Infection Control (ICE)
The chain and standard precautions
Infection control questions reward precision about categories. The chain of infection has six links: infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host. Every control you perform breaks one link. Standard precautions apply to every patient regardless of diagnosis, because a health history alone cannot reveal carriage; blood, saliva, and all body fluids are treated as potentially infectious.
Hands and PPE. Wash with soap and water when hands are visibly soiled or after contact with spore-formers such as C. difficile; an alcohol-based rub is acceptable otherwise. Gloves are single-use, are never washed or disinfected, and do not replace hand hygiene. Don PPE before contact and remove it without touching outer surfaces; change masks between patients or when damp.
Instrument processing. Follow the fixed order: transport in a closed container, clean with detergent (ultrasonic or scrub while wearing PPE), rinse, dry, inspect, package with an internal indicator, sterilize, then store. Never sterilize before cleaning, because bioburden shields organisms. Spaulding classification: critical items that touch bone or penetrate tissue must be sterilized; semicritical items are sterilized or high-level disinfected; noncritical surfaces receive low-level disinfection. Monitor sterilizers with mechanical gauges, chemical indicators, and a weekly biological spore test, using Geobacillus stearothermophilus for steam.
Surfaces, waste, and exposure. Use an EPA-registered hospital-grade disinfectant with a tuberculocidal claim, or barriers, and keep the surface wet for the labeled contact time. Flush waterlines and follow the 500 CFU/mL standard. Sharps go into a rigid container replaced at three-quarters full; regulated waste goes into red bags. After a needlestick, wash with soap and water, report immediately, document, and allow source-patient testing and consideration of post-exposure prophylaxis.
Trap
Any step that lets high-level disinfection slide, such as wiping an instrument with alcohol or disinfecting a handpiece instead of sterilizing it.
Rule of thumb
Clean first, then sterilize, and if an item touches bone or blood it is critical.