Lecture 12 Staphylococcus

GRAM POSITIVE COCCI
Family:
MICROCOCCACEAE
Genus:
Micrococcus
Genus:
Staphylococcus
GRAM POSITIVE COCCI
Staphylococcus
Streptococcus
CATALASE +
CATALASE -
Family:
STREPTOCOCCACEAE
Genus:
Streptococcus
Genus:
Enterococcus
Staphylococcus
Staphylococcus
Morphology: Gram + cocci, irregular clusters
•
S. aureus
Coagulase neg.
stapylococci
(S. epidermidis etc.)
Coagulase +
Coagulase -
β-hemolysis
- hemolysis
Several diseases
Opportunistic pathogen
Staphylococcus
Staphylococcus
Staphylococcus aureus
Staphylococcus aureus
COAGULASE +
CNS
CNS
COAGULASE -
1
Staphylococcus aureus
Culture: BA: golden yellow, β-hemolysis
Virulence factors:
protein A: binds IgG (Fc portion)
teichoic acids: adhesins
capsule
Enzymes:
Coagulase
Hyaluronidase
Staphylokinase (fibrinolysin)
DNAse, lipase
Toxins:
α, β, γ, δ toxin
Panton-Valentine
leukocidin (PVL)
Exfoliative toxin (scalded
skin syndrome)
Toxic shock syndrome
toxin
Enterotoxins (A-F) heat
resistance!
Memrane damage
Protease
Superantigens
Pathogenicity
Inflammatory/pyogenic:
• Impetigo
• folliculitis
• furunculus
• carbunculus
• Paronychia
•
•
•
•
Toxin mediated:
• Food poisoning
• Toxic shock
syndrome
• Scalded skin
syndrome
Osteomyelitis
Arthritis
Pneumonia
Sepsis
Impetigo
a) impetigo contagiosa
Streptococcus pyogenes
Impetigo
b) bullosus impetigo
Staphylococcus aureus
± Staphylococcus aureus
2
Folliculitis
Furunculus, carbunculus
Gram+:Staphylococcus aureus
Gram-: Enterobacteriaceae,
Pseudomonas
Paronychia
- Staphylococcus aureus
Cellulitis (phlegmone)
Ecthyma
- Staphylococcus aureus, Streptococcus pyogenes
- Pseudomonas aeruginosa
Toxic shock syndrome
Streptococcus pyogenes
Staphylococcus aureus
3
Scalded skin syndrome
Treatment
Staphylococcus aureus
•
•
•
•
•
(Penicillin)
Oxacillin
Erythromycin
Cephalosporins
Vancomycin (for MRSA: methicillin (oxacillin)resistant S. aureus)
Frequent multiresistance
Vancomycin resistant S. aureus
• VISA (vancomycin-intermediate S. aureus)
• hVISA (heterogenous vancomycinintermediate S. aureus)
• VRSA (high-level vancomycin-resistant S.
aureus)
• mechanism of VRSA:
change in the peptidoglycan peptide side chain
(D-alanine-D-alanine to D-alanine-D-lactate)
Epidemiology and prevention
• Source: skin, nose
• Transmission: hands, objects
• Prevention: cleanliness, hand disinfection
reduce colonisation in nose (antibiotics)
• Source of infection: phage typing
• Important iatrogenic (nosocomial) pathogens:
newborn nursery, intensive care units, operating rooms
4
Coagulase negative staphylococci
• S. epidermidis, S hemolyticus, S. hominis etc.
• normal flora of skin
• opportunistic pathogen - patients with prosthetic
appliances, prosthetic heart valve, permanent cathether
• S. saprophyticus
• pathogen in urinary tract
5