use tobacco, alcohol, or illicit drugs. His temperature is 39.5C (103F), pulse is 106/min, and blood pressure is 110/70 mm Hg. Systemic examination is unremarkable, except for jaundice. Based on these findings, what is the most likely diagnosis?

41. A 37-year-old man comes to his primary care physician for the evaluation of slightly pruritic skin lesions around his anus. He denies fever, malaise, and anorexia. He is sexually active with multiple male partners and occasionally uses condoms. He has never been tested for HIV or other sexually transmitted diseases. He has no drug allergies. Examination shows skin-colored, verrucous, papilliform lesions around his anus. Which of the following is the most appropriate treatment for this patient?

42. 28-year-old, HIV-infected female from Michigan is admitted with Pneumocystis jirovecii pneumonia (PCP) secondary to noncompliance with prophylaxis. She was diagnosed with HIV infection three years ago. Her C04 count on admission is 30/microl, and viral load is 300,000copies/ml. Her pneumonia is adequately treated with IV antibiotics, and she subsequently receives zidovudine, lamivudine, nelfinavir, and trimethoprim-sulfamethoxazole. What is the most appropriate drug to be added to her current regimen?

43. A 27-year-old, HIV-positive man comes to his physician with a two-day history of fever, profuse watery diarrhea, and abdominal cramps. He has been taking zidovudine, didanosine, and indinavir for the past eight months. His temperature is 37.9C (100.2F), pulse is 102/min, respirations are 14/min, and blood pressure is 105/70 mm Hg. He is started on fluid and electrolyte support. What is the most appropriate next step in the management of this patient?

44. A 65-year-old Connecticut resident calls your office after finding a 3 mm red-brown tick attached to his right leg. He just returned from a hiking trip and was about to a take a shower when he discovered the tick. Which of the following is the best advice to give this patient?

45. A 75-year-old female nursing home resident complains of cough and fever. Her past medical history is significant for hypertension, myocardial infarction (experienced two years ago), and a traumatic right foot amputation. Her current medications are atenolol, hydrochlorothiazide, and aspirin. Her temperature is 39.4 C (103 F), pulse is 110/min, respirations are 22/min, and blood pressure is 110/76 mmHg. Crackles are present at right lung base. Chest x-ray reveals a right lower lobe infiltrate. Which of the following pathogens is the most likely cause of this patient's condition?

46. A 45-year-old man presents to the emergency room with a two-day history of fever, dyspnea, abdominal pain, and diarrhea. He has no chest pain, but complains of dry cough. His past medical history is significant for bone marrow transplantation for acute myeloid leukemia (AML) three months ago. His temperature is 39.C (102.2F), blood pressure is 122/80 mm Hg, pulse is 98/min, and respirations are 22/min. Exam of the oropharynx reveals thrush. Lungs exam demonstrates bilateral diffuse rales. Heart sounds are regular. Nonspecific abdominal tenderness is present. The chest radiograph shows multifocal, diffuse patchy infiltrates. Which of the following is the most likely cause of this patient's current condition?

47. A 55-year-old woman presents with a three-week history of low-grade fever, weight loss of 4.5kg (10lb), and malaise. She is known to have mitral valve prolapse, but is otherwise healthy. She underwent a tooth extraction one month ago. She denies alcohol, tobacco, and illicit drug use. Her temperature is 38.5C (101.3F), pulse is 90/min, respirations are 18/min, and blood pressure is 145/76 mm Hg. Her chest is clear to auscultation and percussion. Cardiac examination reveals a III/IV holosystolic murmur at the apex that radiates to the axilla. Chest x-ray is normal. Urinalysis is unremarkable. Blood cultures are drawn and empiric antibiotics are started. Echocardiogram shows mitral regurgitation with vegetation on the mitral valve. Which of the following organisms is the most likely cause of this patient's condition?

48. A 55-year-old pig farmer is brought to the emergency department (ED) after having a seizure two hours ago. During his transit to the ED, he has another seizure. On arrival, he is unconscious, pulseless, and not breathing. Resuscitation is successful and the patient is stabilized; however, he does not do well over the next several days and is eventually declared dead. His wife says that he had been healthy most of his life, except for the past few weeks, when he was complaining of headaches. Autopsy shows multiple fluid-filled cysts in the brain parenchyma. Which of the following is the most likely diagnosis of this patient?

50. A 50-year-old man presents to the office with fatigue, malaise, and disabling joint pain in his fingers, wrists, shoulder, hips, knees, and ankles. His pain is severe and associated with a mild degree of morning stiffness for 10-15 minutes. He occasionally takes acetaminophen and ibuprofen for this pain. He has a 10-pack-year smoking history. He does not drink alcohol. Family history includes an uncle who died of liver cancer. On examination, there is grayish skin pigmentation, most prominent on the exposed parts. Abdominal examination is significant for liver enlargement 2 cm below the costal margin. Laboratory studies reveal the following: Hemoglobin 13.0 g/L Leukocyte count 5,500/mm3 Serum creatinine 0.8 mg/dl Blood glucose 218mg/dl Aspartate aminotransferase (SGOT) 128 U/L Alanine aminotransferase (SGPT) 155 U/L Alkaline phosphatase 120 U/L Serum iron 450 mol/L (50-170g/dL) Transferrin saturation of iron 62% (22-47%) Serum Ferritin 3000ng/L (15-200 ng/ml, males) X-ray of the joints shows narrowing of joint spaces and diffuses demineralization. This patient's condition makes him more vulnerable to which of the following infections?

51. A 19-year-old white male presents with nausea, vomiting, and abdominal cramps. He has had four episodes of vomiting over the last two hours. He has not had diarrhea or fever. Four hours ago, he ate a salad from a local restaurant. His pulse is 82/min, blood pressure is 120/80 mm Hg, and temperature is 37.2C (99F). Abdominal and rectal examinations are unremarkable. Which of the following is the most likely cause of this patient's symptoms?

52. A 34-year-old recently migrated African American male presents with severe headache and high- grade fever with chills for the last two days. He also complains of severe malaise, myalgia and vomiting. He adds that the present episode started with feeling of intense cold and chills with shivering followed by high-grade fever. He had two similar episodes in the past, when he was in Africa. His vitals are, T 38.9C (102F), RR 20/min, PR 110/min and BP100/60 mm Hg. He has pallor with mild splenomegaly but rest of his physical examination is normal. What is the most likely diagnosis in this patient?

