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BIO 204 Microbiology > Ch 11-12 > Flashcards

Ch 11-12 Flashcards

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1
Q

What is disinfection?

A

Destroys most microbial life, reducing contamination on inanimate surfaces

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2
Q

What is sterilization?

A

The destruction of all microbial life

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3
Q

What is sanitation (decontamination)?

A

The mechanical removal of most microbes from an animate or inanimate surface

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4
Q

What is antisepsis (degermation)

A

The same as disinfection, but on living surface

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5
Q

Compare different microbial forms and resistance to physical and chemical controls

A

*figure 11.1

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6
Q

What is tyndallization?

A

Early process of sterilization of food

-heating it repeatedly below boiling; each heating the bacteria developed from the resistant spores are destroyed

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7
Q

What are the minimum sterilizing conditions in a steam autoclave?

A

121*C at 15 psi for 15 minutes

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8
Q

How are beverages like apple juice or milk disinfected?

A

Pasteurization

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9
Q

What is pasteurization?

A
  • Reduces the number of vegetative form

- Used to eliminate pathogenic microbes and lower microbial numbers

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10
Q

What is the difference between the types of pasteurization?

A
  • Batch method
  • Flash pasteurization
  • Ultrahigh-temperature pasteurization
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11
Q

What is thermal death time?

A

The shortest length of time required to kill all test microbes at a specified temperature

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12
Q

What is thermal death point?

A

The lowest temperature required to kill all microbes in a sample in 10 minutes

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13
Q

Why is UV light not an effective control for killing microbes in a capped tube?

A

UV light only kills on the surface; it does not penetrate. It can also be harmful to humans.

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14
Q

What are the targets of antimicrobial agents?

A
  • cell wall
  • cell membrane
  • cellular synthetic processes (DNA/RNA)
  • proteins
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15
Q

Which targets of antimicrobial agents may also impact our cells?

A
  • cell membrane
  • cellular synthetic processes (DNA/RNA)
  • proteins
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16
Q

What is bacteriocidal?

A

A chemical that destroys bacteria except for those in the endospore stage

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17
Q

What is bacteriostatic?

A

Prevent the growth of bacteria on tissues or objects in the environment

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18
Q

What is the difference between bacteriocidal and bacteriostatic?

A

Bacteriocidal agents destroy bacteria except for those in endospore stages while bacteriostatic agents prevent the growth of bacteria on tissues or objects in the environment

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19
Q

How do cold vs hot temps affect microbes in general?

A

Hot temperatures allow for shorter exposure time while lower temperatures require longer exposure times.

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20
Q

What is lyophilization?

A
  • a combination of freezing and drying
  • common method of preserving microbes and other cells in a viable state
  • pure cultures are frozen instantaneously and exposed to a vacuum that removes water
21
Q

What is desiccation?

A

Dehydration of vegetative cells directly exposed to normal room air

22
Q

How can one know if microbial death has occurred?

A

No microbes reproduce.

23
Q

What are antibiotics?

A

Any of a large group of chemical substances, as penicillin or streptomycin, produced by various microorganisms and fungi, having the capacity in dilute solutions to inhibit the growth of or to destroy bacteria and other microorganisms, used chiefly in the treatment of infectious diseases

24
Q

What is the difference between broad-spectrum and narrow-spectrum antimicrobials?

A

Broad-spectrum drugs are effective against more than one group of bacteria (tetracyclines) while narrow-spectrum drugs only target a specific group (Polyhymnia/penicillins)

25
Q

What are important characteristics for antimicrobial drugs?

A

-low toxicity for human tissues
-high toxicity against microbial cells
-do not cause serious side effects
-stable and soluble in body tissues and fluids
TABLE 2.1

26
Q

What factors affect germicidal activity?

A

The material being treated

  • length of exposure
  • strength of germicide
27
Q

How do surfactants work?

A

Dissolves lipids, disrupts membranes, denatures proteins, and inactivated enzymes in high concentration; act as wetting agent in low concentrations
- works to disrupt the plasma membrane–creates channels though it.

28
Q

In what ways do antimicrobials target the cell wall?

A

Damage to the cell wall:

  • blocks cell wall synthesis
  • digesting the cell wall
  • breaking down the surface of the cell wall
29
Q

Antibiotics that disrupt prokaryotic ribosomes would affect what in humans?

