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Microbiology Unit 2 > Chemical & Physical Methods of Control (BE #3) > Flashcards

Chemical & Physical Methods of Control (BE #3) Flashcards

1
Q

disinfectant

A
  • reduces the # of pathogens to a level that poses no danger
  • used on inanimate objects
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2
Q

antiseptic

A
  • kills microbes or inhibits growth

- used on skin or living tissue

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3
Q

microbiocidal

A

treatment that kills molecules

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4
Q

microbiostatic

A

treatment that inhibits, rather than kills, microbes

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5
Q

sterilization

A

destroys all microbial life

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6
Q

commercial sterilization

A

food subjected to just enough heat to destroy Clostridium botulinum spores

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7
Q

2 advantages to using heat to control microbes

A
  • simple

- inexpensive

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8
Q

What is the mode of action of heat?

A

denatures proteins

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9
Q

What is disadvantage to boiling?

A

doesn’t kill thermophiles or endospores; can change the flavor of some foods

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10
Q

Conditions for autoclaving

A

15-20 min, 15 psi, 121 degrees C

  • the pressure raises the temp to above boiling
  • disadvantage - can’t use with heat sensitive materials
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11
Q

What is the advantage of pasteurization?

A

doesn’t change the taste/appearance of food

  • used in dairy products, wine, beer, “egg beaters”
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12
Q

What is the effect of using cold to control microbes?

A

microbiostatic - does not sterilize

MOA - slows down metabolic rate

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13
Q

2 types of radiation that kill bacteria & their mode of action

A

nonionizing (UV) & ionizing (x-rays, gamma rays)

MOA - mutates DNA

Sterilizes

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14
Q

What are the disadvantages of using UV light?

A

only kills on surfaces (doesn’t penetrate) & can be harmful to humans

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15
Q

2 types of ionizing radiation

Disadvantage to using this type?

How is it being used?

A

X-rays
gamma rays
MOA - strip electrons from atoms, which causes free radicals to form that damage other molecules in the cell, such as DNA

technically complex

meat, produce, grains, spices, poultry

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16
Q

Why is filtration replacing pasteurization in some cases?

A

causes even less damage to heat sensitive materials.

Used with antibiotics, beer

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17
Q

What are some microorganisms that can pass through a filter?

A
  1. Mycoplasma - no cell wall so can squeeze through small spaces
  2. spirochetes - corkscrew their way through small holes
  3. viruses - too small to stop
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18
Q

What is lyophilization?

A

freeze drying - materials are frozen & then the ice is turned to a gas.

Advantage - avoids chemical changes caused by heat drying
MOA - slows down metabolic rate;
Disadvantage - expensive

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19
Q

MOA of using high concentrations of salt or sugar?

A

creates a hypertonic environment & “sucks” the water out of bacterial cells

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20
Q

2 test organisms traditionally used to test germicides

A

Salmonella typhi

Staphylococcus aureus

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21
Q

disadvantage to using alcohol

A

evaporates quickly
doesn’t kill endospores
not good for wound treatment (causes coagulation of proteins, under which microbes can grow)

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22
Q

why is Staphylococcus relatively resistant to hydrogen peroxide (H2O2)?

A

Staph produces catalase & peroxidase, which H2O2 reacts with and turns to H2O & O2.

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23
Q

What is MOA of surfactants?

A

Penetrates oily substances in water & breaks them apart into small droplets that become coated with surfactant molecules. The hydrophobic end of the surfactant sticks into the droplets & the hydrophilic end is attracted to the water. The result is an emulsion, a fine suspension of oily droplets in water, which can now be rinsed away.

24
Q

Advantage & disadvantage to using alkylating agents

A

advantage - they sterilize

disadvantage - carcinogenic

25
Q

2 chemical preservatives added to commercially prepared foods

A
  1. calcium propionate
  2. sorbic acid
  3. sodium benzoate
  4. sodium nitrate (& nitrite)
26
Q

why is chloramine considered more effective than chlorine for the disinfection of drinking water?

