Disinfection Flashcards
sterilization
killing all organisms
germicide
agent for killing
disinfection
using a germicide on inanimate objects. does not imply killing all organisms
antisepsis
application of agents of surface of body to limit pathogens
septic
presence of pathogenic bacteria in living tissue
aseptic
tissue w/o pathogenic bacteria
sanitize
lowering bacterial content on fomites w/o using a germicide. use of heat is implied
perservative
inhibits growth of organisms. nontoxic and used in food and vaccines
phenol coefficient
killing capacity of an agent compared to phenol
greater than 1 means more effective than phenol
less than 1 means less effective than phenol
describe the descending order of resistance of various biological agents to germicidal chemicals
bacterial spores- mycobacteria- non lipid/small viruses- fungi- vegetative bacteria- lipid/medium sized viruses
first order kinetics killing curves for organisms
shows that the number of microbes killed is directly proportionate to the dose
change in killing kinetics w/ temp
increasing the temp decreases the time needed to kill
chlorohexidine
chlorinated phenol used as a surgical scrub
ethylene oxide
alkylating agent that destroys amino acids and hydroxyl groups. used to sterilize things that are heat sensitive
STERILAZTION
ethanol
disorganizes protein and lipids via hydrolysis reactions. 60-70% is optimal b/c water is necessary for the hydrolysis rxn
not as effective as iodine containing compounds
ANTISEPTIC
common uses: skin, antiseptics, germicides
isopropoanol
same uses as ethanol, but w/o legal restriction
iodine
tincure is a mix of iodine and KI in water
most effective antiseptic on skin
binds reactive tyrosine residues and forms inactive disulfide bridges on sulfur
ANTISEPTIC
chlorine
advantage- rapidly dissolves w/o scent
used in water supplies and food
ANTISEPTIC
detergents
destroy membranes and dissolve lipids
quaternary ammonium ions (or other cations) drawn toward negative charges on bacterial sufrace
ANTISEPTIC
hydrogen peroxide
particularly useful against anaerobes. action is inhibited by catalase
kills via ROS
ANTISEPTIC
soaps
surfactants containing hydrophobic/hydrophilic portions
mostly anionic detergents
physically remove bacteria rather than killing them
ANTISEPTIC
antibacterial soaps
active ingredient is triclosan
has a specific target that inhibits bacterial fatty acid synthesis
ANTISEPTIC
heavy metals
mercury and silver most common
mercury compounds bind SH groups
perservative used in vaccines
aldehydes
formaldehyde in vaccines- alkylation
glutaraldehyde - sterilizes syringes and blood
alternative preservative to heavy metals
heat
3 ways- moist heat, dry heat, pasteruization
wet heat- complete sterilzation caused by steam under pressure- autoclave. pressure allows you increase temp while keeping fluid state. unsuitable for heat sensitive materials.
spores are resistant to boiling
dry heat- good for materials damaged by water. much higher temp over longer duration. 180 C for 2 hours
pasteurization- classically- 62 C for 30 minutes (milk in america)
HTST- used in europe 71-72 for just 15-17 seconds.
sterilizing prions
autoclave w/ NaOH, 121 C, for 30 minutes
tests for effective pasteurization
loss of alkaline phosphatase activity
negative culture for coxiella burnetti
filtration
used for heat sensitive liquids. allows retention of high quality, no effects of heat treatment. can be used quickly for smal samples
drawbacks- expensive, clogged filters, most viruses pass through all common filters
nonionizing radiation
nonionizing radiation- (UV light) used in operating rooms or bio hoods
causes thymidine dimers that interfere w/ DNA replication
causes peroxide formation
advantages- cheap and contained
disadvantages- non-penetrating, damages human tissue
ionizing radiation
xray, gamma rays, high enery, not widely used, except some food
disadvantage- containment
drying
lowers water level below requirement for bacterial growth
can be done by salt and sugar- osmotic agents that dry
dyes
MOA unknown
used as an antifungal for athletes foot infections
