Disinfection work, disinfection, disinfection, deratization, sterilization of medical instruments.
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CDC disinfection sterilization medical instruments environmental infection control guidelines
Key terms
| Term | Meaning | Main target |
|---|---|---|
| Cleaning | Physical removal of dirt, blood, secretions, and organic material using water and detergent | Reduces microbial load. It must come first because organic material can protect microorganisms from chemicals or heat. |
| Disinfection | Destruction of many or all pathogenic microorganisms on inanimate objects, but not reliably bacterial spores | Patient-care equipment and environmental surfaces |
| Sterilization | Validated process that destroys or removes all forms of microbial life, including bacterial spores | Critical reusable medical instruments |
| Disinsection | Control or destruction of insects and arthropods that may transmit disease, such as mosquitoes, lice, fleas, cockroaches, and flies | Vector control |
| Deratization | Control or elimination of rodents, especially rats and mice | Prevents rodent-borne disease and contamination |
Disinfection
Disinfection applies to inanimate objects, not living tissue. For skin or mucosa, the correct term is usually antisepsis.
Levels of disinfection
-
High-level disinfection
- Kills all microorganisms except a high number of bacterial spores.
- Used for semicritical items that contact mucous membranes or non-intact skin, for example flexible endoscopes and some respiratory equipment.
- Examples include appropriately used glutaraldehyde, ortho-phthalaldehyde, hydrogen peroxide, and peracetic acid.
-
Intermediate-level disinfection
- Kills mycobacteria, vegetative bacteria, most viruses, and fungi, but not necessarily spores.
- Commonly used for surfaces contaminated with blood or body fluids.
-
Low-level disinfection
- Kills most vegetative bacteria and enveloped viruses, plus some fungi.
- Used for noncritical items such as blood-pressure cuffs, bed rails, examination tables, and stethoscopes, depending on local protocol.
The effectiveness of chemical disinfection depends on prior cleaning, concentration, contact time, temperature, pH, water quality, the type and number of microorganisms, and the presence of organic matter. CDC guidance stresses that cleaning before disinfection or sterilization is necessary for reliable results. See the CDC disinfection guideline.
Choosing the method: Spaulding classification
| Device category | Contact during use | Required processing | Examples |
|---|---|---|---|
| Critical | Enters sterile tissue or vascular system | Sterilization | Surgical instruments, implants, vascular and urinary catheters |
| Semicritical | Contacts mucous membranes or non-intact skin | At least high-level disinfection, preferably sterilization if compatible | Endoscopes, laryngoscope blades, respiratory therapy equipment |
| Noncritical | Contacts intact skin only | Cleaning plus low- or intermediate-level disinfection as indicated | BP cuffs, ECG leads, bed rails |
This risk-based approach is described in the CDC Spaulding classification guidance.
Sterilization of medical instruments
Standard workflow
- Point-of-use pre-treatment: prevent blood and debris from drying on the instrument.
- Transport safely: use closed, labelled, leak-resistant containers.
- Cleaning: manual cleaning, ultrasonic cleaning, or washer-disinfector.
- Rinsing and drying: residual moisture can impair packaging and sterilization.
- Inspection and assembly: check cleanliness, function, hinges, lumens, and integrity.
- Packaging: use packaging compatible with the sterilization method.
- Sterilization cycle: select a validated method suitable for the device and manufacturer instructions.
- Monitoring and release: use physical, chemical, and biological indicators.
- Storage and distribution: protect packs from moisture, damage, dust, and excessive handling.
Main methods
| Method | Typical use | Notes |
|---|---|---|
| Steam sterilization under pressure | Most heat- and moisture-stable instruments | Preferred method for many surgical metal instruments because it is effective, rapid, and non-toxic. |
| Dry heat | Glassware, powders, oils, moisture-sensitive metal items | Requires higher temperatures and longer exposure than steam. |
| Ethylene oxide gas | Heat- and moisture-sensitive complex devices | Effective at low temperature but requires strict aeration and occupational-safety controls. |
| Hydrogen peroxide gas plasma/vapor | Many heat-sensitive devices | Fast low-temperature option, but device materials and lumen specifications must be checked. |
| Peracetic acid systems | Some immersible instruments, including selected endoscopic equipment | Often processes items for immediate use rather than packaged storage. |
| Filtration | Heat-sensitive fluids and gases | Removes microorganisms rather than killing them. |
Monitoring sterilization
- Physical monitoring: time, temperature, pressure, and machine records.
- Chemical indicators: placed outside and inside packages to show exposure to the process.
- Biological indicators: spores with high resistance to the sterilization process. They provide the best direct evidence that a cycle can kill resistant microorganisms.
- A failed biological indicator requires investigation, possible recall of affected loads, and reprocessing according to facility policy.
Do not reprocess a device labelled single-use unless this is permitted by applicable regulation and an approved reprocessing system. Follow the device manufacturer’s instructions for use.
Disinsection
Disinsection interrupts transmission by insects and other arthropods. Measures include:
- Removing breeding sites, such as standing water for mosquitoes.
- Environmental sanitation and waste management.
- Screens, protective clothing, bed nets, and repellents.
- Mechanical methods such as traps.
- Targeted use of approved insecticides.
- Surveillance for vectors and resistance to insecticides.
Disinsection is particularly relevant to diseases such as malaria, dengue, leishmaniasis, plague, typhus, and other vector-borne infections.
Deratization
Deratization controls rats and mice, which can spread pathogens through urine, feces, bites, fleas, food contamination, and environmental contamination.
Core measures
- Rodent-proofing: seal gaps, repair doors, screens, drains, and wall openings.
- Remove food and water sources: covered food storage, prompt refuse removal, eliminate leaks.
- Reduce harbourage: clear clutter, vegetation, and debris near buildings.
- Trapping: mechanical traps are useful for monitoring and control.
- Rodenticides: use only through trained personnel and in secure bait stations to prevent harm to children, patients, pets, and non-target animals.
- Safe cleanup: do not sweep or vacuum dry rodent droppings. Wet them with an appropriate disinfectant first, then remove using gloves and dispose safely.
Practical distinction
- Surface contaminated with blood: clean, then disinfect using an appropriate product and full contact time.
- Reusable surgical forceps: clean thoroughly, inspect, package, and sterilize.
- Flexible endoscope: meticulous cleaning followed by high-level disinfection or sterilization as required by the device instructions.
- Rat infestation in a hospital storeroom: deratization plus sanitation and structural exclusion.
- Mosquito breeding near a facility: disinsection through source reduction and vector-control measures.
A recent systematic review of central sterile supply departments supports the importance of standardized workflows, trained staff, and quality assurance for safe instrument reprocessing (PMID 40168376).
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