DLA1- Controlling Microbial Growth

Question 1

define sterile

Answer 1

free from bacteria or other microorganisms

Question 2

compare sterilization vs commercial sterilization

Answer 2

• regular sterilization is short-term

- commercial sterilization is for long-term shelf lives of foods and other products

Question 3

define disinfection and disinfectant

Answer 3

disinfection is the process of cleaning in order to remove or destroy bacteria with the use of a chemical/disinfectant

Question 4

define antisepsis and antiseptic

Answer 4

antisepsis is the process of cleaning in order to remove or destroy disease causing microorganisms with the use of an antiseptic

Question 5

define sanitization

Answer 5

process of reducing number of microorganisms in order to meet safety standards

Question 6

define degerming

Answer 6

removal of pathogens from living tissues

Question 7

Inert surfaces are treated with which of the following methods: physical, chemical, therapeutic antimicrobials

Answer 7

physical (non-ionizing radiation), chemical (disinfectants)

Question 8

microbiology equipment is treated with which of the following methods: physical, chemical, therapeutic antimicrobials

Answer 8

physical (heat, UV, ethylene oxide), chemical (some disinfectants)

Question 9

laboratory media are treated with which of the following methods: physical, chemical, therapeutic antimicrobials

Answer 9

physical (autoclave, filtration)

Question 10

skin is treated with which of the following methods: physical, chemical, therapeutic antimicrobials

Answer 10

chemical (antiseptics), therapeutic antimicrobials (topical antimicrobials)

Question 11

mucous membranes are treated with which of the following methods: physical, chemical, therapeutic antimicrobials

Answer 11

chemical (antiseptics), therapeutic antimicrobials (antimicrobials)

Question 12

tissues/organs are treated with which of the following methods: physical, chemical, therapeutic antimicrobials

Answer 12

therapeutic antimicrobials (antimicrobials)

Question 13

moist heat application in the process of sterilization is also known as…..

Answer 13

autoclaving

Question 14

besides autoclaving, (1) and (2) can be used to achieve sterilization of equipment

Answer 14

1- ethylene oxide gas

2- radiation

Question 15

describe the principle of autoclaving

Answer 15

proteins will coagulate as tertiary and secondary structures are destroyed

Question 16

what are the settings required for sterilizing equipment via moist heat/autoclaving

Answer 16

steam at 2 atm at 121C for 15 mins

Question 17

what are the settings required for sterilizing equipment via dry heat

Answer 17

objects exposed to 121C heat for 600 mins (121-171C for 1-6 hrs)

Question 18

(moist/dry) heat penetrates more slowly

Answer 18

dry heat

Question 19

the mechanism of action for dry heat sterilization is….

Answer 19

oxidation

Question 20

boiling is used to destroy (1), but is ineffective in killing (2)

Answer 20

1- vegetative cells (most bacteria and fungi + could activate some viruses)
2- endospores

Question 21

regular pasteurization process is as follows (1) and is used for (2)

Answer 21

1- 63C for 30 mins

2- milk, beer, fruit juices, wine, yogurt

Question 22

HTST or flash sterilization process is as follows (1) and is used for (2)

Answer 22

(high temperature short time)
1- 72C for 15s
2- milk

Question 23

Ultra high temperature sterilization process is as follows (1) and is used for (2)

Answer 23

1- 140C for 3s
2- milk and some juices
(note- no refrigeration required)

Question 24

ionizing radiation uses (1- include λ) which used (2) as its mechanism of sterilization for the following products (3)

Answer 24

1- γ and X-rays (0.1-40 nm)
2- dislodges electrons from atoms to damage DNA and produce peroxides
3- heat or chemical sensitive objects (plastics, tissue grafts, fruits/veggies)

Question 25

non-ionizing radiation uses (1- include λ) which used (2) as its mechanism of sterilization for the following products (3)

Answer 25

1- UV rays (50-400 nm) 2- absorbed by purines/pyrimidines --> forms pyrimidine dimers 3- some foods (nuts, spices)

Question 26

ionizing or non-ionizing radiation penetrates better

Answer 26

ionizing (non-ionizing is limited to surface sterilization)

Question 27

(1) are used to inhibit or kill microorganisms present on inert surfaces through the following non-specific mechanisms: (2)

Answer 27

1- disinfectants 2- damage cell membrane, denature proteins, inactivate enzymes (combined with surfactant for better cleaning)

Question 28

list the ideal disinfectant chracteristics

Answer 28

i- fast acting ii- effective against all types of infectious agents iii- inexpensive, easy to use/obtain iv- no unpleasant smell v- easy to prepare and stable when exposed to environment Note- none have all these features

Question 29

disinfectant effectiveness is measured through the following assays....

Answer 29

- use-dilution test | - filter paper disc method

Question 30

quarternary ammonium compounds are used to clean (1) through (2) mechanism

Answer 30

1- surfaces and equipment | 2- lipid solvent and protein denaturation

Question 31

halogens are used to clean (1) through (2) mechanism

Answer 31

(Cl, I) 1- surfaces and equipment 2- oxidization

Question 32

peroxygens are used to clean (1) through (2) mechanism

Answer 32

(H2O2) 1- surfaces and topical antiseptic 2- oxidization

Question 33

alcohols are used to clean (1) through (2) mechanism

Answer 33

(EtOH, Iso-propyl alcohol) 1- surfaces, equipment, and topical antiseptic 2- lipid solvent and protein denaturation

Question 34

___% of iso-propyl alcohol is used as disinfectant

Answer 34

60-70%, diluted with water

Question 35

antiseptics are determined useful according to its (1) and (2) applications include (3) and (4)

Answer 35

1- antimicrobial activity 2- toxicity to living tissues 3- reduce microorganisms from mucous membrane before surgery 4- remove microorganisms from skin before injection

Question 36

inhibitors of peptidoglycans are used as antibiotics to block (1) and examples include (2)

Answer 36

1- cell wall formation (peptidoglycan cross-linking) in Growing bacteria 2- β-lactam antibiotics: penicillins, cephalosporins

Question 37

antibiotic sensitivity testing is achieved through the following tests....

Answer 37

- Kirby-Bauer sensitivity testing (disk diffusion technique) | - broth dilution technique