MICROBIAL CONTROL Flashcards
bacteria are preparing to divide and period of adjustment in the new environment
lag phase
bacteria number increases logarithmucally or undergoes rapid cell dividion
log / exponential phase
nutrients are becoming limited but the number of bacteria remains constant / state of equilibrium
stationary phase
nonviable bacteria exceed the number of viable cells
death phase
cells are __ % water
70-95 %
which microbes survive lack of water for lung durations
bacterial endospores and protozoan cysts
pH of acidophiles
< 5.4
pH of alkalinophiles
7 - 11.5
pH of neutrophiles
5.4 - 8.5
most organisms grow best under ideas conditions of osmotic pressure, which is determined by ___
salt concentration
destruction of all viable microorganisms
sterilization
destruction or removal of pathogens from nonliving objects physical or chemical methods
disinfection
free of viable pathogenic microorganisms
asepsis
prevention of infection by inhibiting the growth of pathogens
antisepsis
growth inhibiting agent
antiseptic
mechanical removal of most microbes from animate or inanimate surface
decontamination
soap or detergent used
sanitizer
removal or reduction of microorganisms from the skin
degerming / degermination
disinfectant that kill microbes, can be used on inanimate materials or on living tissue, but cannot kill resistant microbes
germicide
chemical that inhibits the growth and reproduction of bacteria on tissues or on objects
bacteristatic / bacteriostatic agent
inhibition of bacterial growth
bacteriostasis
chemical that destroys bacteria except for endospores
bactericide
substance capable of killing bacteria
bactericidal
enumerate the effects of antimicrobial agents on cellular structure
- damage to cell wall integrity
- alteration of membrane permeability
- damage to protein and nucleic acid
most practical, efficient and inexpensive method of sterilization of inanimate objects / materials
heat
microbes with the greatest resistance to heat
bacterial endospores
microbes with the least resistance to heat
vegetative state of bacteria and fungi
- using pressurized steam
- 15 psi of pressure
- 121 C temp for 15 minutes
USE: sterilize culture media, surgical instruments, and linens
autoclaving
- inside a chamber
- free flowing stream for 30-60 mins
- 24 hours incubation
USES: for heat sensitive culture media, canned foods
non-pressurized steam / intermittent sterilization / tyndallization
- heat applied to liquids
- retains flavor and food value
USES: destroys pathogen in food: milk, yogurt, beer, etc.
pasteurization
- heating objects in water at 100 C
- achieves disinfection, not sterilization
USES: drinking water, utensisl, food prep, materials for babies, clothing
boiling
- used to destroy contaminating bacteria in vaccine prep
- water bath at 60 C
vaccine bath
- inactivate bacteria ocntaminating serum prep
- heating at 56 C for successive days
serum bath
- sterilize inoculating loops, dehydrates the cell, denatures proteins, oxidizes cell
USES: inoculation in the lab, processing culture media
direct flaming
- complete destruction and disposal of infectious materials
USES: infectious waste disposal
incineration
- oven at 180 C for 2-4 hours
USES: sterilize glassware, metal instruments, powders, and oils
hot air sterilization
- bacteriostatic
- slows the growth of most microorganisms
USES: preserving foods, drugs, and microbal culture
refrigeration
- culutres are quick-frozen at -50 to -95 C
USES: preserving foods, drugs, and microbe culture
deep freezing