Bakteriisidal

Bakteriisidal, often anglicized as bactericidal, describes substances, typically antibiotics or antiseptics, that kill bacteria rather than merely inhibiting their growth. This property distinguishes them from bacteriostatic agents, which suppress replication and allow host defenses to clear the infection.

Bactericidal activity arises through diverse mechanisms: disruption of cell wall synthesis (examples include beta-lactams and glycopeptides), disruption of cell membranes (such as polymyxins and daptomycin), interference with DNA replication or repair (fluoroquinolones, metronidazole), or inhibition of essential metabolic enzymes. The outcome often depends on concentration, bacterial species, and growth phase; some agents are bactericidal for certain bacteria and bacteriostatic for others.

In laboratory testing, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) are used to characterize activity. An agent is considered bactericidal when the MBC is close to the MIC, typically within a fourfold difference. Time-kill studies assess how rapidly a drug reduces viable counts.

Uses include systemic antibiotics, topical antiseptics, and disinfectants. In clinical settings, bactericidal drugs are preferred when the immune system is compromised or when rapid bacterial clearance is needed. Efficacy depends on achieving sufficient drug levels at the infection site and may be reduced by biofilms, pH, or protein binding.

Limitations include the potential for resistance, toxicity to the host, and variation across species. Overuse and misuse contribute to resistance; appropriate selection, dosing, and duration are essential. See also antiseptics, disinfectants, and antibiotics.