Antiseptics & Disinfectants

Antiseptics & Disinfectants

1. Definitions & terminology

• Antiseptic vs disinfectant — both are agents that inhibit or kill microbes on contact; the distinction is conventional and based on the surface of application, not on intrinsic chemistry (KDT 8e Ch.67, p.957).
• Antiseptic — agent applied to living surfaces (skin, mucous membranes — mouth, wounds); has sufficiently low toxicity for host cells to be used directly on skin, mucosae or wounds (KDT 8e Ch.67, p.957; Katzung 16e Ch.50, p.947).
• Disinfectant — agent used on inanimate (non-living) objects — surgical instruments, surfaces, privies, water supply (KDT 8e Ch.67, p.957; Katzung 16e Ch.50, p.947).
• There is considerable overlap; many agents are used either way. A practical "static vs cidal" distinction between the two is futile because these actions are frequently concentration-dependent (KDT 8e Ch.67, p.957).
• Germicide — umbrella term covering both antiseptics and disinfectants (any agent that kills microbes) (KDT 8e Ch.67, p.957).
• Sterilant — agent (or physical process) that kills both vegetative cells AND spores when applied to materials for an appropriate time and temperature; the most stringent category (Katzung 16e Ch.50, p.947).
• Disinfection vs sterilization — a key examination distinction (KDT 8e Ch.67, p.957; Katzung 16e Ch.50, Table 50–2, p.948):
• Sterilization — a process intended to kill or remove ALL types of microorganisms, including spores (and usually viruses), with an acceptably low probability of survival.
• Disinfection — chemical/physical treatment that destroys most vegetative microbes and viruses but NOT spores, in or on inanimate surfaces; reduces viable pathogens to a level posing no risk to a host with normal defences. Disinfectants do NOT eliminate all microbes (do not kill spores).
• Related terms (Katzung 16e Ch.50, Table 50–2, p.948; KDT 8e Ch.67, p.957):
• Antisepsis — application of an agent to living tissue to prevent infection.
• Decontamination — a process producing a marked reduction in the number/activity of microorganisms.
• Sanitization — reduction of microbial load on an inanimate surface to a level acceptable for public-health purposes.
• Pasteurization — kills non-sporulating organisms by hot water or steam at 65–100 °C (Katzung) / moderate heat over time (e.g. water + moderate heat).
• Historical note — the era of antiseptics/disinfectants was heralded by Semmelweiss (hand-washing in chlorinated lime) and Lister (antiseptic surgery using phenol) in the 19th century (KDT 8e Ch.67, p.957).
• Distinction from systemic antimicrobials — germicides differ from systemically used antimicrobials by their low parasite selectivity — they are too toxic for systemic use. Some antibiotics (bacitracin, neomycin, mupirocin) are restricted to topical use but are conventionally not enumerated with antiseptics; a strict distinction is impossible (KDT 8e Ch.67, p.957).