FREE Internal Medicine Infectious Disease Principles Questions and Answers

Question 1

A 28-year-old male presents with a 3-day history of fever, severe headache, photophobia, and neck stiffness.
On examination, he is lethargic, has a temperature of 102.5°F (39.2°C), and a positive Brudzinski's sign.
A lumbar puncture is performed, and cerebrospinal fluid (CSF) analysis reveals a leukocyte count of 1200 cells/µL (90% neutrophils), glucose of 30 mg/dL (serum glucose 100 mg/dL), and protein of 180 mg/dL.
Which of the following is the most likely pathogen causing this presentation?

Accepted Answer

Streptococcus pneumoniae

Answer

Cryptococcus neoformans

Answer

Mycobacterium tuberculosis

Answer

Enterovirus

Question 2

Which of the following describes the primary mechanism by which broad-spectrum antibiotics can contribute to the development of Clostridioides difficile infection (CDI)?

Accepted Answer

Disrupting the normal gut microbiota, allowing C. difficile overgrowth.

Answer

Directly stimulating C. difficile toxin production.

Answer

Promoting the sporulation of C. difficile.

Answer

Enhancing the adherence of C. difficile to intestinal epithelial cells.

Question 3

A 45-year-old immunocompetent woman travels to a rural area with poor sanitation. Two weeks later, she develops sudden onset watery diarrhea, abdominal cramps, and vomiting. Stool culture is positive for motile, comma-shaped rods. Which of the following is the most appropriate initial management for this patient?

Accepted Answer

Aggressive oral rehydration therapy

Answer

Oral ciprofloxacin

Answer

Intravenous metronidazole

Answer

Oral loperamide

Question 4

Regarding the pathogenesis of infectious diseases, which of the following best defines 'virulence'?

Accepted Answer

The degree of pathogenicity of a microbe.

Answer

The ability of a pathogen to cause disease in a host.

Answer

The rate at which a pathogen spreads within a population.

Answer

The number of microorganisms required to cause infection.

Question 5

Which of the following is an example of horizontal gene transfer in bacteria that involves the transfer of genetic material via a bacteriophage?

Accepted Answer

Transduction

Answer

Conjugation

Answer

Transformation

Answer

Mutation

Question 6

A 70-year-old male with a history of COPD and chronic steroid use presents with fever, cough productive of purulent sputum, and dyspnea. Chest X-ray shows a right lower lobe infiltrate. Gram stain of the sputum reveals Gram-negative rods. Which of the following is the most likely pathogen, considering his risk factors?

Accepted Answer

Klebsiella pneumoniae

Answer

Haemophilus influenzae

Answer

Streptococcus pneumoniae

Answer

Mycoplasma pneumoniae