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Microbio Midterm II > Lecture 9: Control of Microorganisms > Flashcards

Lecture 9: Control of Microorganisms Flashcards

1
Q

What is sterilization?

A

Killing all viable organisms (including spores)

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2
Q

What is inhibition?

A

Effectively limiting microbial growth.

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3
Q

What is decontamination?

A

Washing object so it’s safe to handle

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4
Q

What is disinfection?

A

Directly targets removal of all pathogens, not necessarily all microorganisms.

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5
Q

What are the physical methods of antimicrobial control?

A

Heat, Pasteurization, Radiation, Filters.

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6
Q

What is decimal reduction time?

A

Amount of time required to reduce viability tenfold. Inversely correlated with temperature. (100%->10%)

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7
Q

What is thermal death time?

A

Time needed to kill all cells at a given temperature. Dependent on cell #.

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8
Q

How long can endospores resist boiling?

A

5 min for 1 decimal reduction.

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9
Q

How does an autoclave sterilize things?

A

Uses steam under pressure that reaches 121C, sterile in 10-15 min.

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10
Q

What is pasteurization?

A

Using precisely controlled heat to reduce microbial load in heat sensitive liquids.

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11
Q

What is flash pasteurization?

A

72C for 15s

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12
Q

What is bulk pasteurization?

A

65C for 30 min (Harsher on milk)

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13
Q

What kind of radiation is used for antimicrobial control?

A

Microwaves, UV, X rays, gamma, electons

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14
Q

How does UV decontaminate surfaces?

A

Has enough energy to modify DNA

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15
Q

Why can C.botulinum and O. radiodurans withstand radiation?

A

Botulinum forms spores, Radiodurans is very effective at repairing DNA.

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16
Q

What is ionizing radiation?

A

electromagnetic radiation, produces ions/reactive molcs. Damage DNA and proteins.

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17
Q

What is filter sterilization?

A

Pores of filters too small for organisms to pass=left on filter.

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18
Q

Whats the difference between depth and membrane filters?

A

Depth=Fibrous sheet, lots of strands.

Membrane=nucleopores

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19
Q

What are the different kinds of chemical methods to combat microbial growth?

A

Antimicrobial agents, Antimicrobial drugs, Antivirals, antifungals

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20
Q

What does bacteriostatic mean?

A

Inhibit growth of microorganisms.

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21
Q

What does bacteriocidal mean?

A

Kill Microorganisms

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22
Q

What does bacteriolytic mean?

A

Kill microorganism by inducing lysis. (triangle graph)

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23
Q

What is the minimum inhibitory concentration? (MIC)

A

Smallest amount of an agent needed to inhibit growth of microorganism

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24
Q

What is the minimum lethal concentration? (MLC)

A

Lowest concentration of agent that kills a test organism

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25
Q

What is the minimum bacteriocidal concentration? (MBC)

A

Lowest concentration of agent that kills test bacteria

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26
Q

What is a disk diffusion assay?

A

Antimicrobial disk added to agar=MIC reached at some distance (further away=less antibiotic)

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27
Q

What is a sterilant?

A

Destroys all forms of microorganisms, including endospores. (Cold sterilization)

28
Q

What are disinfectiants/sanitizers? (ie lysol)

A

Don’t kill endospores. Can be toxic to humans.

29
Q

What are antiseptics?

A

Don’t kill endospores. Non toxic

30
Q

What are antimicrobial drugs?

A

Ie antibiotics, antifungals, antivirals. Non toxic, don’t kill endospores.

31
Q

What are Phenols?

a. Disinfectant
b. Sterilant
c. Antiseptic

A

A and C

32
Q

What are Alcohols?

a. Disinfectant
b. Sterilant
c. Antiseptic

A

A and C

33
Q

What are Halogens?

a. Disinfectant
b. Sterilant
c. Antiseptic

A

All of the above.

