Antimicrobials

Antimicrobials are agents that kill microorganisms or inhibit their growth. They include antibacterial, antiviral, antifungal, and antiparasitic drugs and may be natural, semisynthetic, or fully synthetic. They are used to prevent and treat infections in humans and animals and, in some contexts, in agriculture.

Bacteria-focused antimicrobials (antibiotics) have diverse mechanisms: some disrupt cell walls or membranes (for example beta-lactams such as penicillins and cephalosporins), others inhibit protein synthesis (macrolides, tetracyclines, aminoglycosides), and others interfere with nucleic acid synthesis (quinolones). Antivirals inhibit steps in viral replication or entry. Antifungals often target ergosterol in membranes or fungal cell wall synthesis. Antiparasitic drugs act on parasites through various pathways. Drugs may be broad-spectrum or narrow-spectrum, reflecting the range of organisms they affect.

Resistance occurs when microorganisms adapt to evade antimicrobial action. Mechanisms include enzymatic drug inactivation, target modification, efflux pumps, and biofilm protection. Misuse and overuse drive resistance, leading to treatment failures and accelerated spread. Antimicrobial stewardship emphasizes appropriate selection, dosing, route, and duration, along with surveillance and infection control.

Pharmacokinetics and administration vary by compound and indication. Drugs may be given orally, intravenously, or by other routes, with differing bioavailability, tissue penetration, and half-lives. Some agents require monitoring for toxicity or drug interactions.

Safety and regulatory considerations include allergy risk, organ toxicity (for example liver or kidney injury), and interactions with other drugs. Guidelines aim to optimize effectiveness while minimizing harm and resistance.