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BIOL 222 > Ch. 7 The Control of Microbial Growth > Flashcards

Ch. 7 The Control of Microbial Growth Flashcards

1
Q

Ignaz Semmelweis (1816 - 1865)

A

He started washing his hands between births, because people would sometimes go straight from an autopsy to a birth. He also used disinfectants. Bed fever went from 18% to 1% occurrence. People resisted these practices and he died at 47.

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2
Q

Joseph Lister (1827 - 1912)

A

He sterilized surgical instruments by boiling them. It decreased infection rates and it started aseptic surgery practices.

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3
Q

Sterilization

A

Destruction or removal of all forms of microbial life, including endospores but with the possible exception of prions.

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4
Q

Commercial sterilization

A

Sufficient heat treatment to kill endospores of clostridium botulinum

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5
Q

Disinfection

A

Destruction of vegetative pathogens on inanimate objects

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6
Q

Antisepsis

A

Destruction of vegetative pathogens on living tissues

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7
Q

Degerming

A

Removal of microbes from a limited area, such as the skin around an injection site

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8
Q

Sanitization

A

Treatment is intended to lower microbial counts on eating and drinking utensils to safe public health levels

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9
Q

Biocide/germicide

A

Kills microbes

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10
Q

Bacteriostasis

A

No more growth (static)

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11
Q

Sepsis

A

Contamination with microbes

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12
Q

Asepsis

A

Without microbial contamination

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13
Q

Rate of microbial death is always …

A

The rate of death is always a constant. For example, if 90% of bacterial are killed in the first minute, then another 90% of the new population will be killed in the second minute, and so on.

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14
Q

The number of microbes influence the

A

Time spent disinfecting

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15
Q

When graphed on a logarithmic scale, and low population of microbes will have a _______ time to disinfect and a larger population of microbes will have a _____ time to disinfect

A

Shorter.

Longer.

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16
Q

Environmental conditions affecting microbial growth/control of growth

A

ur mom

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17
Q

Temperature

A

Heat can denature proteins and enzymes necessary for microbial growth

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18
Q

Presence of organic matter (blood, feces, vomit, etc)

A

May make it more difficult to sterilize, and one may have to add extra disinfectant

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19
Q

pH

A

A lot of bacterial are neutrophiles. Acidity can be helpful in preventing growth.

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20
Q

Time of exposure

A

More time = more microbes killed. The individual characteristics of microbes also affects how their growth can be controlled.

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21
Q

Actions of anti-microbial agents

A

Damage proteins and nucleic acids or affect membrane permeability

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22
Q

Physical methods of disinfection - Heat

A

Denatures proteins. Very effective. Cannot be used on the human body or on vaccines

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23
Q

Measures of heat resistance - thermal death point (TDP)

A

Incubate tubes (liquid culture) of microbes for 10 minutes at different temperatures. The lowest temp with all dead = TDP.

24
Q

Thermal death time (TDT)

A

A given (constant) temperature for different times for each tube. The shortest amount of time where all the microbes have died = TDT.

25
Q

Decimal reduction time (DRT)

A

Amount of time that 90% are killed. Used in canning. It is different for every microbe, so there are tables for this.

26
Q

Moist heat

A

More effective than dry heat. It breaks hydrogen bonds faster.

27
Q

Boiling

A

At 100 C for 10 minutes (at sea level) destroys most vegetative cells.

28
Q

Autoclave

A

Steam under pressure. It hotter that way, and it takes less time to sterilize. 15 psi for 15 minutes is the starting setting. Sometimes more like 30 minutes. More volume = more time needed.

29
Q

Pasteurization

A

Can kill most pathogens. Not all microbes. Used for foods like yogurt. High temp for a short time, 72 C for 15 seconds. (HTST).

30
Q

Ultra high temp treatment (pasteurization)

A

140 C for 4 seconds.

31
Q

Dry heat

A
  • Direct flaming (transfer hook)
  • Incineration: to ash. for infectious materials you wont used again.
  • Hot air sterilization: 170 C for 2 hrs (Know this!)
32
Q

Equivalent treatments

A

15 psi for 15 minutes = 170 C for 2 hrs

33
Q

Filtration

A

Used for heat sensitive materials, and only for liquids or gases. Contains a membrane filter that usually has a pore size of 0.22 nm. 0.45 nm for some viscous liquids, but some viruses pass this size.

