Microbiology CHapter 7

Question 1

Microbial Control Terminology? Sepsis, Asepsis and Sterilzation

Answer 1

Sepsis - microbial contamination
Asepsis - absence of significant contamination
Sterilization - removing all microbial life

Question 2

Microbial Control Terminology? Commercial Disinfection Disinfection and antisepsis

Answer 2

Commercial sterilization - killing C. botulinum endospores
Disinfection - removing pathogens
Antisepsis - removing pathogens from living tissue

Question 3

Microbial Control Terminology?Degerming, Sanitization and Biocide/germicide

Answer 3

Degerming - removing microbes from a limited area
Sanitization - lowering microbial counts on eating utensils
Biocide/germicide - killing microbes

Question 4

Effectiveness of Treatment (and therefore Death Rate) depend on?

Answer 4

Number of microbes
Environment 
Organic matter
Temperature
Biofilms
Time of exposure
Microbial characteristics

Question 5

Actions of MIcrobial Control Agents?

Answer 5

Alteration of membrane permeability
Damage to proteins
Damage to nucleic acids

Question 6

Decreasing order of resistance of microorganisms to chemical biocides.

Answer 6

most- prions(infectious proteins) , endospores of bacteria, mycobacteria( waxy lipid, mycolic acid) , cysts of protozoa, vegetative protozoa( strong like endosopre), gram neg bacteria, fungi and fungal spores, viruses without envelope, gram pos bacteria, viruses with lipid envelopes. with envelope easiest to kill.

Question 7

Physical or Chemical methods of Microbial Control?Heat(moist,dry,pasteurization)filterization,low temperature,pressure(osmotic and high) dessication

Answer 7

physical

Question 8

what are radiation methods for microbial control?

Answer 8

Ionizing radiation (X rays, gamma rays, electron beams)
Ionizes water to release OH•
Damages DNA
Nonionizing radiation (UV, 260 nm)
Damages DNA
Microwaves kill by heat; not especially antimicrobial

Question 9

Principles of Effective Disinfection

Answer 9

Concentration of disinfectant
Presence of organic matter
pH
Time of exposure

Question 10

Dilution Test

Answer 10

Metal Rings 20 degrees for 10 minutes

Question 11

Mercury,Phenolics,Bisphenols,Quats,Chlorines,Iodines,Alcohols,GLutaraldehyde and chlrohexidine

Answer 11

Chemical Agents for microbial growth control

Question 12

mechanism of phenolics for microbial growth control and biguanides

Answer 12

Disrupt plasma membrane, examples Lister like lysol for phenolics and chlorohexidine like betadine

Question 13

Halogens function of iodine and chlorine on microbe death

Answer 13

Iodine
Alters protein synthesis and membranes
Tinctures: in aqueous alcohol
Iodophors: in organic molecules
Chlorine
Oxidizing agents
Bleach: hypochlorous acid (HOCl)
Chloramine: chlorine + ammonia

Question 14

alchols require water for microbial death control to

Answer 14

denature proteins and dissolve lipids

Question 15

Heavy Metals function by

Answer 15

denaturing proteins,Silver nitrate may be used to prevent gonorrheal ophthalmia neonatorum
Silver sulfadiazine used as a topical cream on burns
Copper sulfate is an algicide

Question 16

types of surface active agents or surfacants

Answer 16

soap = degerming, acid anionic detergent = sanitize,cationic detergents =Bactericidal, denature proteins, disrupt plasma membrane

Question 17

Organic acids
Inhibit metabolism
Sorbic acid, benzoic acid, and calcium propionate
Control molds and bacteria in foods and cosmetics
Nitrite prevents endospore germination
Antibiotics
Nisin and natamycin prevent spoilage of cheese

Answer 17

are mechanisms of chemical food preservatives

Question 18

aldehydes function by

Answer 18

Inactivate proteins by cross-linking with functional groups (–NH2, –OH, –COOH, –SH)
Use: medical equipment

Question 19

Gaseous Sterilants

Answer 19

Denature proteins
Used with heat-sensitive material
Example: Ethylene oxide

Question 20

Free radicals destroy microbes

Used for sensitive tubular instruments

Answer 20

use of plasmas

Question 21

CO2 with gaseous and liquid properties

Used for medical implants

Answer 21

supercritical fluids

Question 22

peroygens function by

Answer 22

Oxidizing agents
Used on contaminated surfaces
O3, H2O2, peracetic acid