Staphylococcal Infections MCQ Quiz | Wounds & Anaerobes

1. Which biochemical test is most crucial for differentiating Staphylococcus aureus from other staphylococcal species like S. epidermidis?

2. The mecA gene in Methicillin-resistant Staphylococcus aureus (MRSA) confers resistance by encoding which altered protein?

3. A patient presents with fever, hypotension, a diffuse erythematous rash, and multi-organ failure. This presentation is characteristic of Toxic Shock Syndrome (TSS), caused by which staphylococcal exotoxin?

4. The virulence factor Protein A in S. aureus helps the bacterium evade the host immune system by:

5. A young child presents with large, flaccid bullae and subsequent exfoliation of the skin, resembling a burn (Ritter’s disease). This condition, known as Staphylococcal Scalded Skin Syndrome (SSSS), is caused by:

6. A group of people develop severe nausea, vomiting, and diarrhea 2-4 hours after eating at a picnic. The potato salad is implicated. What is the most likely pathogenic mechanism?

7. Which of the following is the most common causative agent of osteomyelitis in children and adults?

8. A patient with an indwelling central venous catheter develops a fever and signs of sepsis. Blood cultures grow a coagulase-negative Staphylococcus. Which species is most likely responsible?

9. The key pathogenic mechanism for device-related infections caused by S. epidermidis is its ability to:

10. For a severe, hospital-acquired MRSA bacteremia, what is the standard first-line intravenous antibiotic therapy?

11. A young, sexually active female presents with symptoms of a urinary tract infection. A urine culture grows a Gram-positive, coagulase-negative, novobiocin-resistant coccus. The most likely organism is:

12. Panton-Valentine Leukocidin (PVL) is a cytotoxin strongly associated with which type of S. aureus infection?

13. Which of the following describes the appearance of S. aureus on Mannitol Salt Agar (MSA)?

14. An IV drug user presents with high fever, chills, and a new heart murmur. Echocardiogram reveals vegetations on the tricuspid valve. What is the most probable causative organism?

15. A superficial skin infection characterized by vesicles that rupture to form a thick, adherent, honey-colored crust is known as:

16. Which of the following antibiotics is a glycopeptide that inhibits cell wall synthesis and is reserved for treating severe MRSA infections?

17. A carbuncle is best described as:

18. The “slide coagulase test” detects which factor produced by S. aureus?

19. Which of the following is NOT a typical feature of a community-acquired MRSA (CA-MRSA) strain compared to a hospital-acquired MRSA (HA-MRSA) strain?

20. What is the primary reason for performing incision and drainage (I&D) on a staphylococcal abscess?

21. In a patient with a confirmed Methicillin-Sensitive S. aureus (MSSA) bloodstream infection, which antibiotic is considered the drug of choice for definitive therapy?

22. Which of the following Staphylococcal species is coagulase-positive but can be differentiated from S. aureus, often being associated with more aggressive endocarditis?

23. The “D-test” is performed to detect inducible resistance to which antibiotic in staphylococci that appear erythromycin-resistant and clindamycin-sensitive?

24. A patient with a prosthetic hip joint develops a late-onset infection (>12 months post-op). What is the most common etiology?

25. On Gram stain, staphylococci typically appear as: