RA1: Sterilization, Disinfection, & Antisepsis Flashcards
What are the highest incidence HAIs in recent years?
Antibiotic-resistant Gram positive bacteria and multi-drug resistant Gram negative
Sources of HAIs
- Human (self, other patients, staff, visitors, etc.)
- Environment (fomites, food, water, air)
- -Same routes of infection as other places and same organism can be transmitted by more than one route
Methods for prevention of infection
- Sterilization (most effective)
- Disinfection
- Antisepsis (least effective)
- Pasteurization (used for liquids)
What is sterilization used for?
Total destruction or physical removal of all microorganisms
Methods of sterilization
- -Moist heat
- -Dry heat
- -Ethylene oxide gas
- -Irradiation
Sterilization technique uses: moist heat
Often done with an autoclave, most widely used and most dependable; kills microbes by irreversibly denaturing proteins to cause single strand DNA breaks and compromise membrane integrity (NOT THE SAME AS BOILING!)
How can prions be killed?
Boiling in NaOH for ten minutes then extended autoclaving
Sterilization technique uses: dry heat
Done in oven, kills spores but not pyrogens (fever-inducing agents), used for materials that can be damaged by moist heat; kills microbes by irreversibly denaturing proteins to cause single strand DNA breaks and compromise membrane integrity
Sterilization technique uses: ethylene oxide gas
Used for heat- and moisture-sensitive medical devices; kills by alkylating protein, DNA and RNA within cells to prevent normal cellular metabolism and replication
Sterilization technique uses: irradiation
Used in lab safety cabinets, hospital operating rooms, ionizing, prevention of growth in water in apparatus like auto-analyzers; kills by eliciting DNA damage through production of free radical to block microbial replication
What is disinfection used for?
Removing or killing most, but not all, viable organisms (normally doesn’t kill mycobacteria, viruses, fungi, or bacterial spores)
High-level disinfection
Destroys all microorganisms except large numbers of bacterial spores and used for all devices that cannot be sterilized (ex. endoscopes, plastic surgical devices)
High-level disinfectants
Glutaraldehyde, oxidizing agents such as peracetic acid, hydrogen peroxide, and chlorine compounds
Intermediate-level disinfection
Not very effective against bacterial spores, used on semi-critical instruments that come into contact with mucus membrane or non-intact skin
Intermediate-level disinfectants
Alcohols, iodine-containing compounds (iodophors), phenolic compounds
Low-level disinfection
Can only kill most vegetative bacteria, clean non-critical instruments that contact only intact skin
Low-level disinfectants
Quaternary ammonium compounds
What is antisepsis used for?
Disinfection of skin surfaces to lower number of microorganisms
Types of antiseptic agents
- -Alcohols
- -Phenolic compounds
- -Iodine-containing solutions
- -Chlorhexidine
- -Quaternary ammonium compounds
- -Triclosan
Alcohols (antisepsis)
- -Ex. ethanol and isopropanol
- -Kill most microbes but not spores
- -Act by denaturing bacterial proteins or inhibiting synthesis of metabolites essential for rapid cell division
- -Clean skin before poking with needle
Phenolic compounds (antisepsis)
- –Act by penetrating and disrupting cell wall in high concentrations and denaturing proteins and lipids in cell membranes to lyse cell
- -Kill most microbes but not spores
Iodine-containing solutions (antisepsis)
- -Most effective skin antiseptics
- -Kill many microorganisms but not spores
- -Quickly penetrate cell wall of microorganisms and cause disruption of proteins and nucleic acid structure and synthesis
Two major types of iodine (antisepsis)
- Tincture of iodine – prepares skin prior to blood culture but irritates skin
- Iodophors – combination of iodine and stabilizing agent or carrier (ex. povidone iodine); non-toxic
Chlorhexidine (antisepsis)
- -Broad antimicrobial activity but slower rate of killing than alcohols
- -Membrane disruption is method of killing (no spore killing)
- -Prevents bloodstream infections in patients with central lines better than iodine
Quaternary ammonium compounds (antisepsis)
- -Ex. benzalkonium chloride
- -Not very efffective
- -Attack energy-producing enzymes, denature cell proteins and disrupt cell membranes
Triclosan (antisepsis)
- -Found in antiseptic soaps and some toothpastes
- -Active against bacteria including mycobacteria but not spores
- -Works by inhibiting bacterial lipid synthesis and disrupting cell membrane at high concentrations
