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MICROBIO BIOL-160 LEC > Control of Microbial Growth > Flashcards

Control of Microbial Growth Flashcards

1
Q

defintion of STERILIZATION

A

the 100% DESTRUCTION of all LIVING MICROORGANISMS INCLUDING SPORES

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2
Q

definition of COMMERICAL STERILIZATION

A
  • 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
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3
Q

definition of DISINFECTION

A

control directed at DESTROYING MICROORGANISMS
- especially PATHOGENS
using CHEMICAL METHODS (DISINFECTANTS) and PHYSICAL METHODS

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4
Q

definition of ANTISEPSIS

A

disinfection directed at LIVING TISSUE

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5
Q

definition of DEGERMING

A

the PHYSICAL REMOVAL of MICROORGANISMS
- ex. hand washing

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6
Q

definition of SANITIZATION

A

the LOWERING NUMBER OF MICROORGANISMS to a SAFE LEVEL
- ex. dishwasher and glassware

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7
Q

definition of BACTERIOSTATIC and BACTERICIDAL

A

BACTERIOSTATIC:
STOPS BACTERIAL GROWTH–but once removed bacteria can grow again

BACTERICIDAL:
causes BACTERIAL DEATH **BIOCIDAL

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8
Q

definition of DEATH RATE

A

the calculation of DEATH UNDER STANDARDIZED CONDITIONS
- death PER MIN
- dying at CONSTANT RATE

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9
Q

what are the FACTORS that AFFECT DEATH RATE?

A
  • the NUMBER OF MICROBES
  • ENVIRONMENTAL CONDITIONS
    media
    temperature
    pH
  • TIME OF EXPOSURE
  • MICROBIAL CHARACTERISITIC
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10
Q

describe some MICRBIAL CHARACTERISITICS–what are bactericides EFFECTIVE AGAINST?

A
  • 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)
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11
Q

pseudomonas burkholderia

A

unusually RESISTANT to BACTERIOCIDES and ANTIBIOTICS

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12
Q

describe MYCOBACTERIUM

A
  • 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

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13
Q

what do we want in MICROBIAL CONTROL METHODs and what FACTORS need to be considered?

A

WANTS:
- INEXPENSIVE
- FAST-ACTING
- STABLE
- SAFE

FACTORS:
- SITE TREATED
- SUSCEPTIBILITY (how do they respond to actual ANTIMICROBIAL TREATMENT)
- ENVIRONMENTAL CONDITIONS
(TEMPERATURE)
(pH)
(PRESSURE)

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14
Q

what are our MODES of ACTION

A
  • PROTEINS DENATURATION
  • NUCLEIC ACIDS DAMAGE
  • DAMAGE to LIPIDS and PROTEINS within CELL MEMBRANE (disruption of membrane)
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15
Q

what are OUR PHYSICAL METHODS?

A

TEMPERATURE
- heat
- cold
- DESICCATION
- FILTRATION
- OSMOTIC PRESSURE
- RADIATION

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16
Q

definition of THERMAL DEATH POINT

A

the MINIMAL TEMP for complete MICROBIAL DEATH in 10 MINUTES

17
Q

definition of THERMAL DEATH TIME

A

the MINIMAL TIME for COMPLETE MICROBIAL DEATH at SET TEMP

18
Q

definition of DECIMAL REDUCTION TIME

A

time in min in which 90% of the BACTERIA is killed at a GIVEN TEMP

19
Q

what are our HEAT METHODS?

A

MOIST HEAT:
- BOILING
- AUTOCLAVE/STEAM
- PASTURIZATION

DRY HEAT:
- OVENS

20
Q

describe BOILING

A
  • 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

21
Q

describe AUTOCLAVING

A

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..

22
Q

describe PASTEURIZATION

A

MILD HEATING to KILL some FOOD BORNE PATHOGENS while NOT DAMAGING FOOD
- REDUCES NUMBER of MICROBES that REMAIN

23
Q

describe OVENS

A

used when WATER is NOT AN OPTION
- has DECREASED EFFICACY
170 C under 16 hours

24
Q

describe REFRIGERATION

A

around 0 - 7 C
- this is a BACTERIOSTATIC TECHNIQUE
- other PSYCHORPHILIC ORGANISMS can STILL SURVIVE and GROW

25
Q

describe FREEZING

A

UNDER ZERO CELSIUS
- means of SLOW FREEZING–crystals form and DISRUPT the CELLULAR STRUCTURE
- FREEZE THAW is MORE DAMAGING

26
Q

describe FILITRATION

A

FILTERING OUT MICROORGANISM out of the AIR for STERILE WORK ENVIRONMENT
- seen in OR and LAMINAR FLOW CABINETS within LAB

27
Q

describe DESICCATION

A
  • BACTEROSTATIC TACTIC
    enables NO GROWTH and REPRODUCTION–resistance to DESICCATION VARIES

*NEISSERIA GONORRHOEAE - 1 HOUR
*MYCOBACTERIUM TUB - months
*SPORES AND VIRUSES–resistant

28
Q

describe OSMOTIC PRESSURE

A

here we have HIGH CONCETRATIONS of SALT AND SUGAR–creation of a HYPERTONIC ENVIRONMENT
- water LEAVES MICROBIAL CELLS
- used for FOOD PRESERVATION
- NOT ANTIFUNGAL

29
Q

describe RADIATION and its TYPES

A

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

30
Q

context of CHEMICAL METHODS

A

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

31
Q

describe DILUTION TEST

A
  • 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
32
Q

describe DISK DILUTION METHOD

A

use of DISK FILTERS SOAKED within TESTED CHEMICAL
- use of ANTIBIOTIC DISCS to DETERMINE RESISTANCE and SENSITIVITY of BACTERIA

33
Q

describe PHENOLS

A
  • 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

34
Q

describe ALCOHOLS

A

EFFECTIVE against;
- BACTERIA
- FUNGI
- VIRUSES

NOT EFFECTIVE against;
- ENDOSPORES
- FUNGAL SPORES

  • begins to DENATURE PROTEINS and DISSOLVES LIPIDS
  • EFFECTIVE CONC: 60-70%
35
Q

describe METALS and TYPES OF METALS

A

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

36
Q

describe ALDEHYDES

A

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

37
Q

describe GASES

A

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

MICROBIO BIOL-160 LEC (21 decks)

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