Control of microorganisms Flashcards
what is the D value
The value that reduces the the population by 1 log (90%)
what is an autoclave
An autoclave kills bacteria by protein denaturation
-prions cannot be destroyed unless you use an oxidizing agent
three major ways of killing bacteria
- by damaging the plasma membrane
- denature proteins
- strong oxidizing agent
what temperature and pressure allows you to destroy all endospores
15 psi and 121 C
what is pasteurization
designed to protect public health and destroy heat resistant and vegetative cells ex: (Q fever) *not endospores we dont know about viruses tho
what does shelf life reflect
the number of microorganisms left in the dairy product
50% of flies harbor what kind of bacteria
E. coli
what kind of organism gets past the filter sterilization
viruses (only bacterial free
what kind of radiation is bactericidal
gamma rays
what kind of light can kill microorganism
UV light (with close contact) by causing the cell to form lethal thymine dimers
auto calving has a hard time killing what kind of gram bacteria?
lipopolysaccaride (will survive autoclaving)
gram negative
is moist heat or dry heat more effective
moist heat because of hydrogen bonding
what is lypophilization
does not kill bacteria
- decreased chemical reactions and possible changes in proteins
what does deep freezing do to bacteria
kills 90% of bacteria
how does desicccation work
by disrupting metabolism
how does ionization kill bacteria
destruction of DNA (used to sterilize pharmaceuticals and medical and dental supplies
what was the first disinfectant used
phenol
what is a phenol coefficient
you compare sterilization techniques to phenol using salmonella
-if you wanna test a burning unit: pseudeumonus ariginosa (used for burn patients)
- for babies you use staphacucus arius
what do we use instead of the phenol coefficient
use dilution method
what kind of sterilization technique causes brain damage
wash w hexochlorophine
what is triclosan
a bisphenol that is a disinfectant or biocide
can heavy metals inhibit bacterial growth
yes by denaturing proteins
all heavy metals have anti-bacteria action
(Mercury is toxic and so is sillinuim)
disinfectant against gram positive and negative compounds
ammonium ion and benzalkonium chloride
- damages membranes
- used in the food industry for cleaning and disinfecting
what is cetylpyridinium chloride
a quaternary ammonium salt antiseptic
what is an example of an anionic detergent
sodium laural solphate or sodium dodecyl
- inhibits gram positives but not negatives
- can be used as a selective agent
what do alcohols do to bacteria
- damage membranes
- denature proteins
- used for cleansing in intervenous blood testing
- 70% of alcohol is more effective than higher percentages
how do halogens kill bacteria
chlorine, bromine, fluorine, and iodine
- of the halogens Iodine is best because it denatures proteins by iodines the tyrosine residue
what is chlorination
forms hypochloris acid which is a very strong oxidizing agent
what are the alkylating agents
- formaldehyde
- glutaraldehyde: used in hospitals in alkaline solution which is sporicidal (CIDEX)
- ethylene oxide
- tend to be sporicidal
what does ethylene oxide react with
amino groups of proteins and adds carbons to amio groups
decreasing order of resistance of microorganisms to chemical biocides
-Most resistant
1. prions
2. endospores of bacteria
3. mycobacteria: bc of waxy material
4. cysts of protozoa
5. vegetative protozoa
6. gram-negative bacteria: because of the outer membrane
7. fungi
8. viruses without envelopes
9. gram-positive bacteria
10. viruses with lipid envelopes
-Least resistant
how well does glutaraldehyde kill endospores and mycobacteria
endospores: fair
mycobacteria: good
how does phenol kill
disruption of plasma membrane and denaturation of enzymes
what kind of toxins do gram positive bacteria produce
exotoxins
what kind of toxins do gram negative bacteria produce
endotoxins and exotoxins
cell wall disruption by lysozymes in gram negative and positive bacteria
high in gram positive
low in gram negative
inhibition by basic dyes in gram negative and positive bacteria
- gram-positive: high
- gram-negative: low
susceptibility to anionic detergents in gram negative and positive bacteria
- gram positive: high
-gram negative: kow
resistance to dying in gram negative and positive bacteria
gram negative: low
gram positive: high
net result of embden-myerhof pathway
2 atp
2 nadh
Memorize these antiseptic moleccules they will be on the test
