Virulence factors of s. aureu Stage iv, continued Secretion of to×ins Exfoliative toxin(scalded skin syndrome) extrachromosomal Toxic Shock Syndrome toxin-1(enterotoxin F)- exotoxin secreted during growth Some produce enterotoxin B instead(role not clear) BIOL 533 17 Lecture 10
BIOL 533 17 Lecture 10 Virulence Factors of S. aureus • Stage IV, continued – Secretion of toxins • Exfoliative toxin (scalded skin syndrome)— extrachromosomal • Toxic Shock Syndrome toxin-1 (enterotoxin F)— exotoxin secreted during growth – Some produce enterotoxin B instead (role not clear)
Virulence factors of s. aureu Stage iv, continued Secretion of toxins Enterotoxins(A-E)-found in both S aureus and Sepidermic Resistant to hydrolysis by gastric and jejunal enzymes Stable to heating at 100 C for 30 minutes Mechanism of toxin activity not understood; no satisfactory animal model > Stimulate intestinal peristalsis and have CNs effect; intense vomiting BIOL 533 18 Lecture 10
BIOL 533 18 Lecture 10 Virulence Factors of S. aureus • Stage IV, continued – Secretion of toxins • Enterotoxins (A-E)—found in both S. aureus and S. epidermidis – Resistant to hydrolysis by gastric and jejunal enzymes – Stable to heating at 100°C for 30 minutes – Mechanism of toxin activity not understood; no satisfactory animal model » Stimulate intestinal peristalsis and have CNS effect; intense vomiting
Pathogenesis of s aureus Treatment Antibiotics Types Methicillin, oxacillin nafcillin and dicloxacillin (semisynthetic penicillins resistant to B-lactam hydrolysis) Majority of patients can be treated but 10-15% S,aureus and 40% coagulase-negative staphylococci are resistant treat with vancomycin BIOL 533 Lecture 10
BIOL 533 19 Lecture 10 Pathogenesis of S. aureus • Treatment – Antibiotics • Types: – Methicillin, oxacillin, nafcillin, and dicloxacillin (semisynthetic penicillins resistant to ß-lactam hydrolysis) – Majority of patients can be treated, but 10-15% S. aureus and 40% coagulase-negative staphylococci are resistant; treat with vancomycin
Pathogenesis of s aureus Treatment Antibiotics Resistance: Plasmid-borne(hydrolysis of B-lactam ring) Chromosomal-change in structure of penicillin-binding proteins BIOL 533 20 Lecture 10
BIOL 533 20 Lecture 10 Pathogenesis of S. aureus • Treatment – Antibiotics • Resistance: – Plasmid-borne (hydrolysis of ß-lactam ring) – Chromosomal—change in structure of penicillin-binding proteins
Streptococci Fermentative(oxygen tolerant) Gram cocci in chains Sensitive to penicillins Human reservoir-passed from person to person BIOL 533 Lecture 10
BIOL 533 21 Lecture 10 Streptococci • Fermentative (oxygen tolerant) Gram+ cocci in chains • Sensitive to penicillins • Human reservoir—passed from person to person