53. A 22-year-old man comes to the urgent care clinic with a one-week history of fever, sore throat, and malaise. He has tried several over-the-counter products with partial relief. His temperature is 38.8C (102F), pulse is 110/min, respirations are 18/min, and blood pressure is 130/70 mm Hg. Oropharyngeal examination reveals palatal petechiae with streaky hemorrhages and blotchy, red macules. The tonsils are enlarged and covered with whitish exudate. Mild jaundice is present. Enlarged lymph nodes are palpable posterior to the sternocleidomastoid muscle bilaterally. Axillary lymphadenopathy is also present. Abdominal examination reveals normal bowel sounds and mild hepatosplenomegaly. His complete blood count is shown below: Hemoglobin 14.0 g/L MCV 88 f l Platelets 140,000/mm3 Leukocyte count 14,500/mm3 Neutrophils 33% Lymphocytes 66% Eosinophils 1% Which of the following is commonly associated with this patient's condition?

56. A 36-year-old man from Ohio presents with fever, malaise, fatigue, and skin lesions on his right forearm. His fever is low-grade, without any rigors or chills. His temperature is 38.4C (101 F), pulse is 87/min, and blood pressure is 124/74mm Hg. Examination shows 1-2cm warty, heaped-up skin lesions with a violaceous hue and sharply demarcated border. Some of these lesions are crusted. Wet  preparation of purulent material from skin lesions shows yeast Based on these findings, what is the most likely diagnosis?

57. A 72-year-old male presents with a two-day history of intense pain in his right ear, along with ear discharge. The pain is so severe that he is unable to sleep. It radiates to his temporomandibular joint and is aggravated by chewing. His disease has worsened despite the use of topical antibiotics. He takes metformin and enalapril. On physical examination, granulation tissue is noted in the lower part of his external auditory canal. Cranial nerves are intact. Oropharynx is clear without exudate. Which of the following is the most likely causative organism of this patient's ear condition?

58. A 65-year-old African-American man is hospitalized after a car accident. He has a vertebral fracture at the level of the fifth thoracic vertebra and is unable to move his lower extremities. Since his injury, he has needed a catheter for micturition. Which of the following is the most effective measure for decreasing the risk of a urinary tract infection in patients requiring bladder catheterization?

59. A 34-year-old male comes to the physician's office due to a severely pruritic lesions on his hands. He denies any trauma but recalls using his hands to change the sand of his children's sandbox when they went to Miami Beach three days ago. He later developed pruritic, erythematous papules over his arm. These papules progressed to serpiginous, reddish brown, elevated lesions, which are evident bilaterally on the upper extremities on exam. What is the most likely diagnosis?

60. A 54-year-old diabetic woman comes to the emergency department because of increasing neck and facial pain, fever, and chills. A few weeks ago, she developed an infection on the side of her neck. She thought it would go away with over-the-counter medication, but the infection has now started to drain. For the past twenty years, she has had diabetes, which is well-controlled with an oral hypoglycemic. She denies trauma, travel, and smoking. Physical examination reveals an area of erythema and induration at the base of the neck. Serosanguineous fluid is draining from a small defect in the skin near the center of the lesion. There is no crepitus. Histological analysis of the discharge reveals the presence of gram positive, branching bacteria. The treatment for this patient is·

61. A 72-year-old man presents to the ED during the month of January complaining of non-productive cough, fever, malaise, runny nose, and severe body aches. The symptoms came on suddenly last night. He has no other medical problems. Physical examination reveals a temperature of 38.9°C (102.0.F) and oxygen saturation of 88% on room air. His lung exam reveals diffuse crackles with occasional wheezes. Laboratory values are: Hematocrit 44% Platelets 219,000/mm3 Leukocyte count 4,100/mm3 Neutrophils 65% Lymphocytes 32% His chest x-ray reveals diffuse interstitial infiltrates bilaterally. What is the most appropriate initial therapy for this patient?

62. A 49-year-old man presents with a three-week history of fever, weight loss, and anorexia. He also reports muscle aches. He has no cough or shortness of breath. He has a thirty pack-year history of cigarette smoking. His temperature is 38.9C (102 F), blood pressure is 120/76mm Hg, pulse is 90/min, and respirations are 16/min. Lungs are clear to auscultation. The rest of the physical examination is unremarkable. Blood cultures reveal Streptococcus bovis. Echocardiogram reveals vegetations on the mitral valve. Other than antibiotic treatment, what further step is recommended in this patient?

63. A 32-year-old man from Arkansas presents to physician with a two-day history of fever, headache, malaise, and myalgias. His family says that he seems slightly confused. He recalls having a tick bite two weeks ago after walking through the woods. His temperature is 39C (102F), pulse is 90/min, and blood pressure is 125/80 mm Hg. Neck is supple and there is no lymphadenopathy noted. Oropharynx is clear. Chest auscultation is unremarkable. Abdomen is soft and non-tender. There is no rash evident. Neurologic examination is nonfocal. Laboratory testing shows: Complete blood count: Hemoglobin 14.0 g/L MCV 88 fL Platelets 78,000/mm3 Leukocyte count 2,500/mm3 Neutrophils 56% Eosinophils 1%,Lymphocytes 33% Monocytes 10% Liver studies: Total protein, serum 6.5 g/dL Total bilirubin 1.0 mg/dL Direct bilirubin 0.8 mg/dL Alkaline phosphatase 110 U/L Aspartate aminotransferase (SGOT) 98 U/L Alanine aminotransferase (SGPT) 105 U/L What is the most appropriate next step in the management of this patient?

64. A 26-year-old male presents to your office with periodic flank pain. He also noticed that his urine was red during the last several days. He is known to be HIV-positive. One month ago, he presented with thrush. At that time, he was found to have a CD4 count of 100, and was started on anti-retroviral therapy. His current CD4 count is 250. Physical examination reveals no oral cavity lesions. The lungs are clear on auscultation. The serum creatinine level is 2.2 mg/dl. Urinalysis shows hematuria and needle-shaped crystals in the sediment. Which of the following is the most likely cause of this patient's current condition?

65. A 23-year-old man is brought to the emergency room because of confusion and hallucinations. While in ER, he has an episode of generalized tonic-clonic seizures. His past medical history is significant for illicit drug use. His temperature is 40.0C (104.0F), pulse is 95/min, and blood pressure is 120/80 mm Hg. He is confused and disoriented. Fundoscopy is with in normal limits. There is no neck stiffness. The neurological examination shows upgoing plantar reflexes bilaterally. Lumbar puncture is performed and CSF analysis shows the following: Glucose 35mg/dl Protein 80mg/dl WBC count 150/cm3 Neutrophils 10% Lymphocytes 90% Gram stain Negative CT scan of the brain without contrast is normal. Which of the following is the most appropriate next step in the management of this patient?

66. A 22-year-old woman presents to the emergency department after she is bitten on her right arm by her neighbor's dog. She provoked the dog while it was eating. The dog is not immunized against rabies, but does not show any signs of rabies. Her right forearm shows a deep bite wound. Her last tetanus booster was 3 years ago. Her wound is cleaned with soap, water, and povidone-iodine solution. What is the most appropriate next step in the management of this patient?

