Staph. virulence factors Flashcards
Peptidoglycan
More thicker, Confers cell rigidity and induces inflammatory response
Teichoic acid
Helps in adhesion to mucosa’ surfaces and prevent opsonisation
Clumping factor/ Bound coagulase
Responsible for slide coagulase reaction
Protein A
Antiphagocytic, anticomplernentary, chemotactic Binds to Fc region of lgG leaving Fab region free to bind to an Antigen - Basis of Coagglutination reaction
a Hemolysin
Inactivated at 70 °C; reactivated paradoxically at 100 00 (due to denaturation of a heat labile inactivator at 100 °C) Leucocidal, Cytotoxic, dermonecrotic, lethal
b Hemolysin
Activity Sphingomyelinase Lyses sheep RBC, but not human or rabbit RBC Exhibits hot:cold phenomenon
y Hemolysin
Bicomponent protein, Lyses rabbit sheep and human RBCs
6 Hemolysin
Detergent like, Lyses rabbit, sheep and human RBCs
Leucocidins/ Two components F and S Panton valentine (PV)
Damage PMN and macrophages toxins Associated with Community acquired MRSA SynergoAmenotropic toxins: Bicomponent toxins such as y and PV toxin act synergistically and are called as Synergohymenotropic toxins
Epidermolytic toxin (Exfoliative toxin)
Mainly belong to phage group II Scalded skin syndrome (Nikolsky’s sign-epidermal layer separated) Severe- Ritter disease (newborn), toxic epidermal necrolysis (TEN) (adult) Milder- Pemphigus neonatorum, bullous impekgo
Enterotoxins
Produced by 50% of clinical isolates Cause food poisoning Incubatory Period: 1-6 hr due to preformed toxin Site of action: The toxin stimulates:the vagus nerve and vomitilgcenter of the brain. It also stimulates the intestinal peristaltic activity. Heat stable (not destroyed after heating food) Most common food items involved are milk products, bakery food, custards, potato salad, or processed meats. Multiple antigenic type (A-E, G-1, R-T and V) (MC- type A) -
Toxic shock syndrome toxin
Most strains belong to phage group I Enterotoxins F (pyrogenic exotoxin C) is the most common TSST, followed by Enterotoxin B,C Risk factor: Use of vaginal tampon by menstruating females (however, males and nonmenstruating females also get effected rarely) Anti TSST1 Antibody is protective Manifestations: Rash, fever, hypotension and Multi organ failure Diagnosis: Detection of TSST by latex agglutination test and enzyme immunoassay. Detection of TSST genes 1 and 2 by PCR Treatment: Clindamycin (reduces toxin synthesis)
Extracellular enzymes
Specific to S.aureus: Coagulase, heat stable thermonuclease, DNase, phosphatase • Present in most staphylococci: Protease. lipase, staphylokinase (fibrinolysin), hyaluronidase
