PANCE Infectious Disease 1 — Questions and Answers
Question 1: A 25-year-old male presents with fever, headache, photophobia, and nuchal rigidity. CSF analysis shows WBC 1,200 cells/µL (predominantly neutrophils), glucose 30 mg/dL (serum glucose 90 mg/dL), and protein 180 mg/dL. What is the most likely causative organism in this age group?
- Neisseria meningitidis (Correct answer)
- Streptococcus pneumoniae
- Listeria monocytogenes
- Haemophilus influenzae
Correct answer: Neisseria meningitidis
Neisseria meningitidis is the most common cause of bacterial meningitis in adolescents and young adults (15–24 years), particularly in college dormitory settings.
Question 2: A 35-year-old HIV-positive patient with a CD4 count of 50 cells/µL presents with headache, altered mental status, and a positive India ink stain of the CSF. Which medication is first-line induction therapy?
- Fluconazole
- Amphotericin B plus flucytosine (Correct answer)
- Voriconazole
- Caspofungin
Correct answer: Amphotericin B plus flucytosine
Amphotericin B plus flucytosine is the standard induction therapy for cryptococcal meningitis in HIV-positive patients, providing fungicidal activity.
Question 3: A 45-year-old farmer in Ohio presents with fever, chills, and a dry cough after cleaning a chicken coop. Chest X-ray shows hilar lymphadenopathy and diffuse small nodular infiltrates. Urine antigen test is positive. What is the diagnosis?
- Blastomycosis
- Coccidioidomycosis
- Histoplasmosis (Correct answer)
- Aspergillosis
Correct answer: Histoplasmosis
Histoplasmosis is endemic in the Ohio and Mississippi River valleys, spread by bird/bat droppings; urine antigen testing is the diagnostic method of choice.
Question 4: A patient presents with a painless penile ulcer with clean base and raised indurated edges. Dark-field microscopy of the lesion reveals spirochetes. Which antibiotic is first-line treatment?
- Doxycycline 100 mg PO BID × 14 days
- Azithromycin 1 g PO single dose
- Penicillin G benzathine 2.4 million units IM single dose (Correct answer)
- Ceftriaxone 500 mg IM single dose
Correct answer: Penicillin G benzathine 2.4 million units IM single dose
Primary syphilis caused by Treponema pallidum is treated with a single IM dose of penicillin G benzathine 2.4 million units.
Question 5: A 28-year-old sexually active woman presents with dysuria, mucopurulent cervical discharge, and cervical motion tenderness. Nucleic acid amplification test is positive for Chlamydia trachomatis. Which additional organism must empirically be treated simultaneously?
- Mycoplasma genitalium
- Neisseria gonorrhoeae (Correct answer)
- Trichomonas vaginalis
- Gardnerella vaginalis
Correct answer: Neisseria gonorrhoeae
Pelvic inflammatory disease (PID) treatment must cover both Chlamydia trachomatis and Neisseria gonorrhoeae empirically due to frequent co-infection.
Question 6: A 60-year-old patient who recently completed a 10-day course of antibiotics for a respiratory infection develops profuse watery diarrhea. Stool testing reveals the causative toxin. Which antibiotic is the preferred first-line treatment for mild-to-moderate disease?
- Metronidazole 500 mg PO TID × 10 days
- Vancomycin 125 mg PO QID × 10 days (Correct answer)
- Fidaxomicin 200 mg PO BID × 10 days
- Rifaximin 550 mg PO TID × 14 days
Correct answer: Vancomycin 125 mg PO QID × 10 days
Oral vancomycin 125 mg QID for 10 days is now the preferred first-line treatment for mild-to-moderate Clostridioides difficile infection per current IDSA guidelines.
Question 7: A 32-year-old hiker presents 3 weeks after returning from New England with a bull's-eye rash (erythema migrans), fever, and arthralgias. What is the most appropriate treatment?
- Azithromycin 500 mg PO daily × 7 days
- Amoxicillin 500 mg PO TID × 21 days
- Doxycycline 100 mg PO BID × 14–21 days (Correct answer)
- Ceftriaxone 2 g IV daily × 14 days
Correct answer: Doxycycline 100 mg PO BID × 14–21 days
Doxycycline is the first-line treatment for early Lyme disease (erythema migrans stage) in adults, given for 14–21 days.
PANCE Infectious Disease 1
A 25-year-old male presents with fever, headache, photophobia, and nuchal rigidity.
CSF analysis shows WBC 1,200 cells/µL (predominantly neutrophils), glucose 30 mg/dL (serum glucose 90 mg/dL), and protein 180 mg/dL.
What is the most likely causative organism in this age group?