Control of Microbial Growth Flashcards
defintion of STERILIZATION
the 100% DESTRUCTION of all LIVING MICROORGANISMS INCLUDING SPORES
definition of COMMERICAL STERILIZATION
- only ERADICATES SPOLIAGE and PATHOGENIC MICROORGANISMS
ex. LIMITED HEAT TREATMENT–food will lose taste and texture
ex. for canned foods–have treated temp and conditions to remove C. BOTULINUM SPORES but not ALL SPORES
definition of DISINFECTION
control directed at DESTROYING MICROORGANISMS
- especially PATHOGENS
using CHEMICAL METHODS (DISINFECTANTS) and PHYSICAL METHODS
definition of ANTISEPSIS
disinfection directed at LIVING TISSUE
definition of DEGERMING
the PHYSICAL REMOVAL of MICROORGANISMS
- ex. hand washing
definition of SANITIZATION
the LOWERING NUMBER OF MICROORGANISMS to a SAFE LEVEL
- ex. dishwasher and glassware
definition of BACTERIOSTATIC and BACTERICIDAL
BACTERIOSTATIC:
STOPS BACTERIAL GROWTH–but once removed bacteria can grow again
BACTERICIDAL:
causes BACTERIAL DEATH **BIOCIDAL
definition of DEATH RATE
the calculation of DEATH UNDER STANDARDIZED CONDITIONS
- death PER MIN
- dying at CONSTANT RATE
what are the FACTORS that AFFECT DEATH RATE?
- the NUMBER OF MICROBES
- ENVIRONMENTAL CONDITIONS
media
temperature
pH - TIME OF EXPOSURE
- MICROBIAL CHARACTERISITIC
describe some MICRBIAL CHARACTERISITICS–what are bactericides EFFECTIVE AGAINST?
- more EFFECTIVE AGAINST GRAM POSITIVE BACTERIA
- resistance of GRAM - due to LIPOPOLYSACCHARIDES in OUTER MEMBRANE–able to PUMP STUFF OUT through PORINS (selectively allows molecules into CELL)
pseudomonas burkholderia
unusually RESISTANT to BACTERIOCIDES and ANTIBIOTICS
describe MYCOBACTERIUM
- very RESISTANT to a LOT OF CHEMICAL BIOCIDES
- has a WAXY LIPID RICH LAYER within CELL WALL–makes them ACID FAST and gives PROTECTION
**M. TUBERCULOSIS–causative agent of TB
what do we want in MICROBIAL CONTROL METHODs and what FACTORS need to be considered?
WANTS:
- INEXPENSIVE
- FAST-ACTING
- STABLE
- SAFE
FACTORS:
- SITE TREATED
- SUSCEPTIBILITY (how do they respond to actual ANTIMICROBIAL TREATMENT)
- ENVIRONMENTAL CONDITIONS
(TEMPERATURE)
(pH)
(PRESSURE)
what are our MODES of ACTION
- PROTEINS DENATURATION
- NUCLEIC ACIDS DAMAGE
- DAMAGE to LIPIDS and PROTEINS within CELL MEMBRANE (disruption of membrane)
what are OUR PHYSICAL METHODS?
TEMPERATURE
- heat
- cold
- DESICCATION
- FILTRATION
- OSMOTIC PRESSURE
- RADIATION
definition of THERMAL DEATH POINT
the MINIMAL TEMP for complete MICROBIAL DEATH in 10 MINUTES
definition of THERMAL DEATH TIME
the MINIMAL TIME for COMPLETE MICROBIAL DEATH at SET TEMP
definition of DECIMAL REDUCTION TIME
time in min in which 90% of the BACTERIA is killed at a GIVEN TEMP
what are our HEAT METHODS?
MOIST HEAT:
- BOILING
- AUTOCLAVE/STEAM
- PASTURIZATION
DRY HEAT:
- OVENS
describe BOILING
- have 100 C per 10 min
begins to kill VEGETATIVE CELLS (such as bacteria, fungi, viruses, protozoa)
**does NOT KILL ENDOSPORES–can survive OVER 20 HOURS of BOILING
**recommended for houseware and routine utensils
describe AUTOCLAVING
steaming over 100 C–INCREASE OF TEMP UNDER PRESSURE
- 15 PSI
- 121 C
- around 20-30 min
**CAN KILL ALL THINGS EXCEPT PRIONS
- can help in terms of STERILIZATION of BACTERIAL MEDIA, instruments, solutions etc..
describe PASTEURIZATION
MILD HEATING to KILL some FOOD BORNE PATHOGENS while NOT DAMAGING FOOD
- REDUCES NUMBER of MICROBES that REMAIN
describe OVENS
used when WATER is NOT AN OPTION
- has DECREASED EFFICACY
170 C under 16 hours
describe REFRIGERATION
around 0 - 7 C
- this is a BACTERIOSTATIC TECHNIQUE
- other PSYCHORPHILIC ORGANISMS can STILL SURVIVE and GROW
describe FREEZING
UNDER ZERO CELSIUS
- means of SLOW FREEZING–crystals form and DISRUPT the CELLULAR STRUCTURE
- FREEZE THAW is MORE DAMAGING
describe FILITRATION
FILTERING OUT MICROORGANISM out of the AIR for STERILE WORK ENVIRONMENT
- seen in OR and LAMINAR FLOW CABINETS within LAB
describe DESICCATION
- BACTEROSTATIC TACTIC
enables NO GROWTH and REPRODUCTION–resistance to DESICCATION VARIES
*NEISSERIA GONORRHOEAE - 1 HOUR
*MYCOBACTERIUM TUB - months
*SPORES AND VIRUSES–resistant
describe OSMOTIC PRESSURE
here we have HIGH CONCETRATIONS of SALT AND SUGAR–creation of a HYPERTONIC ENVIRONMENT
- water LEAVES MICROBIAL CELLS
- used for FOOD PRESERVATION
- NOT ANTIFUNGAL
describe RADIATION and its TYPES
WAVES:
- WAVELENGTH BAED (gamma rays, x rays, UV)
IONIZING RADIATION;
- used to TREAT FOOD
- seen in PHARM, DENTAL , MEDICAL SUPPLIES
NONIONIZING UV RADIATION:
- has STRONG BACTERICIDAL EFFECT
- DAMAGES DNA
- kills ORGANISMS in AIR
- HARMFUL TO SKIN and EYES
context of CHEMICAL METHODS
seen and used on LIVING TISSUE an INANIMATE OBJECTS
- REDUCES NUMBER OF MICROORGANISMS
- NO SINGLE DISINFECTANT is GOOD FOR ALL THINGS
(consider LABEL and CONCENTRATION + NATURE OF MATERIAL BEING DISINFECTED
describe DILUTION TEST
- metal or glass BEADS dipped in BACTERIA
- dried cultures placed in DISINFECTANT for 10 MINUTES at 20 C
- rings are transferred to see if BACTERIA SURVIVED TREATMENT
describe DISK DILUTION METHOD
use of DISK FILTERS SOAKED within TESTED CHEMICAL
- use of ANTIBIOTIC DISCS to DETERMINE RESISTANCE and SENSITIVITY of BACTERIA
describe PHENOLS
- EFFECTIVE in DENSE ORGANIC MATERIAL
- DENATURES PROTEINS and DISRUPTS LIPID MEMBRANES
- ACTIVE for a LONG TIME
- used in THROAT SPRAYS
CONS:
- CORROSIVE (during HIGH CONC.)
- IRRITANT
- MUTATIVE
describe ALCOHOLS
EFFECTIVE against;
- BACTERIA
- FUNGI
- VIRUSES
NOT EFFECTIVE against;
- ENDOSPORES
- FUNGAL SPORES
- begins to DENATURE PROTEINS and DISSOLVES LIPIDS
- EFFECTIVE CONC: 60-70%
describe METALS and TYPES OF METALS
FUNCTION:
- works by DENATURING PROTEINS
AG (SILVER):
- 1% SILVER NITRATE–eyes of newborn to PROTECT FROM INFECTION
HG (MERCURY):
- MERCURIC CHLORIDE (VERY TOXIC)
- used as TOPICAL ANTISEPTIC (MERBROMIN)
CU (COPPER):
- WATER-BASED TREATMENTS
- seen in Xgel HAND SANITIZERS
describe ALDEHYDES
FUNCTION:
- DENATURES PROTEINS
- DAMAGES DNA + RNA
FORMALDEHYDE:
- use of FORMALIN (37%) preserves BIOLOGICAL SAMPLIES
- IRRITANT and CARCINOGENIC–not used on living tissue
GLUTERALDEHYDE:
- LESS IRRITATING and MORE EFFECTIVE
- seen in DISINFECTION within HOSPITALS
- 2% SOLUTION turns BACTERCIDAL within 10 min
- 3-4 hours; able to kill SPORES
describe GASES
chemicals that in GASEOUD FORM STERILIZE
- must be within CLOSED CHAMBER
- LOW EFFICACY + TOXIC and EXPLOSIVE
ETHYLENE OXIDE:
used for HEAT SENSITIVE EQUIPMENT such as flexible fibers and endoscopes
CHLORINE OXIDE:
anthrax