67. A 12-year-old boy is brought to the emergency department because of severe pain near his left knee. He has sickle cell disease, and has been hospitalized previously for sickle cell crisis. Vital signs are notable for mild fever. Examination of the left lower extremity reveals a normal knee joint with marked tenderness and swelling over the proximal tibia. Labs show leukocytosis and elevated ESR. He is subsequently diagnosed with osteomyelitis. Which of the following organisms is the most likely cause of his condition?

68. A 25-year-old male comes to the clinic because of a painless ulcer on his penis. He denies fever or urethral discharge, but admits to recent sexual activity with a prostitute. He describes severe rash and face swelling with penicillin. Physical examination reveals a shallow, non-tender ulcer. There is no lymphadenopathy. Dark field microscopy reveals spirochetes. Which of the following is the most appropriate treatment for this patient?

69. A 67-year-old man presents to his primary care provider in January with fever and a productive cough. The patient had been seen ten days earlier with complaints of fever to 102F (39.0C), myalgias, rhinorrhea, and dry cough. At that time, his lung exam revealed occasional crackles. He was given a medication and told to follow up if his symptoms worsened. The symptoms did remit over the first five days, but he began to feel worse again two days ago. He smokes a half-pack of cigarettes per day and drinks alcohol several times a week. On exam today, his temperature is 102.3F (39.3C), and lung exam reveals increased tactile fremitus in the left lower lobe. What is the most likely pathogen responsible for his current condition?

70. 65-year-old female who lives in nursing home and is bed ridden due to severe right hemiparesis is brought to the ER because of altered mental status and decreased oral intake. Her past medical history includes hypertension, diabetes, hyperlipidemia, and myocardial infarction. She has a chronic indwelling Foley catheter to avoid contamination of a sacral decubitus ulcer. She is febrile in the ER. Examination shows dry mucus membranes and clear lungs. She is disoriented. The decubitus ulcer has good granulation tissue and does not appear infected. Labs show: Hemoglobin 12.0 g/L Leukocyte count 12 500/mm3 Blood urea nitrogen (BUN) 28 mg/dL Serum creatinine 0.8 mg/dL Serum bicarbonate 24 mg/dL Urinalysis: Specific gravity 1.036 Protein 1+ pH 8.5 Blood negative Glucose 1+ Ketones negative Leukocyte esterase positive WBC 50-100/hpf Bacteria few Which of the following is the most likely cause of her altered mental status?

71. A 64-year-old male recovering from an upper respiratory infection develops malaise and productive cough. Two days later he presents to the emergency department with confusion and severe dyspnea. He reports coughing up copious amounts of yellowish sputum streaked with blood today. On physical examination, his temperature is 40C (104F), blood pressure is 150/90 mm Hg, pulse is 110/min, and respirations are 24/min. Chest x-ray reveals infiltrates in the lung midfields bilaterally as well as multiple thinwalled cavities. What is the most likely cause of this patient's condition?

72. A 33-year-old man presents with low-grade fever, abdominal cramps, and diarrhea for the past six hours. He has had eight episodes of loose, watery stool containing blood and mucus over this time period. Last night, he ate shrimp and crab meat at a local restaurant. His current pulse is 85/min, blood pressure is 110/80 mm Hg, and temperature is 37.7C (99.9F). There are no significant findings on abdominal or rectal examinations. Stool examination shows numerous red blood cells and leukocytes. Which of the following is the most likely causative organism of this patient's condition?

73. A 35-year-old man presents to the office with a two-week history of low-grade fever and progressive weakness. He has "a heart murmur detected a long time ago." He denies illicit drug use. Physical examination reveals splinter hemorrhages, small petechiae on the palatal mucosa, and an audible murmur. His ESR is 60/min. Urinalysis reveals microscopic hematuria and 1+proteinuria. Which of the following valvular dysfunctions is most likely to be detected?

75. A 46-year-old farmer comes to the physician because of pain and swelling of his right heel. He accidentally stepped on a rusty nail while working 2 weeks ago. Although he applied over the-counter antibiotic cream locally and took acetaminophen orally, he continued to have pain at the site of the injury. He has no other medical problems and takes no medication. He has no known drug allergies. He smokes 2-3 cigarettes a day and drinks alcohol occasionally. His temperature is 38.3 C (101 F), blood pressure is 140/90 mm Hg, pulse is 84/min and respirations are 14/min. On examination, the right heel is swollen, red, and warm and tender to touch. A small puncture wound is visible. Laboratory reports show mild leukocytosis. X-ray of the right foot shows features suggestive of osteomyelitis. The most likely cause of the patient's symptoms is infection with which of the following?

76. A 36-year-old woman who lives in the suburbs of a large city comes to your office for a tuberculin skin test. She will be volunteering in her daughter's school cafeteria and the school district requires tuberculin testing. You inject a small amount of Mycobacterium tuberculosis purified protein derivative (PPD) in the skin and 2 days later she returns for a reading. You measure 12 mm of induration. She reports no history of tuberculosis exposure and no underlying medical conditions. She has never before been tested for tuberculosis. She was born in the United States, is not a healthcare worker, and has never spent time in prison. What is the best next step in her management?

77. A 43-year-old male presents to a physician with an ulcer on the shaft of his penis. The ulcer is non- tender, with a raised border and a smooth base. There is bilateral inguinal adenopathy. The rest of the examination is unremarkable. Dark field microscopy of a specimen from the ulcer base reveals spirochetes. Which of the following additional screening studies should be performed on this patient?

78. A 19-year-old man presents to your office with a one-week history of fever, fatigue, and sore throat. He denies diarrhea or rash. He has no significant past medical history. His brother died of cystic fibrosis at 14 years of age. He admits to occasional cigarette use and alcohol consumption. He has smoked marijuana several times but has never used injectable drugs. He is sexually active with one partner and uses condoms occasionally. Physical examination reveals enlarged tonsils with a whitish exudate and enlarged, slightly tender lymph nodes deep to the sternocleidomastoid muscle bilaterally. The exam is otherwise unremarkable. Which of the following is the best initial test in this patient?

79. A 22-year-old female presents with a two-day history of inability to close her right eye, a low-grade fever, and a rash on her trunk. There is no burning or itching associated with the rash. She denies headache, confusion, neck stiffness, numbness, and tingling. She went on a camping trip in Vermont four weeks ago but cannot recall any exposure to ticks. She was treated for chlamydia! Urethritis infection in the past. She has been using over-the-counter acetaminophen for fever; she noticed the rash after beginning the acetaminophen. Physical examination reveals several erythematous lesions around her waistline. Neurological examination shows right-sided facial nerve palsy. Based on these findings, what is the most likely diagnosis?

