1. Introduction

Most common pyogenic bacteria
Can cause abscesses, food poisoning, urinary tract infections (UTIs), toxic shock and scalded skin, osteomyelitis, and endocarditis
Resistant to heat, dessication, and high salt concentrations
S. epidermidis found on skin of most people, but not usually pathogenic
S. aureus primarily responsible for infections

2. Identification

S. aureus can produce numerous syndromes
1. Abscess or boil formation can lead to cellulitis or impetigo
2. If bone is affected produces osteomyelitis affecting heart and brain
3. Scalded Skin Syndrome (SSS) life-threatening
4. Toxic Shock Syndrome (TSS) produces fever, rash, and hypotension
S. epidermidis can cause endocarditis in prosthetic heart valve or septicemia in indwelling medical device
S. saprophyticus responsible for UTIs

S. aureus
1. Capsule: anti-phagocytic if present
2. Peptidoglycan: activates alternative complement pathway
3. Teichoic acid: complement activation and pro-inflammatory
4. Protein A: inhibits IgG
5. Catalase: prevents neutrophils from killing bacteria
6. Coagulase: promotes clot formation inhibiting WBC activity
7. Staphylokinase: activates plasminogen
8. Alpha toxin: creates channels in cell membranes causing hemolysis
9. Hyaluronidase: hydrolyzes connective tissue and facilitates spread
10. Virulence enhancers: lipases, proteases, DNases
S. epidermidis
1. Exopolysaccharide slime layer: sticks to surfaces
2. Fimbriae: help bacteria stick to surfaces

Drain abscesses to prevent spread
Many staphylococci resistant to penicillins, semisynthetic penicillins, and cephalo- sporins
Treat with vancomycin or gentamycin