unit 2 chap 7

Question 1

sterilization

Answer 1

removal/destruction of all living microbes and spores and viruses (ex. sterilize scapel)

Question 2

disinfection

Answer 2

killing of vegetative pathogens on a surface(inanimate objects); usually w chemicals

Question 3

antisepsis

Answer 3

reduction of pathogens from living tissue(sepsis/asepsis)

Question 4

degerming

Answer 4

removal of transient microbes from skin by physical cleansing or by antiseptic

Question 5

sanitation

Answer 5

reduce overall microbe numbers to safe level

Question 6

bacteriostatic

Answer 6

growth inhibitory; no killing cells

Question 7

bacteriocidal

Answer 7

kill cells but bodies intact

Question 8

bacteriolytic

Answer 8

kill cells no bodies left/ bodies blow up

Question 9

d-value

Answer 9

(decimal reduction time); length of time to get 1log (10^x-1) death

Question 10

what does antimicrobial agents target?

Answer 10

• denaturing proteins and nucleic acids
• plasma membrane disruption
• chemically alter or break nucleic acids

Question 11

physical agents affect on microbes(temperature)

Answer 11

high temperature and pressure
- boiling 10min @ 100C
- steam under pressure
- auto clave: 15psi/121C/15min; sterilization method
pasteurization
- low temp/long time: 63C/30min
- high temp/short time: 72C/15min
- ultrahigh temp: 134*C/1-2sec
dry heat sterilization
- incineration; hotair
cold temperature
- slows bacterial growth and microbial preservation

Question 12

Physical agents affect on mirobes(not temp)

Answer 12

filtration
- membrane filtration for heat labile liquids
- hepa air filter
high pressure
- kills microbes w high pressure
desiccation
- removing water to kill
osmotic pressure
- hypertonic and hypotonic

Question 13

Radiation effect on microbes

Answer 13

nonionizing radiation(uv)
- creates mutations
- doesnt penetrate well
- best for surface disinfection*
ionizing radiation(x rays, gamma, electron beams)
- ionizes water to release OH
- fragments nucleic acids
- penetration radiation
- not easily blocked

Question 14

use-dilution test

Answer 14

• metal rings dipped in test bacteria are dried
• dried cultures are placed in disinfectant for 10 min at 20*C
• rings are transferred to culture to determine whether bacteria survived

Question 15

disk diffusion method

Answer 15

• filter disk soaked in chemical agent
• disk placed on plate w bacteria
• analyze zone of inhibition

Question 16

phenolics

Answer 16

• “hand sanitizer”
• disrupt plasma membrane and denature protiens
• remain active on surfaced after application

Question 17

halogens

Answer 17

• “bleach” and iodine
• alter protein synthesis and membranes

Question 18

alcohols

Answer 18

• require water to denature proteins and dissolve lipids
• ethanol, isopropanol

Question 19

heavy metals

Answer 19

• Ag, Hg, and Cu
• denature proteins
• can be toxic use at low concentrations

Question 20

chemical preservatives

Answer 20

control molds/bacteria in food/cosmetics
- organic acids: alter pH and inhibit metabolism(sorbic acid, benzoic acid)

Question 21

gaseous sterilants

Answer 21

they denature and modify proteins
- for heat sensitive material(plastics)
- ethylene oxide
sterilize objects

Question 22

surface active agents(surfactants)

Answer 22

mimic phospholipid structure and disrupt membrane(detergents)

Question 23

resistance to disinfectants

Answer 23

• at prescription, disinfectants have multiple targets = difficult to mutate against all
• resistance more likely at low concentrations of disinfectant that have single targets

Question 24

most resistant to least resistant to disinfectants

Answer 24

prions
endospores
mycobacteria
cysts of protozoa
vegetative protozoa
gran neg bacteria
fungi and most fungal spores
viruses w/o envelopes
gram pos bacteria
viruses w liquid envelopes