Staphylococcus

Hugh B. Fackrell

Filename: staph.ppt

Outline

• Definition

• Extracellular products

• Diseases
  • suppuration
  • intoxications

Staphylococcus

• Gram +ve cocci in clusters

• catalase +ve facultative anaerobes

• sensitive to lysostaphin endopeptidase

• resistant to lysozyme

• ribitol or glyercol teichoic acids

Staphylococcus: structure

• Gram positive spheres in grape-like clusters

• Staphylo= grapes

• Coccus = spheres

Extracellular Products of Staphylococci

TOXINS

• Hemolysins

• Leucocidin ( Leukocidin)

• Enterotoxins

• Exfoliative toxins

• TSS toxin

ENZYMES

• DNAse

• Coagulase

• Fibrinolysin

• Lipases

• Hyaluronidase

Staphylococcus aureus produces the enzyme Endonuclease

Staphlylococcal Coagulase

• Coagulase: enzymes that cause clotting of blood plasma

• Measured by
  • tube test (Free coagulase)
  • slide test (Bound coagulase)

• Differentiation of Staphylococcal pathogens
  • S.aureus coagulase positive

Coagulase vs FibrinolysinCompeting Enzymes

• Coagulase: forms clots

• Fibrinolysin: dissolves clots

• Staphylococcus produces coagulase early
  • protection against phagocytosis

• When cell numbers high make fibrolysin
  • break out of protection

Resistant to bile salts

• Most strains grow in the presence of 40% bile salts
  • colonize intestine

• Most strains grown the presence of 15% NaCl
  • Colonize the skin

Major Staphylococcal Pathogens

• Staphylococcus aureus
  • infections & intoxications

• Staphylococcus epidermidis
  • “stitch abcesses”

• Staphylococcus saprophyticus
  • urinary tract infections

Staphylococci are NOT highly invasive

• S aureus:50% are carriers
  • found in nose area

• S. epidermidis: universal
  • present on skin

• 95% have immunity to Staphylococci

Predisposing factors

• Break in the skin
  • operations, burns, abrasions
  • blockage of sweat glands

• Chronic diseases
  • cancer, diabetes, cirrhosis
  • Staphylococcal pneumonia

Staphylococcal diseases

• Suppurative Diseases
  • pus
  • infiltration of WBC of polymorphonuclear leucocytes

• Toxic poisonings

Staphylococcal Suppurative Diseases

• boils, furuncles, carbuncles

• wound infections

• deep tissue abcesses

• osteomyelitis

• pneumonia, empyema
  • (intrapleural abcesses)

• endocarditis, pericarditis

• meningitis

• purulent arthritis

Staphylococcal mastitis

• Udder infections in dairy cattle

• Penicillin resistant Staphylococci

• Before antibiotics
  • Streptococcus group B & Group C

Deep Tissue Abcesses

• Often resist antibiotics

• Surgical intervention

• Drainage

• Antitoxins

Staphylococcal Intoxications

• Enterotoxin
  • food poisoning

• Toxic shock syndrome

• Hemolysins

• Epidermolytic toxin
  • “scalded skin syndrome”

• Leucocidin

Staphylococcal Hemolysins

• Discovered because they Destroy RBCs

• 4 types
  • alpha: lethal cardiovascular
  • beta: “ hot cold” sphingomyelinase
    • aggregates platelets
  • gamma: slightly dermonecrotic
    • lethal in rabbits
  • delta: bee venom

PPT Slide

Platelet Damage by Toxins

PPT Slide

Staphylococcal Food Poisoning

• Secreted protein
  • produced at room temp
  • produced aerobically and anaerobically

• milk & meat products excellent media

• Food handlers - carriers

Staphlylococcal Food Poisoning Signs & Symptoms

• Symptoms
  • Nausea
  • Abdominal pain
  • Projectile vomiting
  • Diarrhea

• Onset: average 3 hours
  • 1-6 hours

• Duration: 24 hours

Enterotoxin

• Several different forms

• Protein 24,000 MW

• Resistant to
  • acids
  • proteases in digestive tract
  • boiling for 2 hours

• Gene carried by lysogenic phage

Toxic Shock Syndrome

• First reported 1980

• young women during menstruation

• tampons containing methacrylate supported growth of S. aureus and production of toxin

• Shock & death

The End