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Microbiology > Control microorganisms > Flashcards

Control microorganisms Flashcards

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1
Q

Name all control microorganisms

A
  • Sterilization: killing all organisms
  • Decontamination: Making safe for use
  • Inhibition: limiting the growth of microorganisms
  • ## Disinfection: killing pathogenic microorganisms
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2
Q

What are physical methods to kill microorganisms?

A
  • Heat
  • Radiation
  • Filtration
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3
Q

What are chemical methods used on external surfaces?

A

Sterilants,disinfectants,sanitizers, antiseptics.

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4
Q

What are chemical methods used internally?

A

antibiotics, antivirals, antifungals

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5
Q

What is the decimal reduction time?

A

Time to reduce population of one tenfold

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6
Q

If temperature increase, decimal reduction time…

A

decrease!

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7
Q

The time necessary to kill a defined fraction is _________ of the initial cell concentration (90%). But the thermal death time is ________ of the initial cell concentration.

A

indenpendant

dependant

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8
Q

True or false

Different microorganisms have the same decimal reduction time if same temp. is used.

A

False, Different microorganisms have different decimal reduction time.

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9
Q

What is the thermal death time?

A

Time needed to kill all cells at a given temperature

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10
Q

True or false

Endospores need more time than vegetative cells to be killed by heat

A

True

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11
Q

What is autoclave?

A

a sealed device that uses steam under pressure, killing endospores in a decent amount of time (10-15 min). Water goes above 100 degres

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12
Q

What are the 2 different type of pasteurization?

A

Flash pasteurization: 72°C for 15s.

Bulk pasteurization: 65°C, 30min.–> cheaper, diff. taste

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13
Q

What is pasteurization?

A

is the process of using precisely controlled heat to reduce the microbial load in heat-sensitive liquids.

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14
Q

True or False:

Pasteurization kills all microorganisms.

A

False. It kills a lot of pathogenic microorganisms, but doesn’t kill everything.
Reduces the microbial load, increases the shelf life of the product.

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15
Q

What is the effect of radiation on microorganisms?

A

It reduces microbial growth.

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16
Q

What is the effect of UV light on microorganisms?

A

UV has sufficient energy to cause modifications and breaks in DNA, which inhibit replication, transcription and cause death.

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17
Q

What is ionizing radiation?

A
  • Electromagnetic radiation that produces ions and other reactive molecules.
  • Generates ions and hydroxyl radicals
  • Sources of radiation include cathode ray tubes (electrons), X-rays, and radioactive nuclides
  • Radiation is used for sterilization in the medical field and food industry
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18
Q

What is one positive aspect of filter sterilization?

A

Filtration avoids the use of heat on sensitive liquids and gases

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19
Q

Name 2 types of filters.

A

Depth filters and membrane filters

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20
Q

What is the difference between depth and membrane filters?

A

DEPTH FILTERS: Fibrous sheet or mat made from an
array of fiber (paper or glass). Used to sterilize liquid, air. HEPA filters

MEMBRANE FILTERS: Function more like a sieve
A type of membrane filter is the nucleation track (nucleopore) filter.
Filtration speed can be increase by syringe, pump, or vacuum

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21
Q

Antimicrobial agents can be classified as: (3 things..)

A
  • Bacteriostatic
  • Bacteriocidal
  • Bacteriolytic
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22
Q

What is the definition of Bacteriostatic?

A

Inhibits growth of microorganisms

23
Q

What is the definition of Bacteriocidal?

A

Kill all cells

24
Q

What is the definition of Bacteriolytic?

A

Kill cells by inducing lysis

25
Q

Name 4 ways to measure antimicrobial activity

A
  • Minimum inhibitory concentration
  • Minimum lethal concentration
  • Minimum bacteriocidal concentration
  • DEcimal reduction time
  • Disc diffusion assay
26
Q

What is the definition of minimum inhibitory concentration?

A

smallest amount of an agent to inhibit growth of microorganism.

27
Q

What is the definition of minimum lethal concentration

A

smallest amount of an agent that kills test ORGANSIMS

28
Q

What is the definition of minimum bacteriocidal concentration?

A

smallest amount of an agent that kills test BACTERIA

29
Q

What is a disc diffusion assay?

A
  • Antimicrobial agent is added on a paper disc…
  • MIC is reached at some distance of the disc
  • Zone of inhibition= area where there is no growth
30
Q

What are antimicrobial agents used for?

