Staphylococcus spp.

MICROBIOLOGY

• Staphylococci (Staph): clustered gram-positive beta-hemolytic bacteria. S. aureus (SA) is coagulase positive.
• Coagulase-negative Staph (CoNS): >30 species, 15 of which are human pathogens. S. epidermidis, S. saprophyticus (novobiocin resistant), S. haemolyticus, S. lugdunensis, & S. schleiferi are most commonly isolated.
• SA produces several toxins, including enterotoxins, epidermolytic toxins, & toxic shock syndrome toxins (TSST)
• Staph grow rapidly on blood agar and other non-selective media. They can survive harsh environmental conditions, high salt media, & are relatively heat-resistant.
• Methicillin resistance: >80% of CoNS, and an increasing number of both hospital acquired & community acquired SA (MRSA) encompasses all B-lactam antibiotics, including cephalosporins. Vancomycin-intermediate resistance (VISA) and vancomycin-resistant strains have emerged.