A

Eukaryotic Mitochondrian

30
Q

Historically, what was used to help prevent gonococcal infections in newborns?

A

Silver nitrate

31
Q

How are broad-spectrum drugs involved in superinfections?

A
  • treats infections
  • destroys normal biota, even those far removed from the original infection
  • example is a UTI
32
Q

Why are there fewer antifungal, anti protozoan, and antihelminth drugs compared to antibacterial drugs?

A

These organisms are so similar to human cells that drug selective toxicity is difficult

33
Q

What are the targets of antimicrobials?

A

1) Cell wall synthesis
2) Cell membrane function
3) Nucleic acid synthesis
4) Protein synthesis
5) Action as antimetabolites

34
Q

What are mechanisms of bacterial resistance to antimicrobics?

A
  • New enzymes are synthesized
  • permeability or uptake of the drug into a bacterium is decreased
  • drug is immediately eliminated
  • binding sites for drug are decreased in number or affinity
  • an affected metabolic pathway is shut down or alternative pathway is used
35
Q

How does each mechanism of bacterial resistance to antimicrobics work?

A

.

36
Q

What is drug susceptibility testing?

A

Determines the pathogens response to various antimicrobiotics

37
Q

What is chemotherapy?

A

The treatment of disease by means of chemicals that have a specific toxic effect upon the disease-producing microorganisms or that selectively destroy cancerous tissue

38
Q

What are prebiotics?

A

Nutrients that encourage the growth of beneficial microbes in the intestine

39
Q

What are probiotics?

A
  • preparations of live microorganisms fed to animals and humans to improve intestinal biota
  • replace microbes lost during antimicrobial therapy
  • augment the biota already there
40
Q

What is MIC (minimum inhibitory concentration)?

A

the smallest concentration (highest dilution) of drug that visibly inhibits growth

  • useful in determining the smallest effective dosage of a drug
  • provides a comparative index against other antimicrobials
41
Q

How does MIC work?

A

minimum inhibitory concentration (MIC) is the lowest concentration of an antimicrobial drug that will inhibit the visible growth of a microorganism after overnight incubation.

42
Q

What is selective toxicity?

A
  • central concept in antibiotic treatment
  • antimicrobial drug should kill or inhibit microbial cells without simultaneously damaging host tissues
  • the best drugs in current use block the actions or synthesis of molecules in microorganisms but not vertebrate cells
43
Q

What is the therapeutic index?

A

the ratio of the dose of the drug that is toxic to humans to its minimum effective (therapeutic) dose

44
Q

What are modes of action for antivirals?

A
  • barring penetration of the virus into the host cell
  • blocking the transcription and translation of viral molecules
  • preventing maturation of viral particles
45
Q

How does microbial resistance occur with mutations?

A

Resistance through spontaneous mutation

  • minimal chance that the mutation will be adventurous
  • smaller chance that they mutation ill confer drug resistance
  • large microbial populations and constant rate of mutation ensures that such mutations occur
46
Q

What are contributing factors to emerging drug resistance?

A

Resistance through horizontal transfer:
-Resistance Factors:plasmids that are transferred through conjugations, transformation, or transduction

Transposable drug resistance sequences(transposons):
Duplicated and inserted from one plasmids to another or from the plasmid of the chromosome

Sharing of resistance genes accounts for the rapid proliferation of drug-resistant species:

  • genes transfers are extremely frequent in nature
  • genes from unrelated bacteria, viruses, and other organisms live in the body’s normal biota and environment
47
Q

What are mechanisms for drug resistance transfer between microbes?

A

Enhanced surveillance mechanisms

  • Pulse Net,WHONET
  • Track food-borne pathogens and pathogenic microbial populations
  • provides up-to-date views of the changes in resistance genes
48
Q

How is the Kirby-Bauer plate used?

A

Kirby-Bauer testing measures sensitivity of bacteria to antibiotics by culturing bacteria on solid growth media surrounding sources of drug.

  • the surface of a plate of special medium is spread with test bacterium
  • small discs containing pre measured amounts of antibiotics are dispensed onto the bacterial lawn
  • a sone of inhibition formed during incubation is measured and compared with a standard for each drug

BIO 204 Microbiology (12 decks)

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