chapter 10 pt 2 Flashcards
physical methods of control
heat, cold, desiccation, radiation, filtration
moist heat
lower temp than dry heat and shorter exposure time
-coagulation and denatures proteins
dry heat
high temperature, dehydrates so proteins cant fold, incineration
thermal death time
shortest length of time needed to kill all test microbes at a specific temperature
thermal death point
lowest temp to kill microbes in a sample in ten minutes
moist heat methods
-sterilization from steam under pressure
-autoclave 121 celsius for 10-40 min
-steam has to reach the surfaces
-cant be heat sensitive item
-denatures proteins and destroys membranes and DNA
nonpressure steam
tyndallization
-disinfectant
-canned foods and lab media
tyndallization
intermitten sterilization for things that cant stand autoclave
-free floating steam for 30 - 60 minutes to kill vegetative spores then incubate and steam again
why repeat cycle for 3 days of incubating and steaming for tyndallization?
bc vegetative can come back from germination
-this is NOT sterilization bc not killing spores just vegitative state
boiling water
100 celsius for 30 minutes for non spore forming pathogens
-disinfection
pasteurization
heat without destroying milk
-63-66 degress for 30 min (batch)
-71 for 15 seconds (flash)
-NOT sterilization doesnt kill spore forming pathogens and many nonpathogenic microbes
-just lowers microbe count
dry heat is
flame or electric heating coil
-a dry oven will coagulate/ dehydrate proteins
is cold good for killing?
no it preserves microbes
-slows growth
-preserves food and mecia and cultures
-when thaw microbe resumes growth
dessication
remove water molecules for metabolic inhibition
-preservation technique
-not useful bc many cells can grow w out water
lyophilization
freeze drying to preserve
-type of desiccation
-freeze dry yeast
ionizing radiation
deep pentrating power that can force electrons out of orbit therefore breaking DNA
-gamma rays, x rays, cathode rays
-sterilize medical supplies and food (rasberries)
nonionizing
-uv
-little pentration
-object has to be directly exposed (lab)
-pyrimidine dimers
what can nonionizing sterilize?
water, air and surfaces
filtration
physical removal of microbes through a filter
-mask that blocks droplets or bacterial and viruses
-good for heat sensitive liquids and hostpial air
-doesnt kill just traps microbesz
chemical methods of control
-disinfectant
-antiseptics
-sterilants
-degermers
-preservatives
advantages of chemicals
-fast in low concentrtions
-water or alcohol soluble (stable)
-low toxicity
-penetrating
-noncorrosive and nonstaining
-afforable and available
chemical levels
-high level germicides
-intermediate level
-low lever
high level germicide
-kill endospores
-MIGHT be sterilants
-good if object cant take heat of autoclave
-things going into the body
intermediate level
kill fungal spores NOT endospores, tubercle bacillus and viruses
-disinfect devices that contact mucous membranes but are not invasive devices
-kills what will make you sick
low level
eliminate only vegitative bacteria
-some viruses and vegitative fungal cells
- to clean surfaces that touch skin but not mucous membranes
what affects germicidal activity of chemicals?
-nature of material being treated
-degree of contamination
-time of exposure
-strength and chemical action of the germicide
germicidal categories
-halogens
-phenolics
-chlorhexidine
-alcohol
-hydrogen peroxide
-aldehyde
-gases
-detergent and soap
-heavy metals
-dyes
-acids and alkalines
chlorine
-chlorine
-hypochlorites (bleach)
-denatures porteins by messing with disulfide bonds
-intermediate level so cant kill spores
-unstable in sun and inactivated by organic material (Pee and poo)
chloramines
when chlorine is inactive
halogens
chlorines and iodines
iodine
-iodophors (betadine)
-messes up disulfide bonds
-intermediate level
-milder medical and dental degerming agents, disinfectants and oinments
phenolics
-lysol
-cell wall and proteins
-low to intermediate level
-bactericidal, fungicidal, viricidal NOT sporicidal
-triclosan additive to soap
chlorhexidine
-hospitals
-surfactant and protein denaturant
-low to intermediate
-hibiclens and hibitane
-antiseptic for or scrubs, skin clearning, burns. handwashing in hospital, cosmetic creams, toothpaste, eye drops, deodorant, mouthwash
-controls MRSA and acinetobacter in hospitals
alcohols
ethyl or isopropyl 50-95%
-acts like surfactant to dissolve me,brane ;lipids and coagulating proteins of vegetative bacterialc ells and funi
-intermediate level
-best is 70% bc u need water to coagulate proteins
hydrogen peroxide
makes hydroxyl free radicals that damage protein and DNA while it also decomposes to oxygen
-toxic to anaerobes
-low conceptration is antispetic
-high concentration is sporicidal, bactericidal, viricudal, fungicidal
-sterilizes medical equipment (dental tools and endoscopes)
high concentration of hydrogen peroxide
strong and dangerous
aldehydes
alkylates proteins and DNA
-glutaraldehyde and formaldehyde
-rapid and effective
gluteraldehyse
in 2 % it is used as a sterilant for heat sensitive instruments
-high level
formaldehyde
disinfectant, presercative, toxic
-formalin is 37% aqueous
-intermediate to high level
gases and aerosols
ethylene oxide and propylene oxide
-strong alkylating agents
-high level
-disinfect and sterilize plasmic and devices and food
-things that cant be autoclaves or exposed to steam/ heat?
detergent and soaps
quaternary amonia compounds that are surgactants altering membrane permeability of bacteria and fungi
-cationic detergent
-low level
heavy metals
solutions of silver and mercury kill vegitative cells in low concentrations by inactivating proteins
-oligodynamic action
-low level
what are the metals
merthiolate, silver nitrate and silver
-toxic if ingested or absorbed
what is silver added to?
catheters, IV lines, and prostheses to prevent biofilms and infections
dyes
aniline dyes have antimicrobial components
-active against gram positive bacteria and fungus
-antisepsis and wound treatment
-low level
acids and alkalis
low level
-organic acids present spore germination, bacterial and fungal growth
-food preservation
acetic acid
bacterial growthp
propionic acid
retards mold
-retard my mold y te doy una propina
lactic acid
anerobic bacterial growth
-lack oxy
benzoic and sorbic acid
inhibit yeast
sodium hydroxide
destroys prions
ceviche
cooked by citrus bc the ph kills microbes
