Antisepsis and Sterilization Flashcards
- Define germ theory and recall Koch's Postulates - Discuss the concept of healthcare-associated infections - Compare and contrast disinfection, antisepsis, and sterilization - Define bacteriostatic and bacteriocidal agents - Recall chemical and physical methods of decontamination and how each agent works and is used
What is germ theory?
microorganisms cause disease
What are Koch’s postulates?
- microbes must be present in all disease cases
- microbe must be isolated from the infected host and grown in pure culture
- when a pure culture is introduced into a susceptible host, the disease must be reproduced
- microbes must be isolated from a purposely infected host.
What is nosocomial infections?
Those infections whose onset and confirmation occurs greater than 48 hours after hospital admission.
“hospital acquired”
Can healthcare associated infections be long term?
Yes, occuring within 6-12 months of systemic antibiotic treatment, long-term care facilities, central IV, urinary catheter, dialysis
What are some reasons for high rates of hospital infections?
high prevalence of pathogens, compromised patients, efficient transmission from patient to patient by hospital personnel.
What is the single most important method to limit transmission of nosocomial agents?
proper hand hygiene
Define disinfectant
a physical or chemical agent used to inhibit or destroy microorganisms on inanimate objects.
Define antiseptic
a physical or chemical agent used to inhibit or destroy microorganism on SKIN or TISSUE.
An agent that inhibits bacterial growth is called
bacteriostatic
An agent that destroys or inactivates bacteria is called
bactericidal
What are some examples of chemical agents?
phenolics, alcohol, halogens, surfactants, aldehydes, oxidizing agents
How do phenolics and alcohol work?
denature proteins and disrupt cell membrane
How does halogen work?
iodine is an example. It works by iodinating or oxidizing bacterial proteins. Chlorine oxidize proteins too.
What is more effective against bacteria, spores and viruses: halogen or phenolics/alcohol?
halogens, because phenolics and alcohol are ineffective against spores, non-enveloped viruses, and protozoans cysts.
How does surfactant work?
contains hydrophobic and hydrophillic groups and perturb cell membrane
Define sterilization
complete killing or removal of all living organisms from an item or area
How is sterilization best accomplished?
physical methods (bacteria are killed exponentially over time)
What are some examples of physical methods?
heat, cold, filtration, radiation
How does heat work?
HIgh temperatures denature proteins, reduce integrity of cell membrane and denature DNA
Moist or dry heat kills most rapidly?
moist heat because reactive water molecules denatures proteins by disrupting H bonds formed b/w amino acids.
What is the most efficient way to sterilize ?
autoclave
What does boiling do?
It does NOT sterilize but kills mostly everything except spores or cysts
How does pasteurization work ?
It does not sterilize but involves heating then rapid cooling. No effects on spores
How do filters work?
it removes live and dead bacteria from liquid. However, viruses can pass through.
How do nonionizing radiation work?
UV rays is sterilizing because it excites e- and leads to formation of T-dimers in DNA. Typically used to disinfect air and surfaces in hospital
Shorter or longer wavelenghts are more damaging?
shorter b/c it provides more energy and better cell penetration. it can damage DNA and produce free radicals, H2O2. Short waves are ionizing radiation, used in sterilization of surgical tools