Sterilization and Disinfection... Flashcards
Sterilization
total destruction or physical removal of all microorgamism
Moist heat
most widely used/dependable method of sterilization
How does moist heat kill microbes
by irreversibly denaturing proteins, compromising membrane integrity
Dry heat
kills spores but may not eliminate pyrogens
When is dry heat used
only for materials that can be damaged by moist heart or where moist heat can’t get to
How does dry heat kill microbes
by irreversibly denaturing proteins, compromising membrane integrity
Ethyele oxide gas
colorless gas that is highly toxic, flammable and explosive
When is ethyele oxide gas used
for heat and moisture sensitive medical devices without deleterious effects on the material used
How does ethylene oxide gas kill microbes
by alkylating protein, DNA, and RNA within cells, which prevents normal cellular metabolism and replication
UV Irradation
used in laboratory safety cabinets, hospital operating rooms, ionizing, prevention of growth in water in apparatus, inefficient as a sterilant
Ionizing radiations
used to sterilize heat sensitive, pre-packed, single use plastic items
How do ionizing radiations kill microbes
by eliciting DNA damage through production of free radical, blocks microbial replication
Disinfection
process of removing or killing most, but not all, viable organisms. More resilient organisms like mycobacteria, viruses, fungi and bacterial spores may survive these procedures.
Factions that influence effectiveness of disinfection
i. Nature of the item to be disinfected
ii. Concentration of disinfectant
iii. Duration and temp of exposure
iv. Number and resilience of the containing orgasm
v. Amount of organic material present on the device, which can inactivate the disinfectant
HIgh level disinfection
can kill everything except lots of spores
What is high level disinfection used for
all devices that can’t be sterilized
examples of high level disinfection
glutaraldehyde, oxidizing agent
Intermediate level disinfection
i. can kill mycobacteria, bacteria, most viruses, most fungi but are not very effective against bacterial spores.
Examples of intermediate level disinfection
alcohols, iodine containing compounds (iodophors), phenolic compounds
When is intermediate level disinfection used
semi-critical instruments which are unlikely to be contaminated with spores and only come into contact with mucus membranes or non-intact skin
low level disinfectants
can kill most vegetative bacteria, some fungi, and some viruses in a reasonable period of time
Examples of low level disinfectants
quaternary ammonium compounds
Antisepsis
Antiseptic agents are disinfectants used to lower the number of microorganisms on skin surfaces. None of these agents kill bacterial spores however they are all very efficacious against vegetative bacteria and are very safe.
Alcohols
kill most microbes but not spores
no residual killing effect
readily inactivated by organic matter
not as affective as iodine containing compounds
How do alcohols lower number of microbes
denaturation of bacterial proteins, but can also inhibit the synthesis of metabolites essential for rapid cell division
Which type of alcohol is more effective - 70% or 95%
70%
How do phenolic compounds work
penerate and disrupt the cell wall in high conc.
denature proteins and lipids within the cytoplasmic membrane
lyse cells
rarely used
antimicrobial action improved by halogens
Iodine containing solutions
most effective
need before obtaining a blood culture and when putting in caths
Ticture of iodine
good for before a blood culture, but irritates skin
iodophors
stable, non-toxic for skin and tissue
How is the toxicity of iodine compared to alcohols
slightly more toxic
how does iodine work
can quickly penetrate the cell wall of microorganisms and cause disruption of proteins and nucleic acid structure and synthesis
Clorehexidine
has broad antimicrobial activity but slower rate of killing than alcohol
How does clorehexidine work
membrane disruption
When is chlorehexidine used
for general skin cleaning, a surgical scrub, and pre-operative skin prep
Resideual activity of chlorehexidine
some residual activity, but diminished by organic matter and high pH
Quaternary ammonium compounds
attack energy producing enzymes, denature cell proteins and disrupt the cell membranes
not very effective
Triclosan
found in antiseptic hand soap, toothpaste
active against bacteria, but not spores
How does triclosan work
inihibts bacterial lipid synthesis and may also disrupt the cell membrane at high concentration
