Staphylococci

Gram (+)ve cocci;

Catalase (+)ve = ability to decompose hydrogen peroxide

If also coagulase (+)ve => S. aureus

Two coagulase (-)ve Staphs;

NOvobiocin - Saprophyticus is Resistant; Epidermidis is Sensitive (NO StRESs)

Staph. aureus

Catalase +, coagulase +,

also beta-hemolytic

ferment Mannitol

produce Yellow pigment (hence named aureus = gold)

Staph. aureus produces different hemolysins:

alpha-toxin --> hemolysis

beta-toxin --> sphingomyelinase

Proteins A, B, and C of gamma-toxin --> A+B = hemolysin, B+C = leukocidin

Panton-Valentine Leukocidin (PVL) which is commonly seen in community associated MRSA, is one of the pore-forming toxins (protein cytotoxin)

MRSA

Acute aggressive endocarditis in normal valves; IVDU (commonly involve Tricuspid valve)

most common cause of osteomyelitis

TSST-1