Question

The 3 bacteria below each has different virulence factors/ mechanisms that allow them to counter the immune system. Briefly describe each case.

(1) Stahylococcus aureus

(2) Listeria monocytogenes

(3) Neisseria meningitidis

Answer 1

1 . Staphylococcus aureus:-it is a gram positive bacteria. It cause boils, abscesses, multiorgan failure.It has many virulence factor by which it can cause infection in the host :-

(a) Enzymes:- s. aureus produce coagulase, that clots blood plasma and helps bacteria to avoid Phagocytosis. Hyaluronidase, and lipase enzymes act as spreding factor for S. aureus in the host.

(b) Toxin:- TSST-1 an enterotoxin produce by S. aureus act as superantigen and cause spetic shock.

2.L.monocytogenes:-a gram positive facultatively anaerobic bacteria cause foodborne listlisteriosis. It also have interesting capability to survive in the host:-

(a)avoid the macrophage and spread from one cell to another by actin polymerization process.

(b)produce Listeriolysin o and phopholipase A, this factor helps to invade the hots tissue.

3.Neisseria meningitidis:- a gram negative bacteria. It cause infection by using following strategies/molecule

a) N. meningitidis posses a capsule that helps to inhibit Phagocytosis

b) Produce Lipooligosaccharide(LOS) endotoxin that lysis RBC

c) produce IgA potease, that cleave antibody, and thus enzymes helps to spread rapidly.