Lecture 9: Control of Microorganisms

Question 1

What is sterilization?

Answer 1

Killing all viable organisms (including spores)

Question 2

What is inhibition?

Answer 2

Effectively limiting microbial growth.

Question 3

What is decontamination?

Answer 3

Washing object so it’s safe to handle

Question 4

What is disinfection?

Answer 4

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

Question 5

What are the physical methods of antimicrobial control?

Answer 5

Heat, Pasteurization, Radiation, Filters.

Question 6

What is decimal reduction time?

Answer 6

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

Question 7

What is thermal death time?

Answer 7

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

Question 8

How long can endospores resist boiling?

Answer 8

5 min for 1 decimal reduction.

Question 9

How does an autoclave sterilize things?

Answer 9

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

Question 10

What is pasteurization?

Answer 10

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

Question 11

What is flash pasteurization?

Answer 11

72C for 15s

Question 12

What is bulk pasteurization?

Answer 12

65C for 30 min (Harsher on milk)

Question 13

What kind of radiation is used for antimicrobial control?

Answer 13

Microwaves, UV, X rays, gamma, electons

Question 14

How does UV decontaminate surfaces?

Answer 14

Has enough energy to modify DNA

Question 15

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

Answer 15

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

Question 16

What is ionizing radiation?

Answer 16

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

Question 17

What is filter sterilization?

Answer 17

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

Question 18

Whats the difference between depth and membrane filters?

Answer 18

Depth=Fibrous sheet, lots of strands.

Membrane=nucleopores

Question 19

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

Answer 19

Antimicrobial agents, Antimicrobial drugs, Antivirals, antifungals

Question 20

What does bacteriostatic mean?

Answer 20

Inhibit growth of microorganisms.

Question 21

What does bacteriocidal mean?

Answer 21

Kill Microorganisms

Question 22

What does bacteriolytic mean?

Answer 22

Kill microorganism by inducing lysis. (triangle graph)

Question 23

What is the minimum inhibitory concentration? (MIC)

Answer 23

Smallest amount of an agent needed to inhibit growth of microorganism

Question 24

What is the minimum lethal concentration? (MLC)

Answer 24

Lowest concentration of agent that kills a test organism

Question 25

What is the minimum bacteriocidal concentration? (MBC)

Answer 25

Lowest concentration of agent that kills test bacteria

Question 26

What is a disk diffusion assay?

Answer 26

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

Question 27

What is a sterilant?

Answer 27

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

Question 28

What are disinfectiants/sanitizers? (ie lysol)

Answer 28

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

Question 29

What are antiseptics?

Answer 29

Don't kill endospores. Non toxic

Question 30

What are antimicrobial drugs?

Answer 30

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

Question 31

What are Phenols? a. Disinfectant b. Sterilant c. Antiseptic

Answer 31

A and C

Question 32

What are Alcohols? a. Disinfectant b. Sterilant c. Antiseptic

Answer 32

A and C

Question 33

What are Halogens? a. Disinfectant b. Sterilant c. Antiseptic

Answer 33

All of the above.

Question 34

What are heavy metals? a. Disinfectant b. Sterilant c. Antiseptic

Answer 34

A

Question 35

What is ammonium? a. Disinfectant b. Sterilant c. Antiseptic

Answer 35

A and C

Question 36

What are alkylating agents? a. Disinfectant b. Sterilant c. Antiseptic

Answer 36

A and B

Question 37

Why do many antimicrobial drugs target 30s rRNA?

Answer 37

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

Question 38

What are growth factor analogs? (ie sulfanilamide)

Answer 38

Structurally similar to GFs, but don't function.

Question 39

What does sulfanilamide (Sulfa drug) inhibit?

Answer 39

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

Question 40

What is isoniazid an analog of?

Answer 40

Growth factor, stops synth of cell wall component.

Question 41

How do nucleic acid base analogs work?

Answer 41

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

Question 42

How to quinolones work?

Answer 42

Antibacterial, interfere with DNA gyrase. Controls DNA supercoiling.

Question 43

What are antibiotics?

Answer 43

Antimicrobial agents that are naturally produced.

Question 44

What is penicillin primarily effective against?

Answer 44

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

Question 45

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

Answer 45

True

Question 46

What are cephalosporins produced by?

Answer 46

Fungus

Question 47

What two rings are in cephalosporins?

Answer 47

B lactam and dihydrothiazine rings. Commonly used for gonorrhea.

Question 48

What does the B lactam ring inhibit?

Answer 48

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

Question 49

How does the B lactam ring inhibit peptidoglycan synthesis?

Answer 49

No transpeptidase=hole in cell wall.

Question 50

Are B lactams bacteriocidal or bacteriolytic?

Answer 50

Both. Can actually be bacteriostatic in isotonic solution.

Question 51

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

Answer 51

True

Question 52

What are aminoglycosides made by? (Streptomycin)

Answer 52

Prokaryotes

Question 53

What is Chloramphenicol made by?

Answer 53

Prokaryotes

Question 54

What are macrolides (erythromycin) made by?

Answer 54

Prokaryotes

Question 55

What are tetracyclines made by?

Answer 55

Prokaryotes

Question 56

What do aminoglycosides target?

Answer 56

30s subunit=misreading of mRNA. Bacteriocidal

Question 57

What does Chloramphenicol target?

Answer 57

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

Question 58

What do macrolides (erythromycin) target?

Answer 58

50s subunit, block protein synth. Bacteriostatic.

Question 59

What do tetracyclines target?

Answer 59

30s subunit, block protein synth.

Question 60

How do microbes gain antibiotic resistance?

Answer 60

Acquire new gene on R plasmid.

Question 61

What do most successful antivirals do?

Answer 61

Block reverse transcriptase and production of viral DNA.

Question 62

What do protease inhibitors do? (Antiviral)

Answer 62

Inhibit processing of large viral proteins into components.

Question 63

What do fusion inhibitors do? (Antiviral)

Answer 63

Prevent viruses from successfully fusing with host cell

Question 64

What particular problem do antifungals have?

Answer 64

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

Question 65

What do antifungals target?

Answer 65

ergosterol synthesis (Fluconazole) , cell wall synthesis.

Question 66

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

Answer 66

- Destruction/modification of antibiotic structure - modification of target site - Modification of antibiotic uptake mechanism

Question 67

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

Answer 67

- lack target sites (ie no peptidylglycan) - modify target sites - lack uptake mechanism