A

it’s more stable & doesn’t react with organic material (blood, vomit)

27
Q

why would alcohol gel be preferred to antimicrobial soap for hand washing by healthcare professionals?

A
  • no bacterial resistance
  • quicker to use
  • less drying than soap
  • works well in presence of blood
28
Q

cresol

A

a phenolic from the greasewood bush used to prevent the rotting of wooden posts, fences, railroad ties, etc.

29
Q

hexachlorophene

A

a chlorinated phenol; used in soaps & lotions (Physohex); now known to increase risk of brain damage in babies

30
Q

iodophor

A

a halogen; a mixture of iodine & surfactants; used for surgical scrubs and to disinfect skin before surgery

31
Q

ethanol

A

an alcohol; widely used as skin antiseptic; a 50-70% solution in water is the most effective

32
Q

soaps/detergents

A

surfactants

wash away microbes, but don’t kill them

33
Q

hydrogen peroxide

A

used as an antiseptic & disinfectant

bubbles when it comes in contact with tissue

34
Q

iodine tincture

A

a halogen
a mixture of iodine & alcohol
used as an antiseptic

35
Q

formalin

A

alkylating agent
used to preserve tissues & to embalm
low concentrations are used to inactivate microbes for vaccines

36
Q

chlorine (Chlorox)

A

a halogen
household bleach
added to drinking water & swimming pools

37
Q

lysol

A

a phenolic
common ingredient in household & hospital disinfectants
remains active in the presence of blood & feces

38
Q

ethylene oxide

A

alkylating agent
gas
used to sterilize heat sensitive materials
toxic to humans

39
Q

silver nitrate

A

heavy metal

applied to newborn’s eyes to prevent gonorrhea

40
Q

merthiolate

A

heavy metal containing mercury
antiseptic
basic first aid kit supplies
contains thimerosal

41
Q

quats

A

surfactant
widely used as antiseptic for skin, mucous membranes & wounds; preop prep of skin, surgeon’s hands/arms
don’t kill spores
effectiveness decreased in presence of soap
supports Pseudomonas growth

42
Q

wetting agent

A

a surfactant added to another chemical agent to help them penetrate fatty substances

43
Q

selenium sulfide

A

heavy metal used to treat fungal skin infections

included in dandruff shampoos

44
Q

crystal violet

A 
also known as gentian violet; blocks cell wall synthesis
inhibits G(+) bacteria & yeasts
45
Q

betadine/isodine

A

a halogen
a mixture of iodine & surfactants
used for surgical scubs & to disinfect skin before surgery

46
Q

zephiran/cepacol/bactine

A

surfactant
widely used
effectiveness decreased in presence of soap
supports Pseudomonas growth

47
Q

triclosan

A

phenol used in many antibacterial soaps & cutting boards

48
Q

chlorhexidine

A

biguanide
used in mouthwashes, surgical hand scrubs, skin creams
to teat gum disease (Peridex, Perioguard, Periochip)
interferes with Vit. K absorption
teeth staining occurs when taking iron

49
Q

chloramines

A

now used by water treatment facilities to disinfect drinking water

50
Q

copper sulfate

A

heavy metal used as a fungicide on crops & produce;

used as an algaecide & a molluscicide

51
Q

sodium nitrate

A

prevents germination of Clostridium botulinum spores in meats

52
Q

mercurochrome

A 
heavy metal containing mercury
antiseptic
"monkey blood"
now banned by FDA
now contain quits instead
53
Q

thimerosal

A

heavy metal containing mercury
found in merthiolate
also used as a vaccine preservative & in cosmetics, nasal sprays, etc.

54
Q

povidone-iodine (PVP iodine)

A

a halogen
mixture of iodine & surfactants
used for surgical scrubs and to disinfect skin before surgery

55
Q

PCMX (nanotechnology)

A

charged nano spheres of oil droplets

disrupt cell envelope

56
Q

What are advantages of using PCMX (nanotechnology)

A

non-corrosive
non-irritating
kills quickly
doesn’t require EPA handling, warning or precaution
works well as Quats & chlorine-based products

Microbiology Unit 2 (6 decks)

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