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Microbiology > Chapter 7: Controlling Microbial Growth > Flashcards

Chapter 7: Controlling Microbial Growth Flashcards

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Biology 101 flashcards
1
Q

sterilization

A

destruction/removal of microbial life from an object.
Physical processes: filtration, high temp, incineration, irradation by UV light or gamma rays
Chemical processes: ethylene oxine (used in hospitals), chrloine dioxide (decontamination of buildings), steam sterilization (microbiology)
mechanical processes: filtration

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2
Q

disinfection

A

use of chemicals (disinfectants to kill or inhibit microorganisms that cause disease
does not kill all microorganisms, usually toxic and injurious to human issues

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3
Q

sanitization

A

related to disinfection, however, sanitization only reduces the microbial population to acceptable standards
restaurants/cafeterias sanitize eating utensils to acceptable health and public standards

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4
Q

antisepsis

A

related to disinfection
chemicals used to treat or prevent infection of living tissues (still toxic)
common antiseptics: alcohol, iodine, chlorhexidine, heavy metals (silver, mercury)

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5
Q

antimicrobial agents

A

agents that kill or inhibit the growth of microorganisms (cidal or static)

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6
Q

cide antimicrobial agents

A

cide: suffix indicating agent kills organisms
* Biocide or germicide: kills microorganisms
* Virocide: inactivates viruses
* e.g. microbiocides for HIV used in spermacides
* Fungicide: kills fungi

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7
Q

static antimicrobial agents

A
  • static: agent that inhibit growth
  • Bacteriostatic agent: (inhibits) growth of bacteria
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8
Q

sepsis

A

bacterial contamination

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9
Q

asepsis

A

absence of significant contamination

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10
Q

aseptic techniques

A

methods that minimizes contamination

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11
Q

factors affecting antimicrobial effectiveness (6)

A

1) Population size: the larger populations, the longer to kill
2) Population composition: Different sensitivity to antimicrobials
3) Concentration or intensity: The higher the conc., the greater the effect
4) Time of exposure longer exposure, more organisms killed
5) Environment conditions: High temperatures (more killing), Organic material (decreases killing) E.g. Sewage, biofilms
6) Microbial characteristics: Spores more resistant than vegetative cells

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12
Q

what is more resistant: gram negative or gram postive? why?

A

gram negative because they have LPS rich outer membrant to protect against chemical biocides

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13
Q

what is more resistant: acid fast or nonacid fast?

A

acid fast because they have a thick, waxy layer that makes them resistant

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14
Q

what is more resistant: endospore or vegetative?

A

endospore

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15
Q

what is more resistant: naked virus or enveloped?

A

naked virus

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16
Q

what is more resistant: cyst or trophozoite stages of protozoans?

A

cyst is more resistant

17
Q

physical control methods

A

heat: dry and moist

18
Q

what is an autoclave?

A

steam sterilizer that operates like a pressure cooker
- operates in a cycle
-saturated chamber with steam
- raises the temp to 121 degrees
-applies pressure 15 psi for 15 mins
-steam condenses on objects

19
Q

pasteurization

A

reduces number of pathogens but does not change the taste!
considered a disinfectant

20
Q

what are the 3 different ways that milk can be pasteurized?

A

1) Low-temperature hold (LTH)
62.8°C for 30 minutes
used when you dont have a lot of milk to pasteurize
2) High-temperature short-term (HTST):
72°C for 15 seconds
most commonly used when you have lots of milk and it is usually the milk you buy
3) Ultra-high temperature (UHT):
Process (5 sec cycle 74oC to 140°C to 74oC)
packaged in open shelves and doesnt need to be refrigerated- sweet milk

21
Q

filtration

A

can reduce microbial population in liquids by sterilizing heat sensitive materials and recudes microbial populations in the air

22
Q

2 types of filtration

A

1) depth filtering
2) membrane filters- 0.1mm thick, pore sizes from 0.2 micrometers (bacteria will not be able to pass through these pores)

23
Q

refrigeration is _______

A

bacteriostatic where most pathogens do not grow except listeria monocytes

24
Q

Non ionizing radiation

A

UV light- not penetrating, can damage eyes and DNA, germicidal lamps for vaccine disinfection

25
Q

ionizing radiation

A

gamma rays, x rays, or high energy electron beams, cause mutations and death, low ionizing radiation- used on spices, certain meats and vegetables, high energy radiation- used to sterilize medical supplies

26
Q

limiting water

A

desiccation: bacteriostatic: lyphilization used to preserve cultures (removes water from the environment)
osmotic pressure- high con of salt or sugar removes water from the environment and destroys microorganisms

27
Q

disc dilution methods

A

-inoculate bacteria on nutrient agar plates
-place filter discs impregnated with disinfectant on plates and incubate
-measure zones of inhibition- the larger the diameter, the more effective the antibiotic is

28
Q

phenols

A

-originally used by Joseph Lister
- used as chemical disinfectants
-can be identified by benzene ring with OH attached to it

29
Q

lysol phenol

A

Mixture of phenols used as general disinfectant

30
Q

hexachlorophene phenol

A

Excellent skin disinfectant
Effective against S. aureus
But is neurotoxic in rats

31
Q

triclosan phenol

A

Used in antibacterial soaps and toothpaste
Banned in soaps in US in 2017
Broad spectrum of activity

32
Q

Chlorhexidine

A

Disinfectant (member of biguanides)
Widely used by dentists
Also used as skin antiseptic
Low toxicity
Used on skin and mucous membranes

33
Q

halogens

A

disinfections: split into iodine, chlorine, chlorine gas, chloramines

34
Q

iodine halogen

A

Tincture (iodine+alcohol)
Iodophors (iodine+organic carrier)
Betadine® and Isodine®, Wescodyne
Stain skin and garments
Effect agains all bacteria, spores, fungus and viruses

35
Q

chlorine halogens

A

used to disinfect water supplies (active ingredient: Hypochlorous acid)
Effective against wide range of microbes
Disadvantage:
Corrosive
Inactivated by organic matter
Forms chlorine disinfection by-products (DBPs) linked to bladder cancer

36
Q

chlorine gas

A

can form bleach (hypochlorite ions) in water

37
Q

chloramines

A

chlorine and ammonia

38
Q

alcohols

A

disinfectants
split into ethanol or isopropanol
denature proteins and damage cell membrane
used to clean skin

Microbiology (11 decks)

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