Disinfection: Types and Physical Methods
The term is derived from the French des (removal) and the Latin infectio (infection). Unlike sterilization, disinfection eliminates only the majority of pathogenic microorganisms, whereas bacterial spores and particularly resistant forms may survive.
Depending on the epidemiological situation, three types of disinfection are distinguished:
- Prophylactic — performed regularly to prevent the emergence of diseases even in the absence of known cases.
- Concurrent (focal) — carried out at the bedside of an infected patient to reduce pathogen concentration in the environment.
- Terminal — required for complete decontamination of a focus after the source of infection has been removed (e.g., following hospitalization, recovery, or death).
Thermal methods are widely used for decontamination: boiling, hot steam treatment in washer-disinfectors, and flaming (dry heat). For liquid foods, pasteurization is employed—short-term heating at various temperature regimes (from 61.5 °C to 150 °C). Germicidal lamps are actively used in medical and industrial facilities. They generate ultraviolet radiation that effectively purifies air and working surfaces.
Chemical Disinfection
If an object cannot withstand high temperatures (thermolabile instruments, skin, room surfaces, water), chemical agents are utilized. They dissolve cellular lipid membranes or disrupt microbial proteins and nucleic acids.
Based on their mechanism of microbial cell damage, disinfectants are divided into four groups:
- Destructive — cause dissolution (lysis) or protein denaturation.
- Oxidizing — act via active oxygen or halogens (hydrogen peroxide, potassium permanganate).
- Membrane-attacking — disrupt cell wall permeability (includes detergents).
- Anti-enzymatic — block internal bacterial enzyme systems (heavy metal salts, 8-hydroxyquinolines).
For volumetric decontamination of equipment and devices, gas mixtures (e.g., ethylene oxide with methyl bromide) may be applied.
Asepsis: Preventing Contamination
Asepsis refers to a system of measures designed to prevent microorganisms from penetrating (contaminating) a wound, patient tissues, or medical devices. This is critically important in surgery, microbiological production, and the food industry.
Asepsis is implemented through a complex of barriers:
- Maintaining sterility — exclusive use of sterile linens, instruments, and dressings.
- Disinfection measures — thorough scrubbing of staff hands and the operative field.
- Barrier protection — wearing masks, gloves, and specialized clothing.
- Organizational solutions — room zoning (isolation boxes), installation of specialized ventilation systems.
Antisepsis: Combating Infection at the Focus
Antisepsis is a complex of therapeutic actions aimed at destroying microbes that have already penetrated the body, a wound, or a pathological focus.
Depending on the approach, antisepsis is divided into four types:
- Mechanical — physical removal of dead (necrotic) tissues, infected areas, and foreign bodies from a wound.
- Physical — ensuring the outflow of infected contents using drains, tampons, and hygroscopic dressings.
- Biological — application of enzymes to break down non-viable tissues, as well as specific agents (antibiotics, bacteriophages) for direct pathogen destruction.
- Chemical — application of antimicrobial agents (antiseptics) to drastically reduce the microbial population. This includes halogens (iodine and chlorine preparations), oxidizers, acids and alkalis, alcohols, dyes (e.g., brilliant green), and detergents (chlorhexidine).