Gram Positive Cocci
-
Upload
nisha-anggia -
Category
Documents
-
view
1 -
download
0
description
Transcript of Gram Positive Cocci
GRAM POSITIVE COCCI
•Gram positive and negative bacteria: The cell wall very different:
. Peptidoglycanvery strong,thick and rigid.. Teichoic acid surface
antigen.
Species cause of human disease:
• Staphylococcus aureus• Streptococcus pneumoniae• Streptococcus pyogenic• ect
Structure and function
• Capsule antiphagocytosis• Peptidoglycan stimulate production of
endogenous pyrogens• Protein spesific:A,M,F
antiphagocytosis,anticomplementary• Teichoic acid attachment to mucosal
Pathogenesis and Immunity
The virulence is determined by:a variety of structural molecule and elaborated toxins and enzymes. virulence factors
• Toxins- Exotoxin : 1. Cytotoxin
2. Enterotoxin food poisoning.resistant to gastric &jejunal enzymes..heat stable.stimulate intestinal
peristalsis
• Enzymes. Coagulase fibrin layer. Catalase H2O2. Hyaluronidase spreading factors. Lipase . Fibrinolysin. Penicillinase. Ig A protease. Hemolysin : Streptolysin O antigenic
Important features of pathogenesis
• Staphylococcus aureus1. Pyogenic (abscess)
- local skin infection surgical wound infection
- disseminated sepsis2. Toxigenic food poisoning
• Staphylococcus epidermidisPyogenic iv catheter sites & prostetic
devices• Staphylococcus saprophyticus
Pyogenic UTI(Urinary Tract Infection )
• Streptococcus pyogenes1.Pyogenic
. Local : skin,pharing
. Disseminated : sepsis2. Toxigenic3. Immune-mediated(post Streptococcal infection,non suppurative)
Poststreptococcal diseaseImmunologic response to streptococcal M
protein that cross-react with human tissues.1.Acute Glomerulonephritis
antigen-antibody complexes on glomerular.1.Acute Rheumatic Fever
autoimmune disease
• Streptococcus pneumoniaePyogenic : . Pneumonia
. Otitis media . Meningitis