Phage typing is used to sub-type Staphylococcus aureus isolates for epidemiological investigation of hospital outbreaks. Group I phages lyse strains associated with which clinical syndrome that is NOT bullous impetigo?
- A Staphylococcal scalded skin syndrome (SSSS) — caused by Group II phage type 71 or 55 strains producing exfoliative toxins ✓
- B Staphylococcal toxic shock syndrome — caused by Group III strains producing TSST-1
- C Food poisoning — caused by Group IV phage types producing heat-stable enterotoxins A and D
- D Bacteremic infective endocarditis — caused by Group V phage types with MRSA carrying PVL
Explanation
In the International Phage Typing set for S. aureus, Group II phage types (notably phage type 71 and 3A/3B/3C/55/71 group) lyse strains that are responsible for staphylococcal scalded skin syndrome (Ritter's disease) and bullous impetigo, because these strains produce exfoliative toxins (ET-A and ET-B) which cleave desmoglein-1 in the superficial epidermis. Group III phage types include TSST-1-producing strains associated with toxic shock syndrome. Group I phages include strains linked to superficial skin infections and septicemia. The question tests understanding that SSSS is a Group II phage type association, not Group I.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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