34
Q

HEPA filter

A

Air is drawn down and through a chamber so that the air is free of microbes. Used in the OR and in burn units.

35
Q

Low temp

A

Bacteriostatic = reduces growth. Refrigerator (4 C or lower). Freezing is 0 C or lower. Crystal formation in cell walls from freezing temps can kill them.

36
Q

High pressure

A

Kills bacteria. Preserves flavor, color, nutrients or foods.

37
Q

Desiccation

A

Bacteriostatic. Drying foods. No water? no microbes. Drying + pressure = hell yea. Variable resistance by different organisms. Extends food life.

38
Q

Osmotic pressure

A

High concentration of solutes can lead to plasmolysis. Bacteriostatic as well. Molds and yeasts are more resistant to this. Think about molds growth on jam.

39
Q

Radiation

A

Can preserve food. Preserves vaccines.

40
Q

Ionizing radiation

A

To sterilize plastic tools. Doesn’t let protein stick to it. Penetrates plastic.

41
Q

Gamma, x-rays, high energy radicals are

A

Simply high energy wavelengths that can kill cells by the formation of hydroxyl radicals.

42
Q

UV light

A

non-ionizing radiation. Forms covalent bonds between bases that shouldn’t have those bonds. This causes abnormal base-pairing and mutations. Thymine dimers in DNA. Kills DNA.

43
Q

Visable blue light and microwaves?

A

blue light (470 nm) kills MRSA in mice and cultures. microwaves dont kill directly. Maybe the heat generated can a little bit.

44
Q

Chemical methods.

A

There are a couple tests that can be used to evaluate a disinfectant

45
Q

Use-dilution test

A

A process of dipping cultures into disinfectants and then putting the “disinfected” cultures into fresh media to see how much bacterial growth is produced.

46
Q

Disk diffusion method - Kirby bower test

A

Cover petri dish with a culture and put disinfectant or anti-microbial drug on the surface and see whats effective by seeing how far the zone of inhibition spreads.

47
Q

Types of disinfectants

A

Responsible for knowing only the ones mentioned in class

48
Q

Essential oils (EO)

A

Not actually necessary essential. Extracts for plants that can be used on hard surfaces or skin. Non-toxic. Pleasant odor. Biodegradable.

49
Q

Halogens for disinfecting

A

Chlorine and iodine

50
Q

Tincture

A

Solution with alcohol. Iodophor is iodine with organic molecule (betadine exp).

51
Q

Chlorine

A

A gas. Forms HoCl acid in water which oxidizes certain molecules. NaOCL (Clorox) is an acid to disinfect hard surfaces with.

52
Q

Alcohols

A

Dehydrate proteins and dissolve lipids.

53
Q

Ethanol and isopropanol

A

Both effective at 60 - 95% because water is needed for reactions that destroy pathogens. Used in tinctures and hand sanitizers (require time to work).

54
Q

Surface-active agents

A

Soaps and detergents. Not antiseptic. De-germing. A surfactant that breaks oil layers and removes microbes from hands/surfaces.

55
Q

Heavy metals

A

Antimicrobial components. Silver, mercury, copper, zink. Denatures proteins in an oligodynamic action.

56
Q

Silver nitrate eyedrops for new borns?

A

Not used anymore. Was used to prevent the newborn from contracting the mother’s gonorrea. Now other antibiotics are used, and they also detroy clostridium. The disorder was called opthalmia neonatorum.

57
Q

Microbial characteristics and resistance.

A

Most resistant to least resistant –>

  • Prions
  • Bacterial spores
  • Small, non-enveloped viruses
  • Mycobacteria
  • Fungal spores
  • Gram-neg bacilli
  • vegetative fungi and algae
  • Large non enveloped viruses
  • Gram-pos bacteria
  • Enveloped viruses

BIOL 222 (22 decks)

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