A

Used to prevent spreading of a pathogen in a certain envrionment. Prevent contamination of a host, cure superficial bacterial infection.

31
Q

Describe the 2 categories of antimicrobial agents for external use.

A
  1. Antimicrobial agents used in commercial and industrial application (ex: chemicals in paper, air conditionning…
  2. Products used to prevent growth of human pathogens in inanimate environments and on external body surfaces. –> sterilants, sanitizers, desinfectants and antiseptics
32
Q

What antimicrobial agent kills all microorganisms incluing endospores?

A

Sterilants. Also called cold sterilization

33
Q

What do disinfectants and sanitizers do?

A

applied to nonliving objects or surface (can be toxic for animals/humans). Do not kill endospores.

34
Q

What do antiseptics do?

A

applied to the surface of living :ssues or skin (must not be toxic for animals/humans). Do not kill endospores.

35
Q

What are antimicrobial drugs?

A

Antibiotics, antifungals, antivirals: applied outside or inside the body of animals/humans (must not be toxic for animals/humans). Do not kill endospores.

36
Q

What is an exemple of an agent that is a disinfectant, antiseptic and sterilant?

A

Halogens (but they are not all at the same time….)

Sodium Hypochlorite

37
Q

What is a positive aspect of antimicrobial drugs?

A

Can be used on humans and animals because they have minimal side effect on the host—> because they have a specific target —> target a specific thing in the bacteria

38
Q

What are the characteristics of a good antimicrobial drug?

A
  • NO severe side effects, must be far more toxic for bacteria than mammalian cells.
    – Low risk/benefit ra:o.
    – Broad spectrum of ac:vity to facilitate rapid medical intervention.
    – Appropriate bioavailability and pharmacokinetics (must reach the site of infection).
    – Low cost to develop and manufacture.
39
Q

What is selective toxicity?

A

is is the ability to kill a phatogen without affecting the host

40
Q

Who specifically studied selective toxicity in the early 1900s?

A

Paul Ehrlich

41
Q

Name 4 synthetic antimicrobial drugs.

A
  • Ionazid
  • Nucleic acid base analogs
  • Quinolones
  • Sulfa drugs
42
Q

What is ionazid and give and exemple.

A

Ionazid is a synthetic antimicrobial drug. interfers with synthesis of mycolic acid. Works only against MYCOBACTERIUM.

43
Q

What is a growth factor analog and give exemples.

A

Growth factor analog are structurally similar to growth factors but do not function in the similar way the cell. Sulfa drugs and Ionazids are growth factor analogs.

44
Q

What are sulfa drugs. Give an exemple.

A

Sulfa drugs are growth factor analogs. They are bacteriostatic. SULFANILAMIDE is an exemple.

45
Q

What are nucleic acid base analogs, what do they do, give an exemple.

A

They are formed by bromine and fluorine. They stop DNA replication and translation.

46
Q

What are Quinolones?

A

Antibacterial compounds that interfere with DNA GYRASES (control DNA supercoiling).

47
Q

What are antibiotics?

A

ANTIMICROBIAL AGENT that are NATURALLY PRODUCED by a variety of bacteria or fungi to kill or inhibit other microorganisms.

48
Q

true or false

Antibiotics can be modified in a laboratory.

A

true. They are called semisynthetic antibiotics.

49
Q

Why do Gram + and Gram - bacteria rect differently to antibiotics?

A

Because of cell wall.. major factor…

50
Q

What is the most important antibiotic group of all times?what antibiotics does it include?

A

b-lactams. Includes PENICILLINS, CEPHALOSPORINS, and CEPHAMYCINS.

51
Q

Describe penicillins.

A
  • Discovered by FLEMING
  • Primarily efficient agains GRAM +
  • Some synthetic forms are also effective agains gram-
  • INHIBITS CELL WALL SYNTHESIS
52
Q

Describe cephalosporins.

A
  • b-lactam antibiotic
  • produced by a fungus (Cephalosporium)
  • Same mode of action as the penicillin
  • Commonly used to treat ghonorrea
53
Q

Describe the mode of action of B-Lactams

A

penicillin binds to transpeptidase. B-lactams are BACTERIOCIDAL or BACTERIOLYTIC (depending..) . Can also be bacteriostatic.

54
Q

Name Antibiotics made by prokaryotes.

A

Aminoglycosides
Chloramphenicol
Macrolides
tetracyclines

Microbiology (11 decks)

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