Antibiotics and Immunity

Aspirin is primarily used as an analgesic (pain reliever) and antipyretic (fever reducer), not as an antibiotic, antiseptic, or antimalarial.

Chloramphenicol is a broad-spectrum antibiotic effective against Salmonella typhi, the bacteria that causes typhoid fever, though its use is now restricted due to serious side effects like aplastic anemia.

Auromycin (chlortetracycline) is a tetracycline-class antibiotic effective against both Gram-positive and Gram-negative bacteria, making it broad-spectrum. Penicillin G and Benzyl penicillin are narrow-spectrum, primarily effective against Gram-positive bacteria. Salicylamide is not an antibiotic but a non-steroidal anti-inflammatory drug derivative.

This option is correct because Hektoen Enteric Agar is a selective and differential agar for the isolation and cultivation of the gram-negative enteric microorganisms, especially Salmonella and Shigella. MacConkey Agar is a selective and differential medium designed to isolate and differentiate enterics based on their ability to ferment lactose.

Alcaligenes faecalis, Enterobacter aerogenes and Klebsiella pneumoniae: All are Gram-negative bacteria.

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.

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.

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.

Isoniazid acts by blocking pyridoxine and nicotinamide catalyzed reactions. It is a structural analog of pyridoxine and nicotinamide and thus, can block pyridoxine and nicotinamide catalyzed reactions.

Anthramycin is an anti-tumor antibiotic. It works by inhibiting the synthesis of RNA and DNA of carcinoma cells.

Bacterial cells susceptible to penicillin can be protected from destruction if the medium in which they are exposed is of high osmotic pressure. The high osmotic pressure prevents the cells from bursting.

Erythromycin manifests its action by binding to 23S rRNA component of 50S subunit of the ribosome, thereby blocking the tunnel where the polypeptide string is supposed to exist.

Fosfomycin inhibits conversion of UDP-GlcNAc to UDP-MurNAc. This is the first committed step in peptidoglycan biosynthesis, so amenable to selective action.

Lincomycin belongs to lincosamide group of antibiotics. Lincomycin is an antibiotic that fights bacteria.

Quinolones bind to DNA gyrase as a topoisomerase inhibitor, thereby inhibiting synthesis of DNA.