1.
A 4-year-old boy presents to the pediatric emergency department with the classic meningitis triad of fever, headache, and nuchal rigidity. A lumbar puncture is performed and analysis of the fluid shows an increase in polymorphonuclear cells, an increased protein level, and a decreased glucose level. Which of the following is the most common cause of meningitis in a child of this age with this clinical picture?
A. 
B. 
Haemophilus infl uenzae type B
C. 
D. 
E. 
2.
A 32-year-old man presents to his doctor with painful urination and a purulent urethral discharge. The image shows cells that have been cultured from this discharge. Which of the following is the treatment of choice for this infection?
A. 
B. 
C. 
D. 
E. 
3.
A 43-year-old man presents with fl u-like symptoms, fevers, chills, and a productive cough. Physical examination is remarkable for pleuritic chest pain. On questioning, the patient says that he has just spent the last week on vacation in Central America. Cultures taken from the patient show a broad-based budding fungus. It is concluded that the man has systemic blastomycosis infection. Which of the following agents is the most appropriate treatment for this patient?
A. 
B. 
C. 
Itraconazole or potassium iodide
D. 
Sodium stibogluconate only
E. 
Topical miconazole or selenium sulfide
4.
73-year-old woman steps on a rusty nail while gardening in her back yard. A neighbor drives her to the emergency department, where her wound is cleaned and bandaged. A complete history and review of her medical chart indicates that her vaccinations are not up to date, and she requires one vaccination and a shot of the appropriate immunoglobulin as prophylaxis against infection. What is the mechanism of toxicity of the organism for which she was vaccinated?
A. 
ADP-ribosylation of a G protein, increasing chloride secretion
B. 
ADP-ribosylation of an elongation factor, causing disrupted protein synthesis
C. 
Binding to the MHC II receptor and T-lymphocyte receptor, causing cytokine synthesis
D. 
Blocking release of the inhibitory neurotransmitter
glycine
E. 
Blocking the release of acetylcholine
F. 
G. 
Stimulation of guanylate cyclase
5.
A 50-year-old man develops nonbloody watery diarrhea while working as an aid worker in a refugee camp in Bangladesh. He arrived in the area 2 days ago. A stool smear shows no WBCs. He subsequently develops dehydration and electrolyte abnormalities leading to cardiac and renal failure. Which of the following organisms is the most likely cause of this man’s enterocolitis?
A. 
B. 
C. 
D. 
E. 
6.
Twenty-four hours after placement of a catheter,
a hospitalized patient develops a fever and
chills. Within 1 hour her systolic blood pressure
falls 30 points and she develops swelling
in her extremities. Despite valiant efforts by the
hospital staff, the patient dies. X-ray of the patient’s
lungs taken only hours before she passed
away shows pulmonary edema. Which of the
following mediators of this patient’s disease
process is most likely responsible for the pathology
described?
A. 
B. 
C. 
D. 
E. 
F. 
7.
A 31-year-old pregnant woman comes to the
physician because of painful vesicular lesions
that have recently appeared on her genitalia. A
positive result on which of the following diagnostic
tests would mean that her baby is at risk
for congenital anomalies?
A. 
Anti-hepatitis B surface antibody test
B. 
Giemsa stain for cytoplasmic inclusions
C. 
D. 
Tzanck smear for multinucleated giant
cells
E. 
8.
A 13-year-old girl who returned a few days ago
from a school camping trip in North Carolina
is home ill from school. She tells her parents
that she has a headache and the chills. Over
the next few days, she develops a rash that begins
on her palms and soles, but spreads inward
to her wrists and ankles and then to her
trunk. Her worsening condition leads her parents
to take her to the emergency department,
where a blood test reveals antibodies that react
with the Proteus antigen. This patient is most
likely infected with which of the following?
A. 
B. 
C. 
D. 
E. 
F. 
9.
A 53-year-old obese man with poorly controlled
non-insulin-dependent diabetes mellitus presents
with fever to 39.6° C (103.2° F), jaundice,
hypotension, and acute onset of right upper
quadrant pain. Right upper quadrant imaging
shows multiple gallstones and cholecystitis. Urgent
cholecystectomy is performed, and subsequent
gall bladder fl uid and blood cultures
grow aerobic, non-lactose-fermenting, oxidasepositive,
gram-negative rods. Blood tests show:
Hematocrit: 29%
WBC count: 14,700/mm3
Platelet count: 76,000/mm3
D-dimer: 8500 ng/mL
Fibrinogen levels: low
Microscopic inspection of peripheral blood
smear shows schistocytes and multiple helmet
cells. Clinically, there is no evidence of active
bleeding. What is the most appropriate treatment
for this patient’s coagulopathy?
International Normalized Ratio: 3.2
A. 
B. 
C. 
D. 
E. 
10.
A 22-year-old woman presents to the physician
with vaginal itching and burning. On examination,
she has a foul-smelling greenish discharge.
A swab sample is taken and a wet
mount slide is prepared; results are shown in
the image. Which of the following medications
should be prescribed for this patient?
A. 
B. 
C. 
D. 
E. 
Sulfadiazine and pyrimethamine
11.
A 40-year-old man goes on a camping vacation
with his family. One day after swimming in a
freshwater lake near the camp site, he develops
nausea and vomiting and starts to behave irrationally.
