Staphylococcal Infections MCQ Quiz | Infectious Diseases – Bacterial

Welcome to this comprehensive quiz on Staphylococcal Infections, tailored for MBBS students. This quiz is designed to test your understanding of the microbiology, pathogenesis, clinical manifestations, diagnosis, and management of diseases caused by *Staphylococcus* species, a crucial topic in infectious diseases. You will encounter 25 multiple-choice questions covering key concepts from skin and soft tissue infections to life-threatening conditions like Toxic Shock Syndrome and endocarditis. After submitting your answers, you’ll receive your score and see the correct responses highlighted. For your future reference and revision, an option to download all the questions along with their correct answers in a PDF format is available at the end of the quiz. Good luck!

1. Which virulence factor of *Staphylococcus aureus* binds to the Fc portion of IgG, thereby inhibiting opsonization and phagocytosis?

2. A patient presents with high fever, hypotension, a diffuse erythematous rash, and multi-organ failure. This presentation is most strongly associated with which staphylococcal toxin?

3. The mechanism of methicillin resistance in MRSA is primarily due to:

4. A 25-year-old male with a history of intravenous drug use presents with fever, chills, and a new-onset heart murmur. Blood cultures grow Gram-positive cocci in clusters. The most likely causative organism for his infective endocarditis is:

5. Staphylococcal Scalded Skin Syndrome (SSSS) in newborns is caused by the systemic effects of which toxin?

6. Which of the following is a key laboratory test used to differentiate *Staphylococcus aureus* from coagulase-negative staphylococci (CoNS)?

7. A patient develops vomiting and diarrhea 2-4 hours after eating potato salad at a picnic. The symptoms resolve within 24 hours. This type of food poisoning is most likely caused by:

8. The *mecA* gene, responsible for methicillin resistance, is carried on which mobile genetic element?

9. Panton-Valentine Leukocidin (PVL), a cytotoxin often associated with community-acquired MRSA (CA-MRSA), primarily targets which cells?

10. What is the first-line treatment for a severe, systemic infection confirmed to be caused by Methicillin-Susceptible *Staphylococcus aureus* (MSSA)?

11. A patient with a prosthetic heart valve develops endocarditis 3 months post-surgery. The most common causative agent for this condition is:

12. Which of the following skin infections is characterized by superficial, honey-crusted lesions, commonly seen in children, and can be caused by *S. aureus*?

13. The catalase test is performed on a Gram-positive coccus isolate. The test is positive (bubbles produced). This result effectively rules out which of the following genera?

14. A young, sexually active female presents with a urinary tract infection. The urine culture grows a coagulase-negative *Staphylococcus* that is resistant to novobiocin. The most likely organism is:

15. The primary reservoir for *Staphylococcus aureus* in humans, from which most infections originate, is the:

16. Which of the following antibiotics is a glycopeptide, often used as the empirical treatment for suspected severe MRSA infections?

17. A carbuncle is best described as:

18. The “slide coagulase test” detects which specific virulence factor of *S. aureus*?

19. For a patient with a severe MRSA pneumonia, which antibiotic is sometimes preferred over vancomycin due to its better lung tissue penetration and inhibition of toxin production?

20. Which feature is characteristic of community-acquired MRSA (CA-MRSA) strains compared to hospital-acquired MRSA (HA-MRSA) strains?

21. A patient is diagnosed with osteomyelitis of the vertebra. Which organism is the most common cause of this condition?

22. The “D-test” is used in the laboratory to detect inducible resistance to which antibiotic in staphylococci that appear erythromycin-resistant and clindamycin-susceptible?

23. Bullous impetigo, characterized by large, flaccid bullae, is a localized form of Staphylococcal Scalded Skin Syndrome caused by the action of:

24. In treating bacteremia caused by MSSA, which of the following is considered inferior to beta-lactam therapy despite in-vitro susceptibility?

25. The ability of *Staphylococcus epidermidis* to cause infections related to catheters and prosthetic devices is primarily due to its ability to: