MICROBIAL CONTROL Flashcards
refers to microbial contamination
SEPSIS
the absence of significant contamination
ASEPSIS
Killing C. botulinum endospores
COMMERCIAL STERILIZATION
Removal of pathogens
DISINFECTION
Removal of pathogens from living tissue
ANTISEPSIS
Lower microbial counts on eating utensils
SANITIZATION
Kills microbes
BIOCIDE/GERMICIDE
Inhibiting, not killing microbes
BACTERIOSTASIS
Kills bacteria
BACTERIOCIDAL
EFFECTIVENESS OF ANTIMICROBIAL TREATMENT
DEPENDS ON:
- Number of microbes
- Environment
- Time of exposure
- Microbial characteristics
- Condition of microbes
T or F
high population = shorter time for
healing
False
-longer time for healing
MECHANISM OF ACTION OF ANTIMICROBIAL
CONTROL AGENTS
CONTROL AGENTS • Alteration of membrane permeability • Damage to proteins • Damage to nucleic acid • Interfere with metabolic pathways
-very commonly used physical method of microbial control
Heat
Time to kill all cells in a culture at a
given temperature
THERMAL DEATH TIME (TDT)
Lowest temperature at which all cells in
a culture are killed at a given time
THERMAL DEATH POINT (TDP)
type of heat which denatures proteins
Moist heat
Equivalent treatments for pasteurization
● 63C for 30 mins.
● High-temperature short time: 72C for 15 secs.
● Ultra-high temperature: 140C for <1 sec
type of heat which kills by oxidation
○ Flaming
○ Incineration
○ Hot-air sterilization
Equivalent treatments for dry heat
Hot air: 170C, 2hrs
Autoclave: 121C, 15 min
● removes microbes
● for materials not conducive to be subjected in high
temperatures
Filtration
Examples of techniques which uses LOW TEMPERATURE as microbial control
● Refrigeration
● Deep freezing
● Lyophilization
● prevents metabolism
● drying and removing moisture
DESICCATION
causes Plasmolysis
OSMOTIC PRESSURE
Electromagnetic spectrum, shorter wavelength
means great energy and can penetrate further
Radiation
IONIZING RADIATION:
Xrays, gamma
rays, electron beams
NON-IONIZING RADIATION:
UV
is derived from radurization,
combining “radiation” with the stem of
“durus”, the Latin word for hard, lasting
Radura
Often chemical methods are compared to
_______
- grandfather of all chemicals used for microbial control
PHENOL
Phenol coefficient:
MORE EFFECTIVE THAN PHENOL:
> 1
LESS EFFECTIVE THAN PHENOL:
<1
PRINCIPLES OF EFFECTIVE DISINFECTION
● Concentration of disinfectant
● Organic matter
● pH
● Time
Disks of filter paper are soaked with
various chemicals and placed on an
inoculated agar plate
Disk Diffusion Method
T or F
In disk diffusion method, The greater the zone of
inhibition the better
True
Technique in which containers holding
identical volumes of broth with antimicrobial
solution in incrementally (usually
geometrically) increasing concentrations are
inoculated with a known number of bacteria.
Broth Dilution
carbolic acid
PHENOL
The MOA of Bisphenols
Disrupts plasma membranes
Example of biguanides
chlorhexidine
Forms bleach (hypochlorous acid) when added to water.
Chlorine
● More reactive, more germicidal
● Alters protein synthesis and membranes
Iodine
Iodine solution with alcohol
Tincture of iodine