Staphylococcus - Microbiology - Lecture Slides, Slides of Microbiology

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Staphylococcus

Classification

• Family
• Genus
• Species

Micrococcaceae

Micrococcus and Staphylococcus

S. aureus S. saprophyticus S. epidermidis more M. luteus than 20 specie s Docsity.com

Cell-Associated Virulence Factors

• Capsule or slime layer (glycocalyx)
• Peptidoglycan (PG)
• Teichoic acid is covalently linked to PG and

is species specific:

• S. aureus ribitol teichoic acid

(polysaccharide A)

• S. epidermidis glycerol teichoic acid

(polysaccharide B)

• Protein A is covalently linked to PG
• Clumping factor (bound coagulase)

Virulence Factors

Extracellular Enzymes

• Coagulases (bound or free)
  • Antigenic
• Hyaluronidase
  • “spreading factor” of S. aureus
• Nuclease
  • Cleaves DNA and RNA in S. aureus
• Protease
  • Staphylokinase (fibrinolysin)
• Lipases
• Esterases Docsity.com

• Enterotoxin
• Exfoliative toxin (epidermolytic toxin)
• Pyrogenic exotoxins

Virulence Factors: Exotoxins

Pathogenesis

• Pass skin – first line of defense
  • Benign infection
    • Phagocytosis
    • Antibody
    • Inflammatory response
  • Chronic infections
    • Delayed hypersensitivity

Clinical Manifestations/Disease

• Other infections
  • Primary staphylococcal pneumonia
  • Food poisoning vs. foodborne disease
  • Toxic shock syndrome

Metastatic Infections

• Pulmonary and cardiovascular

infection

• Bacteremia
• Osteomyelitis

disease of growing bone

Staphylococcal Lab ID & Diagnostic Tests

• Microscopic
  • Lab isolation
  • Coagulase positive

 S. aureus

Treatment

• Drain infected area
• Deep/metastatic infections
  • semi-synthetic penicllins
  • cephalosporins
  • erythromycin
  • clindamycin
• Endocarditis
  • semi-synthetic penicillin + an aminoglycoside