chap 7

Question 1

sepsis =

Answer 1

microbial contamination

Question 2

Asepsis =

Answer 2

absence of significant contamination

Question 3

Aseptic surgery techniques prevent ______________.

Answer 3

microbial contamination of wounds

Question 4

sterilization =

Answer 4

removing all microbial life

Question 5

commercial sterilization =

Answer 5

killing C.botulinum endospores

Question 6

disinfection =

Answer 6

removing pathogens

Question 7

antisepsis =

Answer 7

removing pathogens from living tissue

Question 8

degerming =

Answer 8

removing (wiping) microbes from limited area

Question 9

sanitization =

Answer 9

lowering microbial counts on eating utensils

Question 10

biocide/germicide =

Answer 10

killing microbes

Question 11

bacteriostasis =

Answer 11

inhibiting, not killing (doesn’t metabolise) microbes = low temp

Question 12

microbial control agent:

Answer 12

• alteration of cell walls and membranes
• cell wall maintains integrity of cell
• when damaged, cells burst due to osmotic effects
• cytoplasmic membrane controls passage of chemicals into and out of cell
• when damaged, cellular contents leak out
• non enveloped viruses more tolerant of harsh conditions: outer coat=protein held tighter together

Question 13

antimicrobial agent:

Answer 13

damage to proteins and nucleic acids
- protein function depends on 3-D shape
- extreme heat or certain chemicals denature proteins
chemicals, radiation, and heat can alter/destroy nucleic acids
- produce fatal mutants
- halt protein synthesis through action on RNA (2 ways)

Question 14

DRT

Answer 14

Decimal (10) Reduction Time = minutes to kill 90% of a population at a given temp.

Question 15

Microbial Exponential Death Rate

Answer 15

rapid, very fast death rate

Question 16

effectiveness of treatment depends on:

Answer 16

• number of microbes (more bacteria=takes time to get rid of)
• environment (organic matter, temp, biofilms)
• time of exposure
• microbial characteristics

Question 17

physical method of control

Answer 17

• temp
• desiccation (osmotic pressure ad lyophilization)
• filtration (air and liquids)
• radiation (ionizing and non-ionizing)

Question 18

thermal death point (TDP) =

Answer 18

lowest temp at which all cells in a culture are killed in 10min.

Question 19

thermal death time (TDT) =

Answer 19

time during which all cells in a culture are killed

Question 20

moist hear denature the proteins. Autoclave=

Answer 20

steam under pressure 121C for 15 min. 15 psi 1-1.5hr

steam must contact item’s surface

Question 21

pasteurization

Answer 21

- reduce spoilage of organisms and PATHOGENS
equivalent treatments:
- 63C for 30min.
- high-temp short time 70C for 15 sec
- ultra-high-temp 140C for

Question 22

dry heat sterilization

Answer 22

kills by oxidation:

• dry heat
• flaming
• incineration
• hot-air sterilization
• used for materials that cannot be sterilized with moist hear: oil, petroleum jelly, wax

Question 23

filter sterilization

Answer 23

used for heat sensitive liquids

Question 24

Filtration:

Answer 24

• HEPA removes microbes >0.3 mm
• membrane filtration removes microbes >0.22mm
• HEPA filters are found in hospital isolation rooms, operating theaters, industrial clean room

Question 25

physical method of microbial control

Answer 25

• low temp. inhibits microbial growth
• desiccation prevents metabolism, no free water
• osmotic pressure causes plasmolysis

Question 26

radiation:

Answer 26

• ionizing radiation (X-rays, gamma rays, electron beams)
• nonionizing radiation (UV, 260mm)
• microwaves kill by heat, not especially antimicrobial

Question 27

effective disinfection:

Answer 27

• concentration of disinfectant
• organic matter
• pH
• time

Question 28

phenol & phenolics:

Answer 28

• disrupt plasma membrane
• effective in presence of organic matter
• Lysol, Triclosan

Question 29

Bisohenols

Answer 29

• disrupt plasma membrane

- Hexachlorophene, Triclosan

Question 30

Biguanides

Answer 30

• chlorhexidine

- disrupt plasma membrane

Question 31

halogens

Answer 31

iodine
- Tinctures: in aqueous alcohol
- Iodophors: in organic molecules
- alter protein synthesis and membranes
chlorine
- bleach: hypochlorous acid (HOCI)
- chloramine: chlorine + ammonia
- oxidizing agents

Question 32

alcohols

Answer 32

ethanol, isopropanol

• denature proteins, dissolve lipids
• require water

Question 33

heavy metals

Answer 33

• Ag, Hg, Cu

- oligodynamic action

Question 34

surface-active agents/surfactants

Answer 34

soap - degermiing
acid-anionic detergents - sanitizing
quaternary ammonium compounds (cationic detergents) - bactericidal, denature proteins, disrupt plasma membrane

Question 35

aldehydes

Answer 35

inactivate proteins by cross-linking with functional groups

use: medical equipment *

Question 36

gaseous sterilants

Answer 36

denature proteins
use: heat-sensitive material
- ethylene oxide
- used in hospitals and dental offices
- disadvantages
can be hazardous to people
often highly explosive
extremely poisonous
potentially carcinogenic (cancer causing)

Question 37

plasma

Answer 37

free radicals destroy microbes

use: tubular instruments *

Question 38

supercritical fluids

Answer 38

• CO2 with gaseous and liquid proteins
• supercritical liquid make great solvents; used in number of industrial applications=decaffeinating coffee, dry-cleaning
• used for food preservation and are now used to sterilize tissues (bones, ligaments, tendons) that are to be surgically implanted.

Question 39

peroxygens

Answer 39

oxidizing agents
use: contaminated surfaces
= O3, H2O2, per acetic acid