Pathogenicity of Microorganisms (GATE)

Gnotobiotic animals require vitamin B in higher amounts than normal animals. They are free of microbes which can synthesise vitamin B. Thus, they require more vitamin B as compared to normal animals.

Comedones are associated with Propionibacterium acne. This bacterium causes acne vulgaris. In the first stage of the disease, comedones are formed where distension of the glands is caused by an accumulation of sebum, hair and bacteria.

Bacteroides melaninogenicus colonises the oxygen-deficient gingival crevices during puberty.

The intestinal microflora of the young breast fed infants consists mainly of Bifidobacteria, which are Gram-positive. The low pH in the large intestine of the breast fed babies would be unfavorable for the growth of E. coli, and so Bifidobacteria proliferate.

The surface of influenza virus particles is studded with hemagglutinin spikes. It can cause attachment of the virus to specific mucoprotein receptors on the surface of host cells.

Streptococcus pyogenes attaches specifically to the epithelial cells of the throat by means of cell wall proteins called M-proteins.

Clostridium perfringens present in the soil or fecal matter enters directly in the body through breaches. They may enter through wounds. Thus, they are passive penetrators.

Vibrio cholerae does not penetrate epithelial surface. It causes damage without penetration in the body. It multiplies on the epithelial surface and produces a toxin that causes loss of fluid from the epithelial cells and kills cells.

The capsule of Bacillus anthracis is composed of a polypeptide, not a polysaccharide.

Active multiplication of bacteria in the blood with the production of toxins is called septicemia.

Streptococcus pyogenes secretes a toxin that acts as cardiotoxin (SLO) in rabbits. It disrupts the cardiac pumping in rabbits. This toxin acts as leukocidin in humans, destroying the leukocyte.

Mycoplasma secretes hydrogen peroxide and ammonia as virulence factor. These compounds accumulate locally to high concentrations, thereby damaging epithelial cells.

Ureoplasma does not secrete DNAase. Hydrogen peroxide and ammonia are excreted as virulence factor.

This is the correct match.
Diphtheria toxin kills several kinds of cells and is termed cytotoxin.
Tetanus toxin affects nerve tissues and is called neurotoxin.
The toxin made by V. cholerae in the intestine is termed enterotoxin.
The toxin secreted by V. parahemolyticus is a cardiotoxin.

This is the correct match.
Tetanus toxin acts on the central nervous system to prevent the release of inhibitory factor.
In botulism, the toxin binds to the axon near the neuromuscular junction and prevents the secretion of acetylcholine.
Cholera toxin hampers the activity of the enzyme adenylate cyclase in the cell.
Diphtheria toxin inactivates elongation factor 2.