Difference between Sterilization, Disinfection, Antisepsis, Germicide, Decontamination and Cleaning

Sterilization is the process of complete elimination or destruction of all forms of microbial life (i.e., both vegetative and spore forms), by either physical or chemical methods.

• Chemical sterilant: These are chemicals used for a longer duration (3–12 h) to destroy all forms of microbes, e.g., peracetic acid (PAA) (0.2%), glutaraldehyde (≥2.4%), ortho-phthalaldehyde (OPA) (0.55%), and hydrogen peroxide (7.5%).
• Example is Autoclave: (Steam under atmospheric pressure) Sterilization for 121⁰ C at 15 psi Pressure for 15 minutes.

Disinfection is defined as a process of complete elimination of vegetative forms of microorganisms except the bacterial spores from inanimate objects. It is further classified into high-, intermediate-, and low-level disinfection.

• High-level disinfectant (HLD): Used for shorter duration and able to kill 10⁶ log microorganisms except spores, e.g., glutaraldehyde (≥2.0%), OPA (0.55%), hydrogen peroxide (7.5%), hypochlorite (650–675 ppm), and hypochlorous acid (400–450 ppm).
• Intermediate level disinfectant (ILD): These disinfectants act against Mycobacterium tuberculosis and are mainly used for noncritical items contaminated with blood/body fluids.
• Low-level disinfectant (LLD): LLDs are used to remove the vegetative form of bacteria, few fungi, and some enveloped viruses from the noncritical items, e.g., 3% hydrogen peroxide, quaternary ammonium compound, diluted glutaraldehyde, phenolics, etc.

Antisepsis: prevention of infection on wound (living tissue) by inhibiting growth of bacteria by chemical agents like providone iodine, chlorhexidine. When it is related to the patient’s skin, it means disinfection of living tissue or skin. When it is related to the health care worker, it means reduction or removal of transient microbe from the skin.

Germicide: It is the agent that destroys germs. It includes both antiseptics and disinfectants. The type of microorganism is identified from the prefix (e.g., virucide, fungicide, bactericide). Handwash containing providone iodine is both virucidal and bactericidal.

Decontamination is the process of removal of pathogenic microorganisms from objects so that they are safe to handle or a space safe to occupy.

Cleaning is defined as removal of visible soil (e.g., organic and inorganic materials) from the surfaces and objects. It involves washing (with soap and cold water) and scrubbing (mechanical action).

Reference: Mohapatra S. Sterilization and Disinfection. Essentials of Neuroanesthesia. 2017:929–44. doi: 10.1016/B978-0-12-805299-0.00059-2. Epub 2017 Mar 31. PMCID: PMC7158362.