antibacterials

Antibacterials are substances that kill bacteria or inhibit their growth. The term covers antibiotics, antiseptics, and disinfectants. Antibiotics are medicines used to treat bacterial infections in humans and animals; they can be natural products, semisynthetic derivatives, or fully synthetic. Antiseptics are applied to living tissue to reduce or prevent infection, examples include chlorhexidine and iodine solutions. Disinfectants are used on inanimate surfaces to destroy bacteria, such as household bleach or alcohols.

Mechanisms of action vary. Many agents inhibit cell wall synthesis (beta-lactams like penicillins; glycopeptides such as vancomycin). Others inhibit protein synthesis (macrolides, tetracyclines, aminoglycosides). Some interfere with nucleic acid synthesis (quinolones, rifamycins), or disrupt cell membranes (polymyxins). Folate synthesis inhibitors (sulfonamides, trimethoprim) block essential metabolic steps. The choice of mechanism influences spectrum and resistance risk.

Spectrum and resistance: Antibiotics differ in their activity against particular bacteria; broad-spectrum agents affect many species, while narrow-spectrum drugs target specific groups. Bacteria can become resistant through mutations or by acquiring genes that encode enzymes (such as beta-lactamases), efflux pumps, or altered drug targets. Widespread use of antibacterials accelerates resistance, making stewardship important: use the right agent for the bug, prescribe the correct dose and duration, and avoid unnecessary or inappropriate prescriptions.

Safety and regulation: Antibacterials can cause adverse effects, including allergies, gastrointestinal upset, and disruption of the normal microbiota. Some have significant drug interactions or organ toxicity; monitoring and guidance from healthcare professionals are essential.