34
Q

What are heavy metals?

a. Disinfectant
b. Sterilant
c. Antiseptic

A

A

35
Q

What is ammonium?

a. Disinfectant
b. Sterilant
c. Antiseptic

A

A and C

36
Q

What are alkylating agents?

a. Disinfectant
b. Sterilant
c. Antiseptic

A

A and B

37
Q

Why do many antimicrobial drugs target 30s rRNA?

A

It is the ribosome subunit present in prokaryotes but not eukaryotes.

38
Q

What are growth factor analogs? (ie sulfanilamide)

A

Structurally similar to GFs, but don’t function.

39
Q

What does sulfanilamide (Sulfa drug) inhibit?

A

Is an analog of P-aminobenzoic acid, bacteriostatic. Inhibits folic acid synth.

40
Q

What is isoniazid an analog of?

A

Growth factor, stops synth of cell wall component.

41
Q

How do nucleic acid base analogs work?

A

Formed by addition of Br or F to base, it stops DNA replication.

42
Q

How to quinolones work?

A

Antibacterial, interfere with DNA gyrase. Controls DNA supercoiling.

43
Q

What are antibiotics?

A

Antimicrobial agents that are naturally produced.

44
Q

What is penicillin primarily effective against?

A

Gram positive bacteria. Synthetic forms can be effective against gram -

45
Q

True or false. The Beta lactam ring has a modifiable R group.

A

True

46
Q

What are cephalosporins produced by?

A

Fungus

47
Q

What two rings are in cephalosporins?

A

B lactam and dihydrothiazine rings. Commonly used for gonorrhea.

48
Q

What does the B lactam ring inhibit?

A

The final transpeptidation step in peptidoglycan synthesis. It is facilitated by a transpeptidase which is a penicillin binding protein. Inactivated when bound.

49
Q

How does the B lactam ring inhibit peptidoglycan synthesis?

A

No transpeptidase=hole in cell wall.

50
Q

Are B lactams bacteriocidal or bacteriolytic?

A

Both. Can actually be bacteriostatic in isotonic solution.

51
Q

True or false. Many antibiotics effective against bacteria are also produced by bacteria.

A

True

52
Q

What are aminoglycosides made by? (Streptomycin)

A

Prokaryotes

53
Q

What is Chloramphenicol made by?

A

Prokaryotes

54
Q

What are macrolides (erythromycin) made by?

A

Prokaryotes

55
Q

What are tetracyclines made by?

A

Prokaryotes

56
Q

What do aminoglycosides target?

A

30s subunit=misreading of mRNA. Bacteriocidal

57
Q

What does Chloramphenicol target?

A

Bind to 23s subunit, block peptide elongation. Bacteriostatic.

58
Q

What do macrolides (erythromycin) target?

A

50s subunit, block protein synth. Bacteriostatic.

59
Q

What do tetracyclines target?

A

30s subunit, block protein synth.

60
Q

How do microbes gain antibiotic resistance?

A

Acquire new gene on R plasmid.

61
Q

What do most successful antivirals do?

A

Block reverse transcriptase and production of viral DNA.

62
Q

What do protease inhibitors do? (Antiviral)

A

Inhibit processing of large viral proteins into components.

63
Q

What do fusion inhibitors do? (Antiviral)

A

Prevent viruses from successfully fusing with host cell

64
Q

What particular problem do antifungals have?

A

Fungus are eukaryotes=use a lot of the same functions as humans.

65
Q

What do antifungals target?

A

ergosterol synthesis (Fluconazole) , cell wall synthesis.

66
Q

What are the mechanisms microbes use to become resistant to antibiotics?

A
  • Destruction/modification of antibiotic structure
  • modification of target site
  • Modification of antibiotic uptake mechanism
67
Q

What are the mechanisms microbes use to become tolerant to antibiotics?

A
  • lack target sites (ie no peptidylglycan)
  • modify target sites
  • lack uptake mechanism

Microbio Midterm II (7 decks)

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