Clostridium botulinum
The main virulence factor is botulinum toxin.
The botulinum toxin is synthesized as a single polypeptide and released in the blood circulation which is less efficacious. The chain is chopped into two pieces large and small chain joined together by disulphide bond. The function of heavy chain is o regulate the binding to the presynaptic receptor and make passage for light chain. the light chain enters into the neuron and digests synaptobrevin II present in synaptic vesicle and inhibits the release of acetylcholine. Ultimately it affects the neuronal transmission of signal and causes paralysis.

Clostridium perfringens type A
The main virulence factor is alpha toxic (phospholipase C). Other virulence factors are kappa toxin (collagenase), eta toxin (lethal effect), theta toxin (hemolysin), mu toxin (hyaluronidase). These toxin leads to gas gangrene, wound infection, septicemia and food poisoning. It lacks beta toxin, epsilon toxin, tau toxin, lambda toxin, delta toxin.
The alpha-toxin and kappa toxin mainly hydrolyzes phospholipids from the plasma membrane and collagen from the extracellular matrix, which is essential component for the integrity of the membrane and body structure. Other toxins act on the vascular endothelium and affect the permeability of blood capillary in the brain.

Clostridium perfringens type C
The main virulence factor is alpha toxic (phospholipase C), beta toxin (lethal and necrotizing properties), theta toxin (hemolysin) and kappa toxin (collagenase). Other virulence factors are nu toxin (deoxyribonuclease). These toxin leads to enteritis in animals and enteritis necroticans in human.
The alpha-toxin and beta toxin are produced in the intestine and lead to mucosal necrosis and this damages mucosal cells and linings.

Staphylococcus spp. (S.aureus)
S. aureus produces many virulence factors such as cell-associated polymers (peptidoglycans, teichoic acid, capsular polysaccharides), cell surface proteins (protein A, clumping factors), extracellular enzymes (coagulase, hyaluronidase, nuclease, receptors for many mammalian proteins such as fibronectins, fibrinogens, IgG), toxins (hemolysins, leucocidins, enterotoxins, exfoliative toxin) etc.

The Bacteroides genus is an important member of the gut microbiota....