LATEST INFECTIOUS DISEASE CERTIFICATION
EXAM FOR THE AMERICAN BOARD OF
INTERNAL MEDICINE (ABIM) | COMPLETE
EXAM Q&A WITH RATIONALES
1. A 45-year-old male with HIV (CD4 120) presents
with fever, nonproductive cough, and dyspnea for 2
weeks. Chest X-ray shows bilateral interstitial
infiltrates. Oxygen saturation is 88% on room air.
What is the most appropriate empiric therapy?
A) Trimethoprim-sulfamethoxazole (TMP-SMX)
B) Azithromycin
C) Fluconazole
D) Amphotericin B
Correct answer: A
Rationale: Suspected Pneumocystis jirovecii
pneumonia (PJP) in HIV with CD4 <200. Empiric TMP-
SMX while awaiting diagnostic confirmation
(bronchoscopy with BAL).
2. A 68-year-old male with a history of diabetes
presents with a 3-day history of fever, cough, and
purulent sputum. Chest X-ray shows right lower lobe
consolidation. He has no drug allergies. What is the
,most appropriate empiric antibiotic for outpatient
treatment?
A) Amoxicillin-clavulanate
B) Doxycycline
C) Levofloxacin
D) Cefdinir
Correct answer: B
Rationale: Uncomplicated community-acquired
pneumonia in outpatient without comorbidities:
amoxicillin or doxycycline. Doxycycline covers
atypicals. Fluoroquinolones reserved for failure or
comorbidities.
3. A 55-year-old male with HIV (CD4 350) presents
with headache, fever, and nuchal rigidity. Lumbar
puncture shows WBC 500 (80% lymphocytes),
glucose 40, protein 120. India ink stain is negative.
Cryptococcal antigen is negative. What is the most
likely organism?
A) Mycobacterium tuberculosis
B) Cryptococcus neoformans
C) Viral meningitis
D) Toxoplasma gondii
Correct answer: A
,Rationale: Chronic meningitis with lymphocytic
predominance, low glucose, elevated protein in HIV:
TB meningitis. India ink and cryptococcal antigen
negative rule out cryptococcus.
4. A 28-year-old female presents with acute dysuria,
frequency, and suprapubic pain. Urinalysis shows
100 WBCs, positive nitrites, and moderate bacteria.
She has no drug allergies. What is the most
appropriate antibiotic?
A) Nitrofurantoin 100 mg twice daily for 5 days
B) Ciprofloxacin 500 mg twice daily for 3 days
C) TMP-SMX twice daily for 3 days
D) Amoxicillin 500 mg three times daily for 7 days
Correct answer: A
Rationale: Uncomplicated cystitis: nitrofurantoin (5
days) or TMP-SMX (3 days) if local resistance <20%.
Fluoroquinolones reserved for complicated UTI or
pyelonephritis.
5. A 65-year-old male with end-stage renal disease on
hemodialysis presents with fever and chills. His
vascular access site is erythematous and tender.
Blood cultures drawn from the access and peripheral
vein. What is the most likely organism?
, A) Staphylococcus aureus
B) Coagulase-negative staphylococcus
C) Enterococcus faecalis
D) Pseudomonas aeruginosa
Correct answer: A
Rationale: Hemodialysis catheter-associated
bloodstream infection: most commonly S. aureus
(MRSA or MSSA). Coagulase-negative staph is often
contaminant.
6. A 35-year-old male with HIV (CD4 50) presents with
fever, headache, and new-onset seizures. MRI brain
shows multiple ring-enhancing lesions in the basal
ganglia. What is the most likely diagnosis?
A) Toxoplasma gondii
B) Primary CNS lymphoma
C) Tuberculoma
D) Cryptococcoma
Correct answer: A
Rationale: Toxoplasmosis (Toxoplasma gondii) in HIV
with CD4 <100: multiple ring-enhancing lesions in
basal ganglia. Treat empirically with pyrimethamine-
sulfadiazine.
