Control of Microbial Growth Flashcards
decontamination/infection
-nuetralization or removal of microbes
-goal is to reduce number/impact of potentially harmful organisms
sterilization
-processing of killing all microorganisms
-sterility can be thought of as binary, its either sterile or it isnt
decimal reduction time
amount of time it takes to reduce number of microbes by a factor of 10
-depends on pH, salt concentration, moisture levels, presence of fats/sugars proteins in samples (can decrease heat penetration)
decima reduction time and food safety
pastuerization
-prevent spoilage and protect against food borne pathogens with certain foods and beverages
-heated for a specific amount of time to eliminate pathogens and to reduce spoiling agents
milk pasteruization time
-71C for 15seconds
-balances between minimal loss of food quality and safety
-not sterilization
-heat resistant lactic acid bacteria survive pastuerization and are what cayse the milk to spoil over time
autoclaves
-sterilization
-use steam to sterilize by heat
-endospores require 121 for 15mins
-water (steam) is pressureized to increase boiling temp allowing it to be 121
-high pressure steam circulated through autoclave
ultraviolet light
-damages DNA and is lethal to microbes at high enough intensities
-useful for sterilizing surfaces or aire, but poor penetrating power
ionizing radiation
improved penetrating power and is used to sterilize surgical supplies labwear and food
filtration
-passing liquids through fiters with pore size of 0.2microns is a common way to sterilize solutions
-high quality filters are very effective but not as reliable as autoclaving
-used for some applications in the lab instead of heat since heat can cause damage
how do many chemical products work (also damage human cells)
-membrane disruption, protein denaturation, oidizing agent
sterilizants
kill microbes
-formadelhyde
disinfectants
-largely for surfaces, kill many/most microbes but not all
-lysol
sanitizers
-similar to disinfectants but less harsh to human also generally less effective
-soaps
antiseptics
-kill or inhibit growth of microbes, non toxic enough to use on tissues
antimicrobial agent
chemical that kills or inhibits the growth of microbes
cidal
-agent that kill cells
-irreversible
static
-agents that do not kill but that inhibit growth
-prevent growth but microbes are not dead and can recover
lytic
-agents that kill cells and cause them to lyse
Minimum inhibitory concentration
-lowest concentration of a compound that fully inhibits microbial growth
-determined using serial dilutions of the compound
zone of inhibition
-antimicrobial activity can also be assessed using solid media combined with disks that contain compound of interest
-disk places on agar plate and diffuses
-closer disk = higher concentration of antimicrobial agent
-the size of the zone of inhibition (area of no growth) indicated suceptibility to compound
-kirby bauer test
antibiotics
-specific mechanisms to taget microbes rather than generic and non specific toxitcityes such as widely inactivating proteins or disrupting membranes
-topical antibiotics are antibiotics in creams
-other antibiotics are typically ingested and must not harm human cells
-generally a small molecule that target specific aspect
alexander fleming
-discovered penecillin from mold on a contamination plate
-also discovered lysozyme
sulfa drugs
first effective ingested Ab was protosil that inhibits folate biosynthesis (folate essential cofactor)
-not effective in test tibe only in live animals as protosil is a pro drug that must be processed by body into its active form (sulphanilamide)