His family takes him to the emergency
department, where blood samples are taken
and a spinal tap is performed. He is diagnosed
with a rapidly progressing meningoencephalitis
and dies shortly thereafter. Which of the following
protozoa was most likely the cause of
the man’s illness?
A. 
B. 
C. 
D. 
E. 
12.
A 54-year-old man presents to the clinic with
scleral icterus, hepatosplenomegaly, ascites,
and a history of episodes of jaundice over the
past 3 years. He was involved in an auto accident
when he was 21 years old, for which he
required surgery and blood transfusions. Laboratory
tests show:
Aspartate aminotransferase: 734 U/L
Alanine aminotransferase: 846 U/L
Direct bilirubin: 0.1 mg/dL
Indirect bilirubin: 7.6 mg/dL
Assuming a viral etiology, which of the following
is the most likely cause of this patient’s illness?
A. 
B. 
C. 
D. 
E. 
13.
A 19-year-old college student presents to his
family physician with a 1-week history of fever,
headache, and painful exudative pharyngitis.
Physical examination shows signifi cant lymphadenopathy
of the cervical nodes and hepatosplenomegaly.
Laboratory studies show a WBC
count of 15,000/mm3 with 55% lymphocytes.
A heterophile antibody test is positive. Which
of the following is the most likely cause of this
patient’s symptoms?
A. 
B. 
C. 
D. 
E. 
14.
A 36-year-old man comes to the physician
complaining of an aching back, high fever, and
vomiting of dark material. He is obviously ill
and states that he has felt very poorly for approximately
1 week. Physical examination
shows that the patient has a temperature of
39° C (102.2° F) and icteric sclera. The patient
recently returned from a trip on safari in
Africa. If a liver biopsy were done, it would
show the following pathology. What are the
names of the eosinophilic globules shown in
this image?
A. 
B. 
C. 
D. 
E. 
15.
A 56-year-old man presents to the emergency
department with sharp retrosternal pain radiating
to his back and arms. The patient is sitting
up and leaning forward. He states that the pain
is less severe in this position and worsens when
he lies down and takes a deep breath. He also
indicates that he recently recovered from a fever
and a cold. On physical examination a
scratchy, leathery sound is heard at the lower
left sternal border. An ECG is done and confi
rms the diagnosis. Which of the following microorganisms
is the most likely cause of this
condition?
A. 
B. 
C. 
D. 
E. 
16.
A 28-year-old man comes to the physician because
of worsening muscle weakness that began
in his legs and feet 3 days ago, and has now
spread to his arms and hands. Other than having
a fl u-like illness 2 weeks ago, the patient
has been in good health. Cerebrospinal fl uid
analysis shows an increased protein concentration,
a normal cell count, and a normal glucose
level. An infection with which of the following
organisms is the most likely cause of the
nervous system syndrome described in this patient?
A. 
B. 
C. 
D. 
E. 
17.
A 55-year-old man comes to his physician with
a tender, swollen, and erythematous left knee.
He has limited range of motion in his leg. On
aspiration of the synovial fl uid from his knee,
the fl uid is found to be yellow and cloudy and
has 150,000 neutrophils/mm3. Gram stain of
the aspirate shows gram-positive cocci in clusters.
The organism most likely responsible for
this patient’s symptoms has which of the following
properties?
A. 
Catalase-positive and coagulase-negative
B. 
Catalase-positive and coagulase-positive
C. 
D. 
E. 
18.
A family who recently emigrated from Romania
brings their 7-year-old child to the pediatrician
with complaints of conjunctivitis and periorbital
swelling. The child has had coughing
with a runny nose and high fever for 3 days.
Small lesions with blue-white centers are seen
in his oral cavity. Which of the following is the
most likely cause of this child’s symptoms?
A. 
B. 
C. 
D. 
E. 
19.
A 34-year-old woman newly diagnosed with
HIV infection is unable to access antiretroviral
medications. She is aware that if untreated, her
disease will progress and make her susceptible
to different infections. She inquires about the
natural course her disease may take and the
different infections she might acquire. Which
of the following conditions is most likely to
manifest only when the T cell count drops below
50/mm3?
A. 
Disseminated Mycobacterium aviumintracellulare
B. 
Herpes simplex virus infection
C. 
D. 
E. 
Pneumonia due to Pneumocystis jiroveci
F. 
Toxoplasmosis brain lesion
20.
An 8-year-old boy is brought to his pediatrician
by his parents because of a fever and a sore
throat. On examination, he has tonsillar exudates
and swollen, tender anterior cervical
nodes. His parents report no history of cough.
Gram stain of the tonsillar exudate reveals
gram-positive cocci. Which of the following
describes the organism most likely causing this
patient’s symptoms?
A. 
Catalase-negative, α-hemolytic, optochinresistant
B. 
Catalase-negative, α-hemolytic, optochinsensitive
C. 
Catalase-negative, β-hemolytic, bacitracinresistant
D. 
Catalase-negative, β-hemolytic, bacitracinsensitive
E. 
Catalase-positive, coagulase-negative, novobiocin-
resistant
F. 
Catalase-positive, coagulase-negative, novobiocin-
sensitive