Control of Microbes including antibiotics

Question 1

Bacteriostatic

Answer 1

Stop/inhibit bacterial growth (reversible/does not kill bacteria)

Question 2

Bactericidal

Answer 2

Kills bacteria (irreversible)

Question 3

Sterilization

Answer 3

destruction of all forms of microbial life and acellular entities, such as endospores.

Question 4

Disinfection

Answer 4

destruction of vegetative cells (doesn’t impact endospores) (bleach is an example of disinfection)

Question 5

Antsepsis

Answer 5

disinfection of living tissue, ex: hydrogen peroxide (and not all disinfections are antisepsis)

Question 6

Degerming

Answer 6

removal of microbes from a limited area (quick cleaning of bacteria)

Question 7

Sanitization

Answer 7

lowering microbial counts to safe public health levels.

Question 8

What is D-value/decimal reduction time?

Answer 8

decimal reduction time (D-value) is time required to kill 90% of microbes or spores in a sample under the conditions.

Death of a microbe equals the loss of the ability to grow and reproduce (which gradually happens over a period of time).

Question 9

Autoclave

Answer 9

steam under pressure increases temperature and also kills endospores and viruses that survive boiling.

Question 10

Pasteurization

Answer 10

reduces microbial load, kills pathogens (doesn’t kill of all microbes just a large amount) and does not sterilize.

Question 11

Incineration

Answer 11

direct flaming of the loop in the laboratory and disposal of biological materials.

Question 12

Hot air oven

Answer 12

for materials unable to withstand steam (used to prevent exposure to steam and need a linger time for sterilization).

Question 13

Autoclave is not preferred to use than hot air oven, True or False?

Answer 13

False autoclave is preferred over hot air oven.

Question 14

What are the two common pore sizes for membrane filtration of liquid samples?

Answer 14

the two common pore sizes for membrane filtration of liquid samples are 0.2Mm and 0.45Mm which helps to get rid of bacteria.

Question 15

Filtration

Answer 15

separates bacteria from liquid, filter sample through a membrane and is used for liquids that can’t be autoclaved

Question 16

Ultrafiltration

Answer 16

a gram-negative microbes killed by autoclaving.

Question 17

What is the difference between the use of ionizing and non-ionizing radiation in control of microbial growth?

Answer 17

Ionizing and non-ionizing both damage DNA. But ionizing has a stronger penetration power (wavelength <1nm (gamma rays, X-rays)) while has a poor penetrating power used for surface sterilization/used to sterilize petri plate (wavelength >1nm (UV light))

Question 18

What are containing compounds and alcohols that are used in chemical control of microbes?

Answer 18

Halogen (Bromine Br, Chlorine Cl, Astatine At, Iodine I, Fluorine F, Tennessine Ts) and chlorine and iodine are halogens used in chemical to control microbes.
Chlorine-traditionally for disinfecting drinking water (can kill spores)
Iodine-very effective germicide (antiseptic)
Ethanol and isopropyl alcohols are alcohol used in chemical control of microbes.

Question 19

What is the difference between natural, synthetic, and, semisynthetic antibiotics?

Answer 19

Natural antibiotics- compete with other microbes.
Synthetic antibiotics- human made, synthesize to use as treatment.
Semisynthetic- makes changes to chemical structure.

Question 20

What are narrow spectrum vs broad spectrum antibiotics?

Answer 20

Narrow spectrum-effective only against a few types of microbes.
Broad spectrum- effective against many types.

Question 21

Minimal inhibitory concentration (MIC)

Answer 21

lowest concentration of an antibiotic that inhibits growth of a test organism.

Question 22

Minimal bactericidal concentration (MBC)

Answer 22

lowest concentration of antibiotic that kills a test organism.

Question 23

List the mode of action for these antibiotics: Penicillin, Polymyxin, Quinolones, Rifampin, Actinomycin, Tetracycline, Isoniazid, and Trimethoprim.

Answer 23

Inhibition of cell wall synthesis- penicillin, cephalosporins, bacitracin, vancomycin.

Inhibition of protein synthesis- tetracyclines, chloramphenicol, erythromycin, and streptomycin.

Inhibition of nucleic acid replication and transcription- quinolones, actinomycin, and rifampin.

Cell membrane inhibitors- polymyxins

Enzyme inhibitors- trimethoprim and isoniazid

Question 24

List some ways in which antibiotics are overused/misused.

Answer 24

Overuse of antibiotics for non-medical purposes.
Overuse of antimicrobial compound containing products.

Question 25

What are the 4 mechanisms of antibiotic resistance discussed in class?

Answer 25

• Inhibitors of DNA replication- resistance is due to efflux pumps, which membrane proteins that expel/pumps antibiotic out of the cell (expel the antibiotic before it reaches its target).
• Inhibitors of protein synthesis- bugs may modify antibiotic-binding site on ribosome to become resistant and some bugs prevent penetration of drug (drug is block from entering the microbial cell).
• Bacteria quickly modify the target enzyme to become triclosan-resistant.
• These resistance mechanisms may render the organisms resistant to other antibiotics with a similar target.