80. A 31-year-old, HIV-infected man from New York presents to the ER with anorexia, malaise, night sweats, fever, and weight loss of 6.8kg (15 1b) over the past one month. He also has a cough productive of yellow sputum. He was diagnosed with HIV two years ago. When last checked two months ago, his CD4 count was 220/microL. He is not taking any medications. His temperature is 39.2C (102.2F), pulse is 96/min, and blood pressure is 120/80mm Hg. Physical examination reveals rales in his right upper chest. Laboratory studies show: Hematocrit 30% WBC count 3,400/microL Neutrophils 86% Bands 2% Lymphocytes 4% Monocytes 8% PPD test shows 3 mm induration. Chest x-ray reveals a right upper lobe cavitation. Sputum examination shows partially acid- fast, filamentous, branching rods. Based on these findings, which of the following organism is the most likely cause of this patient's pulmonary disease?

82. A 22-year-old male student presents with an acute onset of fever, double vision, and painful swelling around his eyes. He also has significant muscle pain in his neck and jaw muscles. A week earlier, he experienced a period of abdominal pain, nausea, vomiting, and diarrhea, all of which resolved spontaneously. He has a history of intravenous drug abuse but has recently completed of a drug rehabilitation program. He is febrile. Physical examination shows "splinter" hemorrhages, periorbital edema, and chemosis. Chest is clear to auscultation. Cardiac exam reveals no murmur. Abdomen is soft and nontender with no organomegaly. His complete blood count is shown below: Hemoglobin 13.0 g/L MCV 85 fl Platelets 228,000/mm3 Leukocyte count 10,500/mm3 Neutrophils 56% Eosinophils 21% Lymphocytes 23% Based on these findings, what is the most likely diagnosis?

83. A 19-year-old woman comes to the physician because of fever, joint pain, and rash. The rash started on her face and is spreading down her body. She has pain in her fingers, wrists, and knees. She denies any neck stiffness, nausea, or vomiting. She has been sexually active with multiple partners. Her vaccination status is unknown. Her pulse is 86/min, blood pressure is 125/75 mm Hg, and temperature is 37.7C (99.8F). Physical examination reveals a maculopapular rash on her face and chest. Posterior auricular, cervical, and suboccipital lymphadenopathy is present. She has mild conjunctivitis. Oropharynx is clear. Chest is clearto auscultation. What is the most likely diagnosis?

84. 5-year-old Hispanic girl is brought to the emergency department (ED) due to a cat bite on her right upper extremity. She was bitten after rambunctiously playing for several minutes with the cat, which had just been given to her as a birthday gift. Her most recent booster tetanus vaccine was one year ago. Her temperature is 36.7C (98F), blood pressure is 108/70 mm Hg, pulse is 107/min, and respirations are 21/min. Physical examination reveals a deep puncture wound on the volar aspect of her right forearm. Before going to the ED, her mother cleaned the wound with hydrogen peroxide. There is no visible debris in the wound, and little bleeding is evident. Neurovascular function is intact. Her wound is cleaned in the ED with Betadine and lavaged with saline solution. What is the best next step in managing this girl's care?

85. A 57-year-old male comes to your office in the middle of January. He complains of a 4-day history of a nonproductive cough and coryza. He also has vague muscle aches and a mild headache. He denies any shortness of breath or chest pain. His past medical history is significant for hyperlipidemia and impaired glucose tolerance. He takes aspirin and simvastatin 40 mg at bedtime. He has no known drug allergies. His medical records show that he did not show up for his scheduled annual influenza vaccine this year. His temperature is 38.5 C (101.3 F), blood pressure is 135/80 mm Hg, and pulse is 88/min. Physical examination shows conjunctival redness and an erythematous oropharynx. The tympanic membranes are clear. The heart sounds are audible with no added murmurs, rubs or gallops. His breath sounds are vesicular in quality and equal bilaterally. Which of the following is the most appropriate next step in management?

86. A 60-year-old Caucasian woman undergoes elective coronary artery bypass surgery and aortic valve replacement. Her postoperative course is complicated by acute renal failure, atrial fibrillation, and pulmonary edema. On the third postoperative day, extubation is attempted but not tolerated, thus warranting reintubation. On the fifth postoperative day, she develops a fever to 38.9 C (102 F). Her pulse is 110-120/min and irregular, respirations are 36/min, and blood pressure is 110/65 mmHg. Her chest x-ray shows right middle and lower lobe infiltrates. WBC count is elevated with bandemia. Gram stain of her sputum shows gram-negative rods. She is given intravenous ceftriaxone; however, she deteriorates over the next 24 hours. Which of the following is the most appropriate next step in the management of this patient?

87. A 26-year-old man comes to his physician with a two-week history of fatigue, fever, muscle aches, and arthralgias. He denies any weight loss. His temperature is 37.7C (99.9F), blood pressure is 115/75 mm Hg, respirations are 14/min, and pulse is 75/min. Physical examination is unremarkable, except for splenomegaly. Laboratory studies show: Hemoglobin 13 gm/dL WBC count 12,000/microL Neutrophils 22% Lymphocytes 70% Monocytes 5% Basophils 1% Eosinophils 2% Platelet count 220,000/microL Peripheral blood smear shows large basophilic lymphocytes with a vacuolated appearance. Heterophile antibody test is negative. What is the most likely cause of this patient's symptoms?

88. A 27-year-old man presents with symptoms of fever, chills, malaise, and joint discomfort in his hands and knees. He looks unwell, his temperature is 39.4°C, blood pressure 115/70 mm Hg, pulse 110/min, head and neck is normal, and his jugular venous pressure (JVP) has a prominent c-v wave. There is also a 3/6 pan-systolic murmur heard at the right sternal border that increases with respiration. His lungs are clear, abdomen is soft, and hand joints are normal. He has multiple puncture sites on his forearms from injection drug use. Which of the following is the most likely causative organism?

89. A 17-year-old man presents with new symptoms of fatigue, malaise, fever, and a sore throat. He has no significant past medical history and is not on any medications. Physical examination is entirely normal except for enlarged, palpable cervical, lymph nodes. He reports no weight loss or night sweats. Laboratory investigations include a normal chest x-ray, negative throat swab, but abnormal blood film with atypical lymphocytes. The hemoglobin is 15.5 g/dL; hematocrit 42%; platelets 290,000/mL; WBC 10500/mL, with 45% segmented neutrophils, 1% eosinophils, and 54% lymphocytes, of which 36% were atypical. Which of the following is the most appropriate initial diagnostic test?

90. A 34-year-old man is traveling in Southeast Asia on business. He is staying in Western-style hotels and eating food in large restaurants. He has not eaten from street vendors. One week after arrival, he develops symptoms of anorexia, nausea, and abdominal cramps followed by the sudden onset of watery diarrhea. He has no fever or chills and there is no blood or pus in the stools. Which of the following is the most appropriate therapy for his condition?

