9 Flashcards
2 types of sterility tests
membrane filtration test and direct inoculation
membrane filtration test 3 steps
- filtration though 0.45 micrometer filter
- culture
- incubate
what does filtration do in membrane filtration sterility testing
it removes preservatives or ABs that may inhibit growth or cause turbidity
3 steps in direct inoculation sterility testing
- aseptic removal of sample
- inoculation in culture medium
- incubation
3 issues w direct inoculation method
- small volume of product causes low sensitivity
- may need neutralisation of product has antomicorbial properties
- cloudy sample can affect reading
dry heat sterilisation os good for
materials that may be damaged by moist heat or are impenetrable tp moms heat eg powders, petroleum products and sharp instruments
which is of the 2 types of dry heat sterilisation methods is better
forced air is better than static air
temperature used for dry heat sterilisation
220 degree celsius
which method of sterilisation can remove endotoxins
dry heat sterilisation
what are examples of chemical sterilants
ethylene oxide, peracetic acid, h2o2 fog, formaldehyde
issues w ethylene oxide
possible carcinogen
eye pain sotre throat, convulsions
flammable and explosive
ethylene oxide residue
removed via aeration
peracetic acid efficacy in organic soil
remains but reduced
activity of peracetic acid
fungi, bacteria and yeast
not viruses
peracetic acid must be combined with
anticorrosive agent eg sulfonate
temp round 50C
H2o2 plasma temperature
37-44 (lowest of all chemical sterilants)
range of efficacy of h2o2 plasmas
wide range including, Cdif, mycobacteria, MRSA
byproduct toxicity of h2o2 plasma
non toxic byproducts water and oxygen
issue w h2o2 plasma
low penetration so yo need a penetration enhancer
Gamma radiation uses
cobalt 60
cesium 137
electron accelerators
temp of gamma radiation
not raised at all
Mao of gamma radiation
disrupts nucleic acids
gamma radiation is not suitable for
can also cause
aqueous products with proteinaceous component
possible delimitation, oxidation and cracking in polyethylene
ozone as a sterilant effectiveness
affects spores and all types of microbes
stability of ozone
not stable but is good as the residue can be removed by leaving product in chamber for a few minutes
advantage of ozone
compatibility with many materials
nosocomial infections show resistance to
AGs, quinolone, cephalosporins, extended spectrum penicillins
risk classification of patients
A B C
A has minimal risk (no underlying disease)
B has infection
C is severely immunocompromised or has severe burns or trauma
low level disinfectants - 4
alcohol, sodium hypochlorite (bleach), iodophors, phenols
high level Ds - 6
can affect spores
gluteraldehyde, h2o2 at 7.5%, ortho pthaldehyde, h2o2/peracetic acid, formaldehyde, sodium hypochlorite
is QAC high or low level D
low
are high level disinfectants sporicidal
no but at prolonged exposure time they can be and will be chemical sterilants
