STAPHYLOCOCCAL INFECTIONS- S.aureus: aerobic, gram-positive catalase-positive bacteria arranged in clusters
- Best defense: intact skin
- MRSA: ↑ resistance to methicillin caused by staphylococcal chromosome cassettemec (SCC mec), specifically mecAgene (encodes alternative penicillin-binding protein, PBP2a)
- Select S.aureus toxins:
| | | | | | | | Toxic shock syndrome toxin-1 (TSST-1) | | Superantigen, involved in toxic shock syndrome (TSS) | | | Exfoliative toxin (ET-A, ET-B) | | Protease activity, splits epidermal desmoglein 1, involved in staphylococcal scalded skin syndrome (SSSS) and bullous impetigo | | | Panton–Valentine leukocidin (PVL) | | In many community-acquired MRSA strains, associated with ↑ virulence (leukocyte destruction, necrosis) |
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| | Figure 4.7
A: Impetigo
(Courtesy of Dr. Paul Getz)
B: Bullous impetigo, arm
C: SSSS
(Reprint from Allen HB.
Dermatology Terminology.
New York, NY: Springer; 2010) |
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