91. A 30-year-old male presents with right upper quadrant pain. He has been well except for an episode of diarrhea that occurred 4 months ago, just after he returned from a missionary trip to Mexico. He has lost 7 pounds. He is not having diarrhea. His blood pressure is 140/70, pulse 80, and temperature 37.5°C (99.5°F). On physical examination there is right upper-quadrant tenderness without rebound. There is some radiation of the pain to the shoulder. The liver is percussed at 14 cm. There is no lower-quadrant tenderness. Bowel sounds are normal and active. Which of the following is the most appropriate next step in evaluation of the patient?

92. A 45-year-old woman is undergoing chemotherapy for breast cancer. She presents 10 days after her last chemotherapy with fever (temperature >38.5C), but no other symptoms except a sore throat and mouth. On examination, she looks well, there is oral mucositis, ears are normal, lungs are clear, and the central line site is clean. The CXR, urinalysis, and biochemistry are normal. Her WBC is 800/mL and the absolute neutrophil count is low (<500). Which of the following is the most appropriate next step in management?

93. An elderly bedridden patient in the hospital develops cough, fever, and shortness of breath. On examination, the JVP is 4 cm, heart sounds are normal, and there are crackles on inspiration in the right lower lobe. A CXR reveals a new right lower lobe infiltrate and his WBC is 15,000/mL. He was admitted to the hospital 7 days ago for the treatment of congestive heart failure. Which of the following is the most likely diagnosis?

94. A 74-year-old man residing in a nursing home develops symptoms of high fever, diarrhea, chest pain, and nonproductive cough. His temperature is 40C, blood pressure 120/80 mm Hg, respiration 24/min, and oxygen saturation 90%. He has bibasilar crackles, normal heart sounds, and a soft nontender abdomen. His CXR reveals bilateral lower lobe infiltrates. He is not able to provide any sputum, and the urine is positive for legionella antigen. Which of the following is the most appropriate antibiotic choice?

95. A 28-year-old female presents to her internist with a 2-day history of low-grade fever and lower abdominal pain. She denies nausea, vomiting, or diarrhea. On physical examination, there is temperature of 38.3°C (100.9°F) and bilateral lower quadrant tenderness, without point or rebound tenderness. Bowel sounds are normal. On pelvic examination, an exudate is present and there is tenderness on motion of the cervix. Her white blood cell count is 15,000/μL and urinalysis shows no red or white blood cells. Serum β-hCG is undetectable. Which of the following is the best next step in management?

96. A 35-year-old male complains of inability to close his right eye. Examination shows facial nerve weakness of the upper and lower halves of the face. There are no other cranial nerve abnormalities, and the rest of the neurological examination is normal. Examination of the heart, chest, abdomen, and skin show no additional abnormalities. There is no lymphadenopathy. About one month ago the patient was seen by a dermatologist for a bull’s-eye skin rash. The patient lives in upstate New York and returned from a camping trip a few weeks before noting the rash. Which of the following is the most likely diagnosis?

97. An 18-year-old woman presents with headache, anorexia, chilly sensations, and discomfort on both sides of her jaw. She has also noticed discomfort in both lower abdominal quadrants. Physical examination reveals bilateral enlarged parotid glands that are doughy, elastic, and slightly tender; with a reddened orifice of Stensen’s duct. Her abdomen is soft with bilateral lower quadrant abdominal tenderness; a temperature of 38.5°C; and a pulse rate of 92/min. Laboratory data show hemoglobin 13 g/dL; hematocrit 40%; white blood cells (WBC) 9000/mL, with 35% segmented neutrophils, 7% monocytes, and 58% lymphocytes. Which of the following is the most likely cause for her abdominal pain and tenderness?

98. A 73-year-old man from a nursing home develops headache, fever, cough, sore throat, malaise, and severe myalgia during a community outbreak affecting numerous other residents at the home. The symptoms gradually resolve after 3 days, and he starts feeling better but then there is a reappearance of his fever, with cough and yellow sputum production. On examination, his temperature is 38.5C, pulse 100/min, respiration 24/min, oxygen saturation 88% and crackles in the right lower lung base, bronchial breath sounds and dull- ness on percussion. CXR reveals a new infiltrate in the right lower lobe. Which of the following is the most likely causative organism?

99. A 56-year-old man is having intermittent fevers and malaise for the past 2 weeks. He has no other localizing symptoms. Two months ago, he had valve replacement surgery for a bicuspid aortic valve. A mechanical valve was inserted and his postoperative course was uncomplicated. On examination, his temperature is 38C, blood pressure 124/80 mm Hg, pulse 72/min, and head and neck are normal. There is a 3/6 systolic ejection murmur, the second heart sound is mechanical, and a 2/6 early diastolic murmur is heard. The lungs are clear and the skin examination is normal. Three sets of blood cultures are drawn and an urgent echocardiogram is ordered. Which of the following is the most likely causative organism?

100. Two students from a university dormitory building have contracted meningitis due to Neisseria meningitides. Which of the following students in the dormitory are most likely to benefit from chemoprophylaxis?

101. A 25-year-old woman is admitted with fever and hypotension. She has a 3-day history of feeling feverish. She has no history of chronic disease, but she uses tampons for heavy menses. She is acutely ill and, on physical examination, found to have a diffuse erythematous rash extending to palms and soles. She is confused. Initial blood tests are as follows: White blood cell count: 22,000/μL Na+: 125 mEq/L K+: 3.0 mEq/L Ca++: 8.0 mEq/mL Activated partial thromboplastin time (PTT): 65 (normal 21 to 36) Prothrombin time (PT): 12s (normal < 15s) Aspartate aminotransferase: 240 U/L (normal < 40) Creatinine: 3.0 mg/dL Antinuclear antibodies: negative Anti-DNA antibodies: negative Serologic tests for RMSF, leptospirosis, measles: negative Which of the following best describes the pathophysiology of the disease process?

102. You are a physician in charge of patients who reside in a nursing home. Several of the patients have developed influenza-like symptoms, and the community is in the midst of influenza A outbreak. None of the nursing home residents have received the influenza vaccine. Which course of action is most appropriate?

103. A 21-year-old woman visits her physician because of 3 weeks of a flu-like‖ illness. She reports symptoms of malaise, fever, fatigue, and a sore throat. There is no weight loss or night sweats, and she has not traveled out of country. Her past medical history is not significant and she is not taking any medications. Physical examination is normal except for enlarged cervical lymph nodes. Laboratory data show hemoglobin 13.2 g/dL; hematocrit 42%; platelets 380,000/mL; WBC 8500/mL, with 35% segmented neutrophils, 1% eosinophils, and 64% lymphocytes, of which 36% were atypical. A heterophil antibody (sheep cell agglutination) test is negative. Which of the following is the most likely causative organism?

