gram positive cocci erly gram positive and negative bacteria: the cell wall very different:....

GRAM POSITIVE COCCIerly

•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

peristaltic

• 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.2. Acute Rheumatic Fever

autoimmune disease

• Streptococcus pneumoniaePyogenic : . Pneumonia

. Otitis media . Meningitis