Controlling microorganisms and antimicrobial drugs

Question 1

what is pasteurization?

Answer 1

Moist heat method to reduce pathogens without affecting texture, color, or taste

Question 2

what is the low temperature long time pasteurization of milk?

Answer 2

(LTLT) (63C for 30 min)

Question 3

what is the high temperature short time pasteurization of milk?

Answer 3

(72C for 15 sec)

Question 4

what are the conditions for the ultra high temperature treatment? what does it achieve?

Answer 4

134C (2730F) for 1-2 sec, then rapid cooling
Achieves sterilization and unrefrigerated shelf-life up to 6 months.

Question 5

what UV light wavelength is bactericidal?

Answer 5

UV light is bactericidal between 200-300nm (254nm)

Question 6

what does UV light do to the DNA of microbes?

Answer 6

UV light causes Thymidine dimers in DNA

Question 7

what is boiling a method of?

Answer 7

Moist heat method of boiling water (100C) that kills vegetative cells of bacteria and fungi, protozoan trophozoites, most viruses

Question 8

what are the four different moist heat methods?

Answer 8

Boiling
Autoclaving
Pasteurization
Ultrahigh-temperature sterilization

Question 9

what are the three effects of heat on microbes?

Answer 9

1. Denaturation of proteins
2. Interfere with integrity of cytoplasmic membrane and cell wall
3. Disrupt structure and function of nucleic acids

Question 10

how does dry heat affect microbes?

Answer 10

Denatures proteins and oxidizes metabolic and structural chemicals

Question 11

how does dry heat methods differ from moist heat methods?

Answer 11

Requires higher temperatures for longer time than moist heat

Question 12

what is antisepsis?

Answer 12

Killing or removal of disease-producing organisms from living tissues

Question 13

what is disinfection?

Answer 13

Killing or removal of disease-producing organisms from inanimate surfaces; may not result in sterilization

Question 14

what is alcohol’s mode of action against microorganisms?

Answer 14

dehydration, protein denaturation, dissolve membrane lipids

Question 15

what is alcohol’s CDC level of activity?

Answer 15

intermediate

Question 16

what do soaps have that make them good degerming agents?

Answer 16

they have hydrophilic and hydrophobic ends

Question 17

what are surfactants?

Answer 17

surface active chemicals that reduce surface tension of solvents

Question 18

what are cationic detergents?

Answer 18

positively charged organic surfactants

Question 19

what are Quaternary Ammonium Compounds mode of action?

Answer 19

disrupts membrane

Question 20

what is the CDC level of quaternary ammonium compounds?

Answer 20

low

Question 21

what do soaps contain that make them antibacterial?

Answer 21

benzalkonium chloride

Question 22

what three drugs are metabolic inhibitors?

Answer 22

sulfonamides, trimethoprim, metronidazole

Question 23

what five drugs are 50s ribosome inhibitors?

Answer 23

chloramphenicol, macrolides, clindamycin, oxazalidinone and streptogramins

Question 24

what two drugs are 30s ribosome inhibitors?

Answer 24

ahminoglycosides and tetracycline

Question 25

what drug is DNA replication inhibitor?

Answer 25

quinolone

Question 26

what drug is RNA polymerase inhibitor?

Answer 26

rifampin

Question 27

what drug causes cell membrane damage?

Answer 27

polymyxin

Question 28

what five drugs are cell wall inhibitors?

Answer 28

penicillin, cephalosporin, vancomycin, bacitracin, monobactam

Question 29

what type of antibiotic is penicillin?

Answer 29

penicillin is a beta-lactam antibiotic

Question 30

how do beta lactam antibiotics work?

Answer 30

the beta lactam ring is similar to D alanine D alanine part of peptidoglycan.

The beta lactam ring then takes its place while the cell wall is being constructed and makes it weak.

Eventually the cell will lyse.

Question 31

how does tetracycline work?

Answer 31

Binds 30S subunit and blocks tRNA carrying amino acid from entering the A site

Question 32

what is amphotericin B? what does it do?

Answer 32

It is under the polyene category of antifungal drugs.

it disrupts membrane integrity.

Question 33

what are the five mechanisms of antibiotic resistance?

Answer 33

modify the target, destroy the antibiotic, alter the antibiotic, pump the antibiotic out, bypass the metabolic pathway