104. A 4-year-old boy is sent to the emergency room because of clinical suspicion of meningitis. He has been ill for 2 days with fever and lethargy. On examination, he is febrile, the neck is stiff, and papilledema is present. There is no rash, the lungs are clear, and heart sounds normal. Which of the following is the most likely causative organism?

105. A 24-year-old woman presents with chills and rigors. She looks unwell, and her temperature is 39.4C, blood pressure 100/60 mm Hg, pulse 110/min, and oxygen saturation 95%. There is a 3/6 pansystolic murmur at the right sternal border, which increases with inspiration. Her arms have multiple tattoos and needle marks from injection drug use. Blood cultures (2/2 sets) are positive for S. aureus, and she is started on appropriate antibiotics. Her renal function is mildly impaired and her urinalysis is positive for protein, and microscopy reveals red cell casts. Which of the following mechanisms is the most likely explanation for her renal abnormalities?

106. A 22-year-old university student complains of fatigue and malaise for the past 2 weeks. She also reports feeling feverish, and recently had a sore throat. Physical examination reveals enlarged tonsils and palpable cervical lymph nodes. There is also tenderness in the right upper quadrant on deep palpation, and minimal splenomegaly. Laboratory data show hemoglobin 13 g/dL; hematocrit 40%; platelets 340,000/mL; WBC 9400/mL, with 35% segmented neutrophils, 1% eosinophils, and 64% lymphocytes, of which 36% were atypical. A heterophil antibody (sheep cell agglutination) test is positive. Which of the following is the most appropriate initial treatment for this condition?

107. A 30-year-old male with sickle cell anemia is admitted with cough, rusty sputum, and a single shaking chill. Physical examination reveals increased tactile fremitus and bronchial breath sounds in the left posterior chest. The patient is able to expectorate a purulent sample. Which of the following best describes the role of sputum Gram stain and culture?

108. A recent outbreak of severe diarrhea is currently being investigated. Several adolescents developed bloody diarrhea, and one remains hospitalized with acute renal failure. A preliminary investigation has determined that all the affected ate at the same restaurant. The food they consumed was most likely to be which of the following?

109. A 23-year-old woman presents with a painless chronic vulvar ulcer. She recently arrived to study in the United States from Southern India. The lesion began as a papule and then ulcerated. It has persisted for several months. Currently, physical examination reveals a painless elevated area of beefy red, friable granulation tissue. She has been sexually active for several years. Which of the following is the most likely causative organism?

110. A 20-year-old woman presents with headache, fever, and neck stiffness. On examination, her blood pressure is 100/70 mm Hg, pulse 100/min, temperature 38.6C, and the neck is stiff and painful to flex and extend. The ears, throat, and sinuses are normal, there are no focal neurologic signs, and the remaining examination is normal. There are no reported similar cases in the community. Which of the following is the most likely source of her infection?

111. A 44-year-old renal transplant patient develops severe cough and shortness of breath on exertion. On examination, he appears dyspneic, respirations 24/min, pulse 110/min, and oxygen saturation 88%. His lungs are clear on auscultation and heart sounds are normal. CXR shows bilateral diffuse perihilar infiltrates. Bronchoscopy and bronchial brushings show clusters of cysts that stain with methenamine silver. Which of the following is the most appropriate next step in management?

112. A 32-year-old woman acutely develops high fever, hypotension, and rash. This is followed by vomiting, diarrhea, confusion, and abdominal pain. In the hospital, evidence of multiorgan failure develops. Desquamation of the skin occurs 1 week after the acute illness. On further history, the illness started 3 days after the onset of menstruation. Which of the following is the most likely diagnosis?

113. An 18-year-old man develops fever, neck stiff- ness, and headache. On examination, his blood pressure is 105/80 mm Hg, pulse 100/min, temperature 38.7C, and neck flexion is very painful. The ears, throat, and sinuses are normal; there are no focal neurologic signs, and the remaining examination is normal. His is the second case of meningitis in his university dormitory building. Which of the following is the most likely causative organism?

114. A businesswoman needs to make frequent trips to South America, but every time she is there, she develops traveler’s diarrhea, which requires her to change her business schedule. To prevent future episodes during business trips, she is inquiring about prophylaxis methods. Which of the following is the most helpful advice for her?

116. A 19-year-old woman was traveling in a rural area of South America. She returned 3 weeks ago and, over the past few days, has gradually developed lower abdominal pain and diarrhea. Now the symptoms are much worse with 10 stools a day consisting mostly of mucus and blood. She is afebrile, the abdomen is tender in left lower quadrant, and the remaining examination is normal. Her stool is mostly comprised of blood and mucus. Which of the following is the most likely causative organism?

117. An 18-year-old man develops fever, neck stiffness, and headache. On examination, his blood pressure is 110/80 mm Hg, pulse 100/min, temperature 38.7C, and neck flexion is very painful. The  ears, throat, and sinuses are normal; there are no focal neurologic signs; and the remaining examination is normal. There are no reported similar cases in the community. Which of the following is the most likely causative organism?

118. A 21-year-old man presents with symptoms of headache, fever, chills, and discomfort in both sides of his jaw. He has also noticed discomfort in his testes, but no dysuria or urethral dis- charge. Physical examination reveals bilateral enlargement of the parotid glands, as well as bilateral testicular enlargement and tenderness on palpation. His temperature is 38.5°C pulse rate of 92/min, and the remaining examination is normal. Laboratory data show hemoglobin 15 g/dL; hematocrit 40%; WBC 12000/mL, with 30% segmented neutrophils, 8% monocytes, and 62% lymphocytes. Which of the following statements concerning this disease is true?

119. A 22-year-old man is an avid spelunker (cave explorer) and has recently been exploring several caves. A routine CXR taken for a new job reveals hilar adenopathy and two patches of pneumonitis. His physical examination is completely normal. Careful questioning reveals he has just gotten over a cold with mild fever, cough, and malaise. Which of the following is the most likely diagnosis?

120. A previously well 28-year-old female has developed gradual onset of fever and malaise over 2–3 weeks. She also complains of arthralgias and myalgias. Repeated measurement of her temperature reveals a low grade fever between 38C and 39C. Physical examination reveals an oval retinal hemorrhage with a clear, pale center; a pansystolic cardiac murmur heard best at the apex; and small, tender nodules on her fingertips. Which of the following is the most likely causative organism?

121. A 30-year-old male patient complains of fever and sore throat for several days. The patient presents to you today with additional complaints of hoarseness, difficulty breathing, and drooling. On examination, the patient is febrile and has inspiratory stridor. Which of the following is the best course of action?

122. A 70-year-old patient with long-standing type 2 diabetes mellitus presents with complaints of pain in the left ear with purulent drainage. On physical examination, the patient is afebrile. The pinna of the left ear is tender, and the external auditory canal is swollen and edematous. The white blood cell count is normal. Which of the following organisms is most likely to grow from the purulent drainage?