EXAM FOR THE AMERICAN BOARD OF
INTERNAL MEDICINE (ABIM) | COMPLETE
EXAM Q&A WITH RATIONALES
1. A 45-year-old male with HIV (CD4 120) presents
with fever, nonproductive cough, and dyspnea for 2
weeks. Chest X-ray shows bilateral interstitial
infiltrates. Oxygen saturation is 88% on room air.
What is the most appropriate empiric therapy?
A) Trimethoprim-sulfamethoxazole (TMP-SMX)
B) Azithromycin
C) Fluconazole
D) Amphotericin B
Correct answer: A
Rationale: Suspected Pneumocystis jirovecii
pneumonia (PJP) in HIV with CD4 <200. Empiric TMP-
SMX while awaiting diagnostic confirmation
(bronchoscopy with BAL).
2. A 68-year-old male with a history of diabetes
presents with a 3-day history of fever, cough, and
purulent sputum. Chest X-ray shows right lower lobe
consolidation. He has no drug allergies. What is the
,most appropriate empiric antibiotic for outpatient
treatment?
A) Amoxicillin-clavulanate
B) Doxycycline
C) Levofloxacin
D) Cefdinir
Correct answer: B
Rationale: Uncomplicated community-acquired
pneumonia in outpatient without comorbidities:
amoxicillin or doxycycline. Doxycycline covers
atypicals. Fluoroquinolones reserved for failure or
comorbidities.
3. A 55-year-old male with HIV (CD4 350) presents
with headache, fever, and nuchal rigidity. Lumbar
puncture shows WBC 500 (80% lymphocytes),
glucose 40, protein 120. India ink stain is negative.
Cryptococcal antigen is negative. What is the most
likely organism?
A) Mycobacterium tuberculosis
B) Cryptococcus neoformans
C) Viral meningitis
D) Toxoplasma gondii
Correct answer: A
,Rationale: Chronic meningitis with lymphocytic
predominance, low glucose, elevated protein in HIV:
TB meningitis. India ink and cryptococcal antigen
negative rule out cryptococcus.
4. A 28-year-old female presents with acute dysuria,
frequency, and suprapubic pain. Urinalysis shows
100 WBCs, positive nitrites, and moderate bacteria.
She has no drug allergies. What is the most
appropriate antibiotic?
A) Nitrofurantoin 100 mg twice daily for 5 days
B) Ciprofloxacin 500 mg twice daily for 3 days
C) TMP-SMX twice daily for 3 days
D) Amoxicillin 500 mg three times daily for 7 days
Correct answer: A
Rationale: Uncomplicated cystitis: nitrofurantoin (5
days) or TMP-SMX (3 days) if local resistance <20%.
Fluoroquinolones reserved for complicated UTI or
pyelonephritis.
5. A 65-year-old male with end-stage renal disease on
hemodialysis presents with fever and chills. His
vascular access site is erythematous and tender.
Blood cultures drawn from the access and peripheral
vein. What is the most likely organism?
, A) Staphylococcus aureus
B) Coagulase-negative staphylococcus
C) Enterococcus faecalis
D) Pseudomonas aeruginosa
Correct answer: A
Rationale: Hemodialysis catheter-associated
bloodstream infection: most commonly S. aureus
(MRSA or MSSA). Coagulase-negative staph is often
contaminant.
6. A 35-year-old male with HIV (CD4 50) presents with
fever, headache, and new-onset seizures. MRI brain
shows multiple ring-enhancing lesions in the basal
ganglia. What is the most likely diagnosis?
A) Toxoplasma gondii
B) Primary CNS lymphoma
C) Tuberculoma
D) Cryptococcoma
Correct answer: A
Rationale: Toxoplasmosis (Toxoplasma gondii) in HIV
with CD4 <100: multiple ring-enhancing lesions in
basal ganglia. Treat empirically with pyrimethamine-
sulfadiazine.
