sepsis
bacterial contamination
asepsis
absence of significant contamination
aseptic surgery technique
prevent the microbial contamination of wounds
sterilization
removing and destroying all microbial life (not including viruses)
commercial sterilization
killing C. botulinum endospores from canned goods
disinfection
destroying harmful microorganisms
antisepsis
destroying harmful microorganisms from living tissue
degerming
the mechanical removal of microbes from a limited area
sanitization
lowering microbial counts on eating utensils to safe levels
biocide (germicide)
treatments that kill microbes
bacteriostasis
inhibiting growth , not killing, microbes
chemotherapy
use of chemicals to kill or inhibit growth of microorganisms within host tissue
-cidal or -static
antimicrobial agents can be
-cidal
means to kill; pathogens and many nonpathogens but not necessarily endospores
-static
inhibits growth
rate of microbial death
microorganisms are not killed instantly; die at a constant rate
are not
microorganisms are or are not killed instantly
constant
microorganisms die at a ______ rate
population size, population composition, concentration or intensity of an antimicrobial agent, duration of exposure, temperature, local environment
conditions influencing the effectiveness of antimicrobial agent activity
population size
larger populations x smaller populations
position composition
microorganisms x sensitivity to antimicrobial agents
concentration or intensity of an antimicrobial agent
higher concentrations x lower concentrations
duration of exposure
longer exposure --> more organisms killed
higher
_____ temperatures usually increase amount of killing
local environment
many factors (pH, viscosity, and concentration of organic matter) can profoundly impact effectiveness
biofilms
organisms in ____ are physically altered and less susceptible to many antimicrobial agents
alteration of membrane permeability, damage to proteins (enzymes), damage to nucleic acids
actions of microbial control agents
alteration of membrane permeability
damage to the lipids or proteins of the plasma membrane causes cellular content to leak into the surrounding medium
damage to proteins (enzymes)
denaturation of proteins due to heat or chemicals
damage to nucleic acids
by heat, radiation, or chemicals
heat, filtration, low temperatures, high pressure, desiccation, osmotic pressure, radiation
physical control methods
denatures
heat ____ enzymes
varies
heat resistance ___ among different microbes
thermal death point (TDP)
lowest temperature at which all cells in a liquid culture are killed in 10 minutes
thermal death time (TDT)
minimal time for all bacteria in a liquid culture to be killed at a particular temperature
TDP and TDT
used as guidelines to determine treatment to kill bacterial population
decimal reduction time (DRT)
minutes to kill 90% of a population at a given temperature
moist heat sterilization
denatures proteins, degrades nucleic acids, and disrupts membranes
moist heat sterilization
boiling, free-flowing steam, autoclave
free-flowing steam
destroys viruses, fungi and bacteria but will not destroy all viruses or endospores and does not sterilize
autoclave
steam under pressure
121 C
autoclave temperature at 15 psi for 15 minutes
all
autoclave kills ____ organisms and endospores
contact the item's surface
steam in the autoclave must
true
T/ F: autoclave sterilizes
false
T/ F: free-flowing steam sterilizes
longer
large containers require ____ sterilization times
test strips
used to indicate sterility
pasteurization
reduces spoilage organisms and pathogens
72 C for 15 sec
high-temperature short-time (HTST)
140 C for 4 sec
ultra-high-temperature (UHT)
63 C
temperature of pasteurization for 30 minutes
pasteurization
used for milk, beer, and other beverages
thermoduric
what organisms survive pasteurization?
less, higher, longer
dry heat sterilization is ____ effective than moist heat sterilization, requiring ____ temperatures and ____ exposure times
dry heat sterilization
oxidizes cell constituents and denatures proteins
dry heat sterilization
flaming, incineration, hot-air sterilization
bench top incinerators
used to sterilize inoculating loops used in microbiology laboratories
filtration
passage of substance through a screen like material
filtration
used for heat-sensitive materials