123. A 53-year-old man with alcoholic cirrhosis presents with increasing jaundice and abdominal discomfort. He reports no fevers or chills. On examination, his blood pressure is 100/60 mm Hg, pulse 100/min, temperature 38.1C. He has a distended abdomen, peripheral edema, and shifting dullness. The abdomen is tender and bowel sounds are present. A diagnostic paracentesis is performed; the total cell count is 940/mL with polymorphonuclear neutrophils (PMNs) equal to 550/mL, Gram stain is negative, and cultures are pending. Which of the following is the most likely diagnosis?

124. A 20-year-old woman presents with headache, anorexia, chilly sensations, pain, and drawing sensations in both sides of her jaw. She has also noticed discomfort in both lower abdominal quadrants. Physical examination reveals bilateral enlarged parotid glands that are doughy, elastic, and slightly tender; with a reddened orifice of Stensen’s duct. Her abdomen is soft with bilateral lower quadrant abdominal tenderness, a temperature of 38.5°C, and a pulse rate of 92/min. Laboratory data show hemoglobin 13 g/dL; hematocrit 40%; WBC 9000/mL, with 35% segmented neutrophils, 7% monocytes, and 58% lymphocytes. Which of the following is the most likely diagnosis?

125. An 18-year-old woman visits her physician because of 3 weeks of malaise, 2 weeks of fever, and a sore throat. Physical examination shows pharyngeal infection with enlarged tonsils and a patchy, white exudate; enlarged, palpable anterior and posterior cervical, axillary, and inguinal lymph nodes; tenderness in the right upper quadrant; and minimal splenomegaly. Laboratory data show hemoglobin 14 g/dL; hematocrit 42%; platelets 380,000/mL; WBC 8500/mL, with 35% segmented neutrophils, 1% eosinophils, and 64% lymphocytes, of which 36% were atypical. Which of the following is the most likely diagnosis?

126. A 25-year-old male student presents with the chief complaint of rash. He denies headache, fever, or myalgia. A slightly pruritic maculopapular rash is noted over the abdomen, trunk, palms of the hands, and soles of the feet. Inguinal, occipital, and cervical lymphadenopathy is also noted. Hypertrophic, flat, wart like lesions are noted around the anal area. Laboratory studies show the following: Hct: 40% Hgb: 14 g/dL WBC: 13,000/μL Diff: 50% segmented neutrophils, 50% lymphocytes Which of the following is the most useful laboratory test in this patient?

127. A previously healthy 19-year-old female university student develops myalgia, headache, fever, and malaise. Blood tests reveal lymphocytosis, with 20% of the lymphocytes being atypical. She remains tired and unwell for 6 weeks, but repeated tests for heterophil antibody are negative. Which of the following is the most likely diagnosis?

128. A 43-year-old man developed a cough shortly after returning from a 1-month hiking trip in California. While there, he was hiking in the central California valleys. During his trip, he had developed a flu-like‖ illness consisting of fever, cough, and muscle pains, which resolved spontaneously. A CXR shows a thin-walled cavity in the right upper lobe, and the sputum reveals fungal elements. Which of the following is the most likely causative organism?

129. An 8-year-old boy from an impoverished inner- city area has never been vaccinated appropriately. He develops fever, cough, and coryza. The next day, blue white spots develop on the buccal mucosa. On the third day, an erythematous, nonpruritic maculopapular rash develops on the face and spreads over the entire body. Which of the following is the most likely complication?

130. A 6-year-old boy develops symptoms of cough, fever, and malaise followed by a generalized maculopapular rash that has spread from the head downwards. A clinical diagnosis of measles is made. A few days after the onset of the rash he is drowsy, lethargic, and complaining of headache. A lumbar puncture, electroencephalogram (EEG), and computerized tomography (CT) of the brain exclude other etiologies and confirm the diagnosis of encephalitis. Which of the following is the most likely delayed neurologic complication of measles virus encephalitis?

131. A 35-year-old previously healthy male develops cough with purulent sputum over several days. On presentation to the emergency room, he is lethargic. Temperature is 39°C, pulse 110, and blood pressure 100/70. He has rales and dullness to percussion at the left base. There is no rash. Flexion of the patient’s neck when supine results in spontaneous flexion of hip and knee. Neurologic examination is otherwise normal. There is no papilledema. A lumbar puncture is performed in the emergency room. The cerebrospinal fluid (CSF) shows 8000 leukocytes/μL, 90% of which are polys. Glucose is 30 mg/dL with a peripheral glucose of 80 mg/dL. CSF protein is elevated to 200 mg/dL. A CSF Gram stain shows gram-positive diplococci. Which of the following is the correct treatment option?

132. A 20-year-old female college student presents with a 5-day history of cough, low-grade fever (temperature 37.8°C (100°F), sore throat, and coryza. On examination, there is mild conjunctivitis and pharyngitis. Tympanic membranes are inflamed, and one bullous lesion is seen. Chest examination shows a few basilar rales. Sputum Gram stain shows white blood cells without organisms. Laboratory findings are as follows: Hct: 31 WBC: 12,000/μL Lymphocytes: 50% Mean corpuscular volume (MCV): 94 nL Reticulocytes: 9% of red cells CXR: bilateral patchy lower lobe infiltrates Which of the following is the best method for confirmation of the diagnosis?

133. Three hours after a church social, eight people develop severe diarrhea. Other symptoms included nausea, vomiting, and abdominal cramps. Food served included chicken salad and cream-filled pastries. All affected individuals had the chicken salad. Which of the following is the most likely causative organism?

134. A 9-year-old boy has a severe sore throat with fever and dysphagia. On examination, there are grayish-white papulovesicular lesions on an erythematous base that ulcerate. They are located on the soft palate, anterior pillars of the tonsils and uvula. There are no lesions on the gingiva, tongue, or lips. A clinical diagnosis of herpangina is made. Which of the following is the most likely causative organism?

135. A young man has recently been bitten by a stray dog. He has a penetrating wound to the right forearm. The dog is nowhere to be found. In the emergency room, the wound is cleaned with water and povidone-iodine solution. Which of the following is the most appropriate next step in management?

136. A 24-year-old man complains of fatigue, malaise, fever, and a sore throat. He was previously well, but now feels tired all the time and has to rest multiple times a day. Physical examination shows enlarged tonsils and palpable anterior and posterior cervical, axillary, and inguinal lymph nodes. There is also tenderness in the right upper quadrant with a liver span of 10 cm. Laboratory data is significant for a heterophil antibody (sheep cell agglutination) test that is positive. Which of the following rare complications can be associated with this condition?

