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LSCI 230 > Control of Microorganisms > Flashcards

Control of Microorganisms Flashcards

1
Q

sterilization

A

the killing or removal of all viable organisms including endospores

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2
Q

inhibitin

A

effectively limiting microbial growth

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3
Q

decontamination

A

the treatment of an object to make it safe to handle

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4
Q

disinfection

A

directly targets the removal of all **pathogens not necessarily all microorganisms

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5
Q

physical methods (examples)

A

heat
radiation
filtration

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6
Q

chemical methods (antimicrobials) (examples)

A

external surfaces: sterilants, disinfectants, antiseptics

internal: antibiotics, antivirals, antifungals

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7
Q

heat

A
  • high temps *denature macromolecules
  • decimal reduction time
  • time necessary to kill a defined *fraction is independent of the initial cell concentration
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8
Q

decimal reduction time

A

D
amount of time required to reduce viability tenfold
inversely correlated with temp
-organism specific

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9
Q

thermal death time

A

time needed to kill all cells at a given temp
dependent on the population size of the microorganism
To compare a standardized number of starting cells is needed.

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10
Q

Endospores and heat

A

survive heat that would rapidly kill vegetative cells
-need higher temp
(resistant to boiling for a long time - 5 min for a decimal reduction ie 90% dead)

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11
Q

autoclave

A

sealed device that uses steam under pressure

  • the high temp NOT pressure kills microbes
  • the sterilization time is when the object being sterilized reaches 120C (NOT the autoclave itself)
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12
Q

Pasteurization

A

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

  • increases shelf life
  • reduces pathogens
  • flash pasteurization 72C for 15s
  • bulk pasteurization 65C for 30 min
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13
Q

Radiation

A

causes modifications and breaks in DNA, inhibits replication, transcription and cuases death

  • cannot penetrate solid, obaque surfaces
  • used in disinfection of water or air
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14
Q

*Ionizing radiation

A

radiation that produces ions and other reactive molecules

  • has a decimal reduction time
  • sources of radiation: cathode ray tube, X-rays
  • used for sterilization in the medical field and food industry
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15
Q

Filter sterilization

A
  • avoids the use of heat on sensitive liquids or gas

- pores of filter are too small for organisms to pass through, so they are caught.

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16
Q

Depth filters

A

fibrous sheet or mate made from an array of fiber

*HEPA filters

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17
Q

Membrane filters

A
  • like sieve
  • nucleopore filter
  • filtration speed can increase by syringe, pump, or vacuum
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18
Q

antimicrobial agents

A

bacteriostatic: inhibit growth of microorganism
bacteriocidal: kill microorganism
bacteriolytic: kill microorganism by inducing lysis
(Think about the associated graphs)

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19
Q

minimum inhibitory concentration

A

smallest amount of an agen needed to inhibit growth of a microorganism

20
Q

minimum lethal concnetration

A

the lowest concentration of an agent that kills a test *organism

21
Q

minimum bacteriocidal concentration

A

the lowest concentration of an agent that kills a test *bacterium

22
Q

Viable counts

A

** MLC and MBC are viable counts

23
Q

disc diffusion assay

A

antimicrobial agent added to a filter paper disk

24
Q

zone of inhibition

A

area of no growth around the disk

25
Q

sterilants

A

destroy all forms of microorganisms, including endospores

26
Q

disinfectants/sanitizers

A

applied to nonliving objects or surface

do NOT kill endospores

27
Q

antiseptics

A

applied to the surface of living tissues
-nontoxic for humans
do NOT kill endospores

28
Q

antimicrobial drugs

A

applied outside or inside the body of animals/humans
-nontoxic for humans
do NOT kill endospores

29
Q

antimicrobial drugs - basic facts

A
  • either **bacteriostatic or **bactericidal

- usually have a *specific target

30
Q

synthetic antimicrobial drugs

A
  • Paul Ehrlich studied **selective toxicity: the ability to inhibit or kill a pathogen without affecting the host
  • *salvarsan: one of the first antimicrobial drugs (syphilis)
31
Q

growth factor analogs

A

structurally similar to growth factors, but do not function in the cell

32
Q

sulfa drugs

A
  • *sulfanilamide is an analogue of p-aminobenzoic acid. Inhibits folic acid synthesis.
  • bacteriostatic
33
Q

isoniazid

A

growth factor analog

interferes with synthesis of mycolic acid

34
Q

nucleic acid base analogs

A

formed by the addition of Br or F, stop DNA replication

35
Q

quinolones

A

interfere with DNA gyrase

antibacterial compounds

36
Q

antibiotics

A

-antimicrobial agents naturally produced by a variety of bacteria and fungi to inhibit or kill other microbes
-semisythetic antibiotics (modified antibiotics to enhance efficacy)
-B-Lactams
cell wall is a major factor in the susceptibility of microbes to antibiotics

37
Q

*******Cephalosporins

A
  • used to treat gonorrhea
  • produced by the fungus Cephalosporium
  • **can be bacteriolytic or bactericidal
  • bacteriostatic in isotonic soutions
38
Q

Penicillins

A

inhibit cell wall synthesis

39
Q

Aminoglycosides

A

Ex. streptomycin

bactericidal

40
Q

Antibiotic producers

A 
tolerant to the antibiotic:
-lack target sites
-no uptake mechanism
resistant:
destriction or **modification of the antibiotic
-modification of the target site etc
41
Q

acquisition of resistance

A
  • the use of antibiotics selects for the spread of R plasmids
  • most drug-resistant genes are located in the R plasmid
42
Q

protease inhibitors

A

inhibit the processing of large viral proteins into individual components

43
Q

fusion inhibitors

A

prevent viruses from successfully fusing with the hose cell

44
Q

Antiviral drugs

A
  • target host structures, resulting in toxicity
  • **risk to the host may not justify the use of antiviral
  • most successful: nucleoside analogs - block reverse transcriptase
45
Q

**Fluconazole

A

anti fungal drug that targets ergosterol synthesis

LSCI 230 (7 decks)

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