Topic overview

Start with the big picture

Selective toxicity is the basis of chemotherapy: drugs exploit differences between target cells and host cells, while the therapeutic index describes the safety margin between toxic and therapeutic doses. Antimicrobials can be grouped by the organisms they target and by spectrum, and antibacterial drugs act through several major mechanisms. Treatment choices also depend on whether a drug is bactericidal or bacteriostatic, how it reaches and persists at the infection site, and measures such as MIC and MBC. The broader framework includes post-antibiotic effects, interactions between drugs, resistance mechanisms, superinfection, and chemoprophylaxis. Host factors—including age, pregnancy, organ function, and immune status—are part of antimicrobial selection.