137. A 22-year-old male, recently incarcerated and now homeless, has received one week of clarithromycin for low-grade fever and left upper-lobe pneumonia. He has not improved on antibiotics, with persistent cough productive of purulent sputum and flecks of blood. Repeat chest x- ray suggests a small cavity in the left upper lobe. Which of the following statements is correct?

138. A 34-year-old man presents with diarrhea 3 weeks after returning from a trip to rural South America. Over the past few days, he has gradually developed lower abdominal pain and diarrhea. Now the symptoms are much worse with eight stools a day consisting mostly of mucus and blood. He is afebrile, the abdomen is tender in left lower quadrant, and the remaining examination is normal. His stool is mostly comprised of blood and mucus, and stools tests show trophozoites of Entamoeba hitolytica. Which of the following is the most likely site of extraintestinal involvement?

139. A 20-year-old woman complains of headache and discomfort in both sides of her jaw. Physical examination reveals enlarged parotid glands that are slightly tender on palpation. There is reddening of the orifice of Stensen’s duct on intra oral examination; her temperature is 38.3°C, and the pulse rate is 80/min. Laboratory data show hemoglobin 14 g/dL; hematocrit 40%; WBC 11000/mL, with 33% segmented neutrophils, 7% monocytes, and 60% lymphocytes. Which of the following diagnostic tests will help to confirm the diagnosis of epidemic parotitis?

140. A 40-year-old man develops erythema nodosum, conjunctivitis, and a pleural effusion. Over several weeks, pulmonary lesions lead to cavitation and a large, thin-walled cavity. He was traveling in Arizona before becoming ill. Sputum samples reveal mature spherules. Which of the following is the most likely diagnosis?

141. A 19-year-old male presents with a 1-week history of malaise and anorexia followed by fever and sore throat. On physical examination, the throat is inflamed without exudate. There are a few palatal petechiae. Cervical adenopathy is present. The liver span is 12 cm and the spleen is palpable. Throat culture: negative for group A streptococci Hgb: 12.5, Hct: 38% Reticulocytes: 4% WBC: 14, 000/μL Segmented: 30% Lymphocytes: 60% Monocytes: 10% Bilirubin total: 2.0 mg/dL (normal 0.2 to 1.2) Lactic dehydrogenase (LDH) serum: 260 IU/L (normal 20 to 220) Aspartate aminotransferase (AST): 40 U/L (normal 8 to 20 U/L) Alanine aminotransferase (ALT): 35 U/L (normal 8 to 20 U/L) Alkaline phosphatase: 40 IU/L (normal 35 to 125) Which of the following is the most important initial test combination to order?

142. A 23-year-old woman visits your office because of headache, malaise, anorexia, pain in both sides of her jaw, and discomfort in both lower abdominal quadrants. Physical examination reveals enlarged parotid glands; bilateral lower quadrant abdominal tenderness; a temperature of 38.7°C; and a pulse rate of 92/min. Serologic testing (IgM) confirms the diagnosis of mumps. Which of the following is the most appropriate treatment for this condition?

143. A 10-year-old boy presents with fever, headache, photophobia, and neck discomfort in the middle of summer. He is alert and oriented, but has neck pain with flexion and extension of the head. His fundi are normal, and there are no focal neurologic findings or skin changes. A lumbar puncture reveals normal protein and glucose with a cell count of 240/mL (90% lymphocytes). Which of the following is the most likely causative organism?

144. A 27-year-old man presents with diarrhea. He returned 3 weeks ago from a trip to rural South America. Over the past few days, he has gradually developed lower abdominal pain and diarrhea. Now the symptoms are much worse with eight stools a day consisting mostly of mucus and blood. He is afebrile, the abdomen is tender in left lower quadrant, and the remaining examination is normal. His stool is mostly comprised of blood and mucus. Which of the following is the most appropriate initial diagnostic test?

145. A 25-year-old woman complains of dysuria, frequency, and suprapubic pain. She has not had previous symptoms of dysuria and is not on antibiotics. She is sexually active and on birth control pills. She has no fever, vaginal discharge or history of herpes infection. She denies back pain, nausea, or vomiting. On physical examination she appears well and has no costovertebral angle tenderness. A urinalysis shows 20 white blood cells per high power field. Which of the following statements is correct?

146. A 60-year-old male complains of low back pain, which has intensified over the past 3 months. He had experienced some fever at the onset of the pain. He was treated for acute pyelonephritis about 4 months ago. Physical examination shows tenderness over the L2-3 vertebra and paraspinal muscle spasm. Laboratory data show an erythrocyte sedimentation rate of 80 mm/h and elevated C-reactive protein. Which of the following statements is correct?

147. A 40-year-old school teacher develops nausea and vomiting at the beginning of the fall semester. Over the summer she had taught preschool children in a small town in Mexico. She is sexually active, but has not used intravenous drugs and has not received blood products. Physical examination reveals scleral icterus, right upper quadrant tenderness, and a palpable liver. Liver function tests show aspartate aminotransferase of 750 U/L (normal < 40) and alanine aminotransferase of 1020 U/L (normal < 45). The bilirubin is 13 mg/dL (normal < 1.4) and the alkaline phosphatase is normal. What further diagnostic test is most likely to be helpful?

149. A 7-year-old child, unvaccinated because of his parents’ religious beliefs, develops malaise, cough, coryza, and conjunctivitis with a high fever. Examination of his mouth reveals blue white spots on a red base beside his second molars. The next day he develops an erythematous, nonpruritic, maculopapular rash at his hairline and behind his ears, which spreads over his body. Which of the following is the most likely diagnosis?

150. A 60-year-old man presents with fever and malaise 6 weeks after mitral valve replacement. On examination, his temperature is 38C, blood pressure 130/80 mm Hg, pulse 80/min, and a loud pansystolic murmur at the apex, which radiates to the axilla. He has no skin or neurologic findings. Which of the following is the most likely causative organism?

151. A previously healthy 25-year-old music teacher develops fever and a rash over her face and chest. The rash is itchy and, on examination, involves multiple papules and vesicles in varying stages of development. One week later, she complains of cough and is found to have an infiltrate on x-ray. Which of the following is the most likely etiology of the infection

152. A 40-year-old woman cut her finger while cooking in her kitchen. Two days later she became rapidly ill with fever and shaking chills. Her hand became painful and mildly erythematous. Later that evening her condition deteriorated as the erythema progressed and the hand became a dusky red. Bullae and decreased sensation to touch developed over the involved hand. What is the most important next step in the management of this patient?

153. A 19-year-old male has a history of athlete’s foot but is otherwise healthy when he develops sudden onset of fever and pain in the right foot and leg. On physical examination, the foot and leg are fiery red with a well-defined indurated margin that appears to be rapidly advancing. There is tender inguinal lymphadenopathy. The most likely organism to cause this infection is which of the following?