IC5 Flashcards
what are pyrogens
substances that induce fever when injected into mammals
what are the types of pyrogens
1) LPS from gram -ve bacteria
2) microbial substances: basically the microorganisms
3) non microbial: rubber, microscopic plastic, metal compound in elastomer
types of animal based pyrogen test - rabbit pyrogen test (RPT) - general
- measure rise in rabbit temp after IV injection of tested product
- qualitative
types of animal based pyrogen test - rabbit pyrogen test (RPT) - disadvantages
1) low sensitivity
2) development of pyrogen tolerance after repeated injection
3) stress from rabbit when performing assay
4) POOR RABBITS
types of animal based pyrogen test - bacterial endotoxin test (BET) or limulus amoebocyte lysate (LAL) test
- horseshoe crab
- high sensitivity (quantification)
- can’t test for non endotoxin pyrogens
types of in vitro pyrogen test - monocyte activation test (MAT) - how it works
IF PYROGEN PRESENT:
monocyte activated -> produce inflamamtory molecule & cytokines for febrile reaction -> detect cytokines using ELISA for specific antibodies & enzymatic colour reaction
types of in vitro pyrogen test - recombinant factor C (rFC)
- factor C react w endotoxin + marker = quantifiable, fluorescent end product
- similar to BET/LAL but no horseshoe crab blood
types of culture media used for sterility testing
1) fluid thioglycolate medium (FTM)
- anaerobic & some aerobic bacteria
2) soybean casein digest medium (SCDM)
- fungi & aerobic bacteria
3) sabouraud dextrose agar (SDA)
- yeast
how many days are samples incubated for in culture medium and why so long
14 days, not every bacteria grow at the same rate
types of sterility testing methods - j list down all
1) membrane filtration
2) direct inoculation
3) direct transfer
4) product flush
membrane filtration sterility testing - process
passed through 0.45 micrometer membrane in filtration canister & culture medium added for incubation
membrane filtration sterility testing - sensitivity
HIGH
- whole sample passed through single filter
membrane filtration sterility testing - advantages
can wash away components that cause turbidity/inhibit growth (abx, preservative)
membrane filtration sterility testing - most probable number (MPN)
estimate viable numbers of bacteria in sample by inoculating broth in 10-fold dilutions based on principle of extinction dilution
direct inoculation sterility testing - process
small vol of sample removed aseptically from sample -> inoculated directly into suitable vol of growth medium -> incubation
direct inoculation sterility testing - sensitivity
LOW
- only small vol inoculated into culture medium
direct inoculation sterility testing - disadvnatages
if sample cloudy/turbid after inoculation: tough to detect turbidity from microbial growth at end of incubation period
direct inoculation sterility testing - testing sterility of antimicrobial product
need to neutralise first so microorganism can growth
direct transfer sterility testing - what is it used for
medical device
direct transfer sterility testing - how does it work
device in direct contact w test media during incubation -> microorganism in/on device grow & proliferate
product flush sterility testing - what is it used for
medical devices w hollow tubes where fluid pathway is labelled as sterile
product flush sterility testing - how does it work
product lumen flushed w rinsing fluid -> elute membrane filtered -> placed in suitable media for incubation
what are the disadvantages of sterility testing methods
1) lengthy process
2) sample size problems
3) costly
list of all the sterilisation methods
1) moist heat
2) dry heat
3) chemical
- ethylene oxide
- peracetic acid
- gas plasma
4) gamma radiation
5) ozone
moist heat sterilisation - process
expose each item to direct steam contact at required temperature & pressure for specified time
moist heat sterilisation - MOA
destroy microorganism by irreversible coagulation & denaturation of enzymes & structural proteins
moist heat sterilisation - parameters
1) steam
2) pressure (for high temp)
3) high temperature (121 - 132 deg celc)
moist heat sterilisation - D-value
- time to reduce surviving population by 90% or 1logD
- used for direct comparison of microorganism heat resistance.,…dfdsfsdf
moist heat sterilisation - F-concept
- equivalent time that monitored object is exposed to desired temperature
- basically from turning on the machine to when object reach sterilisation temperature
dry heat sterilisation - what is it used on
1) materials damaged by moist heat
2) materials impenetrable to moist heat (powder, petroleum, sharp instrument)
dry heat sterilisation - advantages
1) easier to operate & maintain
2) slow rate of heat penetration
dry heat sterilisation - types
1) static-air type
- slower in heating (longer time to reach sterilising temp)
- less uniform in temperature control throughout chamber
2) forced-air type
- circulate heated air throughout chamber = rapid transfer of energy from air to instrument
dry heat sterilisation - parameters
> 220 deg celc
chemical sterilisation - ethylene oxide (ETO) - how it works
alkylating agent, attack protein, nucleic acid, other compounds
chemical sterilisation - ethylene oxide (ETO) - advantages
- works on several materials
- well tolerated
- residue eliminated w proper aeration
chemical sterilisation - ethylene oxide (ETO) - limitations
- flammable & explosive
- lots of side effects
- carcinogenic
chemical sterilisation - paracetic acid - how it works
highly biocidal oxidiser that still works in organic soil
chemical sterilisation - paracetic acid - uses
endoscopic tube
chemical sterilisation - paracetic acid - parameters for inactivation of different types of microorganism dfjskdjfkasj IDK IF IMPT
1) gram pos, gram -ve, fungi, yeast
- < 5 mins at < 100ppm
2) presence of organic matter
- 200-500 ppm
3) virus
12-2250 ppm
4) bacterial spore
15s-30s, 500-10k ppm
chemical sterilisation - gas plasma - production
deep vacuum -> radio freq/microwave energy -> excite gas molecules -> produce charged particles (free radicals) within plasma field -> interact w essential cell component -> disurpt microorganism metabolism
chemical sterilisation - gas plasma - parameters
1) deep vacuum
2) 37-44 deg celc
3) 75 mins
chemical sterilisation - gas plasma - MOA
h2o2 inactivate broad range of microorganism from surfaces as well
chemical sterilisation - gas plasma - advantages
- by products non toxic (X need aeration)
- sterilised material handled safety
gamma radiation - parameters
MAN I REALLY DK IF THIS IS IMPORTANT DJHFAKJSD
- cobalt 60, cesium 137, electron accelerator
- low temperature
gamma radiation - general
1) low penetration, high dose rate
2) used for medical product & packaging material
gamma radiation - limitations
deleterious effect on patient care equipment
- induced oxidation in polyethylene
- delamination/cracking in polyethylene knee bearings
ozone - production
O2 oxidised -> 2 monoatomic molecules (O) -> collide w O2 -> ozone (O3)
advantages of ozone
- powerful oxidant that destroy microorganism
- compatible w wide range of materials
disadvantages of ozone
highly unstable
