Antibiotics and Immunity

Chloramphenicol is not effective against Pseudomonas aeruginosa. Chloramphenicol resistance may be carried on a plasmid that also codes for resistance to other drugs or it is effectively pumped out by efflux pumps.

This is the correct answer. Mupirocin reversibly binds to the isoleucyl t-RNA synthetase in Staphylococcus aureus and Streptococcus, resulting in inhibition of protein synthesis.

Fourth generation cephalosporins covers Pseudomonas infection.

Whooping cough is caused by a Gram-negative, aerobic, pathogenic and encapsulated coccobacillus of the genus Bordetella called Bordetella pertussis. It affects the respiratory tract. Erythromycin is likely to treat whooping cough as it is effective on aerobic respiratory pathogens.

This statement is false. Both drugs are bacteriostatic, when used alone, but the combination shows bactericidal activity.

Trimethoprim has a very high affinity for bacterial dihydrofolate reductase. It competitively inhibits the activity of DHFR and inhibits the reduction of dihydrofolic acid (DHF) to tetrahydrofolic acid (THF). THF is an essential precursor in the thymidine synthesis pathway and interference with this pathway inhibits bacterial DNA synthesis.

Pristinamycin belongs to the streptogramin family. It is used to treat VRE (vancomycin resistant enterococci) infections. It is effective against VRE because it inhibits protein synthesis and vancomycin acts on the cell wall. Thus, its mechanism of action is altogether different than vancomycin. It also enters the bacterial cell easily, whereas other protein inhibitors fail to do so.

Daptomycin is active against all Gram-positive organisms. They include glycopeptide resistant enterococci (GRE), Staphylococci (including methicillin resistant Staphylococcus aureus), Streptococci, corynebacteria and stationary-phase Borrelia burgdorferi persisters.

Radezolid inhibits the initiation step of protein synthesis. It targets an early step involving the binding of N-formylmethionyl-tRNA to the ribosome.

Lantibiotics are similar to bacteriocins. In fact, the lantibiotics are a class of more extensively modified bacteriocins, also called Class I bacteriocins (toxins produced by bacteria).

Ceftolozane/tazobactam combination was marketed in 2015. The combination has activity against many Gram-positive and is resistant to Gram-negative pathogens and Pseudomonas aeruginosa. Thus, ceftolozane and tazobactam combination antibiotic is the latest antibiotic in the market.

This is the correct match. Polymyxin B alters bacterial outer membrane permeability by binding to a negatively charged site in the lipopolysaccharide layer and destabilises the outer membrane. Enoxacin functions by inhibiting bacterial DNA gyrase and topoisomerase IV and prevents bacterial DNA replication, transcription, repair and recombination. Furazolidone works by crosslinking of DNA. Daptomycin disrupts multiple aspects of bacterial cell membrane function which results in bacterial cell death.

Common cold is a viral disease and cannot be treated using antibiotics.

A bacterium with an outer membrane is gram negative and protected against certain antibiotics such as penicillin.

Viruses replicate inside host cells using the host's own machinery, making it extremely difficult to develop drugs that target the virus without harming human cells. Bacteria, fungi, and protozoa have their own cellular structures and metabolic pathways that can be selectively targeted with fewer side effects.