Antimicrobials, NEET PG & INI-CET Pharmacology MCQs

Explanation

Isoniazid increases pyridoxine excretion, causing a deficiency neuropathy. Prophylactic pyridoxine prevents it, particularly in those at risk such as diabetics, people with alcohol dependence and pregnant women.

Explanation

Aminoglycosides accumulate in renal proximal tubule cells (nephrotoxicity, usually reversible) and in cochlear and vestibular hair cells (ototoxicity, often permanent). Once-daily dosing and level monitoring reduce the risk.

Explanation

Ethambutol causes dose-dependent retrobulbar (optic) neuritis with reduced acuity and red-green colour blindness. It is usually reversible on stopping the drug; visual acuity and colour vision should be checked before and during treatment.

Explanation

Rifampicin colours urine, sweat and tears orange-red, which is harmless but alarming if unwarned. It is also a potent CYP450 inducer, reducing the effect of oral contraceptives, warfarin and many other drugs.

Explanation

Vancomycin is first-line for serious MRSA infections, with linezolid and daptomycin as alternatives. It can cause red man syndrome with rapid infusion and is nephrotoxic at high trough levels.

Explanation

Fluoroquinolones are associated with tendinitis and tendon rupture, and cause cartilage damage in animal studies, so they are avoided in children and pregnancy. They can also prolong the QT interval.

Explanation

Amphotericin B binds ergosterol in the fungal cell membrane, forming pores that cause leakage of ions and cell death. Azoles instead inhibit ergosterol synthesis and echinocandins block beta-glucan synthesis. Amphotericin is notably nephrotoxic.

Explanation

Beta-lactams bind penicillin-binding proteins and inhibit transpeptidation, the cross-linking step of peptidoglycan cell wall synthesis, leading to bacterial lysis. Resistance often occurs through beta-lactamase enzymes.