Cleaning, Sterilization, Disinfection, and Environment of Care
Spaulding classification
Critical items enter sterile tissue or the vascular system (surgical instruments, implants, catheters) and require sterilization. Semicritical items contact mucous membranes or non-intact skin (endoscopes, laryngoscopes, bronchoscopes, transvaginal probes) and require high-level disinfection at minimum. Noncritical items touch intact skin (stethoscopes, blood pressure cuffs, bed rails) and need low-level disinfection. Cleaning always comes first - organic soil inactivates disinfectants and protects biofilm.
Sterilization and monitoring
Common methods are steam (121°C for 15 minutes or 132°C for 4 minutes), ethylene oxide, hydrogen peroxide gas plasma, and peracetic acid. Every load is monitored three ways: mechanical (time, temperature, pressure), chemical indicators (internal and external), and biological indicators - Geobacillus stearothermophilus for steam and hydrogen peroxide, Bacillus atrophaeus for ethylene oxide and dry heat. A positive biological indicator means quarantine the load, recall it, and investigate; implants ideally wait for BI results before release.
HLD and the environment
Glutaraldehyde and ortho-phthalaldehyde require strict exposure time. Endoscopes need leak testing, manual cleaning, high-level disinfection, alcohol purge, and vertical storage with a defined maximum hang time. Environmental cleaning targets high-touch surfaces with an EPA-registered product at the labeled contact time; C. difficile spores require a sporicide such as bleach plus friction. Routine environmental culturing is not recommended. Construction and renovation require an infection control risk assessment, water management for Legionella, and air pressure control.
Traps
Match organism to sterilizer, never confuse a chemical indicator with a biological one, and never shorten contact time.
Rule of thumb: Classify the device, then the process, then check the monitoring - if the biological indicator fails, nothing in that load is released.