VII. 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?
A. Chest X-ray
B. Observation
C. Isoniazid for 6 months
D. Isoniazid with pyridoxine for 9 months
E. Isoniazid, rifampin and pyrazinamide for 8 weeks
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?
A. Trichinellosis
B. Botulism
C. Infective endocarditis
D. Guillain-Barre syndrome
E. Angioedema
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?
A. Neurocysticercosis
B. Lymphoma
C. Metastatic brain tumor
D. Glioblastoma multiforme
,E. Tuberculoma of the brain
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?
A. Escherichia coli
B. Pseudomonas species
C. Salmonella species
D. Staphylococcus aureus
E. Group B streptococcus
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?
A. Trimethoprim-sulfamethoxazole
B. Oseltamivir
C. ltraconazole
D. Azithromycin
E. Penicillin
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?
A. Clostridium difficile colitis
B. E coli infection
C.lnflammatory bowel disease
D. Protozoal infection
E. Vibrio infection
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?
A. Reassurance and repeat testing in 2 months
B. Isoniazid and pyridoxine for 9 months
C. Rifampin for 9 months
D. Rifampin, isoniazid, pyrazinamide, and ethambutol for 2 months, then isoniazid and rifampin for
4 months
E. Rifampin, isoniazid, and pyrazinamide for 6 months
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?
A. Reassurance
B. Explain the risks and benefits of abortion
C. Advise abortion
D. Serological testing for rubella
E. Ultrasonography
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?
A. Ceftriaxone
B. Ceftriaxone and vancomycin
C. Cefotaxime and ampicillin
D. Ceftriaxone, vancomycin, and ampicillin
E. Ceftazidime and vancomycin
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?
A. BCG vaccine
B. Hepatitis A vaccine
C. Hepatitis B vaccine
D. Pneumococcal vaccine
E. Meningococcal vaccine
, 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?
A. Stop ceftriaxone and start piperacillin-tazobactam
B. Continue ceftriaxone and add vancomycin
C. Stop ceftriaxone and start clindamycin
D. Continue ceftriaxone and add ceftazidime
E. Continue ceftriaxone and add amphotericin
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?
A. Prednisone
B. Acyclovir
C. Pentamidine
D. Ganciclovir
E. ltraconazole
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?
A. Perform ELISA for confirmation of Lyme disease
B. Perform western blot for confirmation of Lyme disease
C. Give him oral doxycycline
D. Give him oral amoxicillin
E. Give him intravenous ceftriaxone
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?
A. Groupe B streptococci
B. Streptococcus mutans
C. Streptococci bovis
D. Staphylococcus epidermis
E. Enterococci
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?
A. Chest X-ray
B. Observation
C. Isoniazid for 6 months
D. Isoniazid with pyridoxine for 9 months
E. Isoniazid, rifampin and pyrazinamide for 8 weeks
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?
A. Trichinellosis
B. Botulism
C. Infective endocarditis
D. Guillain-Barre syndrome
E. Angioedema
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?
A. Neurocysticercosis
B. Lymphoma
C. Metastatic brain tumor
D. Glioblastoma multiforme
,E. Tuberculoma of the brain
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?
A. Escherichia coli
B. Pseudomonas species
C. Salmonella species
D. Staphylococcus aureus
E. Group B streptococcus
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?
A. Trimethoprim-sulfamethoxazole
B. Oseltamivir
C. ltraconazole
D. Azithromycin
E. Penicillin
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?
A. Clostridium difficile colitis
B. E coli infection
C.lnflammatory bowel disease
D. Protozoal infection
E. Vibrio infection
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?
A. Reassurance and repeat testing in 2 months
B. Isoniazid and pyridoxine for 9 months
C. Rifampin for 9 months
D. Rifampin, isoniazid, pyrazinamide, and ethambutol for 2 months, then isoniazid and rifampin for
4 months
E. Rifampin, isoniazid, and pyrazinamide for 6 months
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?
A. Reassurance
B. Explain the risks and benefits of abortion
C. Advise abortion
D. Serological testing for rubella
E. Ultrasonography
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?
A. Ceftriaxone
B. Ceftriaxone and vancomycin
C. Cefotaxime and ampicillin
D. Ceftriaxone, vancomycin, and ampicillin
E. Ceftazidime and vancomycin
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?
A. BCG vaccine
B. Hepatitis A vaccine
C. Hepatitis B vaccine
D. Pneumococcal vaccine
E. Meningococcal vaccine
, 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?
A. Stop ceftriaxone and start piperacillin-tazobactam
B. Continue ceftriaxone and add vancomycin
C. Stop ceftriaxone and start clindamycin
D. Continue ceftriaxone and add ceftazidime
E. Continue ceftriaxone and add amphotericin
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?
A. Prednisone
B. Acyclovir
C. Pentamidine
D. Ganciclovir
E. ltraconazole
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?
A. Perform ELISA for confirmation of Lyme disease
B. Perform western blot for confirmation of Lyme disease
C. Give him oral doxycycline
D. Give him oral amoxicillin
E. Give him intravenous ceftriaxone
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?
A. Groupe B streptococci
B. Streptococcus mutans
C. Streptococci bovis
D. Staphylococcus epidermis
E. Enterococci
