ch 11 - physical/chemical agents of microbial control

microorganisms can be destroyed/reduced how?

physical, chemical, mechanically

what can primary targets/microorganisms consist of?

vegetative, endospores, fungal, viruses/prions, etc

what are prions

misfolded proteins that affect normal proteins

microbes of high resistance

prions + bacterial endospores

microbes of moderate resistance

m. tuberculosis, staph. aureus, protozoan cysts

microbes of least resistance

most vegetative cells, fungal spores, viruses, protozoan trophozoite

what about endospores?

really resistant; require more of everything

sterilization

destroys all microorganisms (viruses + endospores)

disinfection

destroy vegetative pathogens; inanimate objects

antiseptic

disinfectants can be used on body surfaces

sanitization

mechanically removes microbes

factors that affect death rate

time, load, resistance, agent type

mode of action

way drug affects microbes at the cellular level

what happens when cell wall is targeted?

wall becomes fragile + lyses

what factors can disturb cell wall integrity?

some antimicrobial, detergents, alcohol

what happens when cell membrane is disturbed?

phospholipid bilayer loses integrity

what are some agents that affect cell membrane?

detergent surfactants

what happens when protein + nucleic acid synthesis is affected?

replication prevention, transcription, translation, etc.

antimicrobial agents can affect central DOGMA which is?

dna to rna to protein

what are some agents that affect protein/nucleic acid synthesis

chloramphenicol, ultraviolent radiation, formaldehyde

what happens when proteins are interfered by agents?

protein disruption/denature

what are some agents that can alter with proteins?

alcohols, phenols, acids, heat

if you are washing your hand with hand soap, you are accomplishing?

antisepsis + sanitization

moist heat

low temp + short exposure time

moist heat results in?

coagulation + protein denaturation

dry heat

moderate to high temp

what does dry heat result in?

dehydration, alters protein structure

an incineration is an example of?

dry heat

steam under pressure is an example of?

sterilization

autoclave must be set to...

15 psi, 121 c, 10-40mins

autoclave mode of action

protein denaturation + membrane/dna destruction

what temp. is needed for boiling to destroy non-spore forming pathogens? (disinfection)

100 c, 30 mins

pasteurization

heat; kills agents without destroying food flavor/value

pasteurization batch method

63-66 c, 30 mins

Pasteurization flash method

71.6 c for 15 seconds

difference between dry heat and moist heat

dry heat used higher temp.

dry ovens (type of dry heat) are known to?

coagulate proteins; 150-180 c.

cold methods consist of?

microbiostatic, desiccation, lyophilization

microbiostatic function

slows microbe growth; food, media, cultures

example of microbiostatic

refrigeration 0-15 C + freezing

desiccation (dehydration) is known to?

remove water from cells > temporarily stops growth

lyophilization

freeze drying/preservation

which of the following accomplishes microbiocidal effects?

incineration

ionizing radiation

electrons leave orbit, breaks dna

examples of ionizing radiation

gamma rays, X-rays, cathode rays

what is ionizing radiation used for?

sterilize medical supplies + food product

nonionizing radiation

low power, excites atoms, bends dna

example of nonionizing radiation

uv light, sterilizing air/water

filtration

microbe removal, gas/liquid through filter

when is filtration used to sterilize?

heat sensitive liquids + air in hospital units

high-level germicides

kill endospores; sterilants

high level germicides cannot be used for?

sterile body tissue

intermediate level

kill fungal spores, tubercle bacillus, viruses

when are intermediate level germicides used?

disinfect devices in contact w mucous membranes

low-level germicides

vegetative cells

what do low-level germicides clean?

clean surfaces that touch skin

factors that affect germicidal chemical activity?

material treated, contamination, time, germicide strength

ethyl/isopropyl is used in which solution percentages?

50-95%

alcohol mode of action

dissolves membrane lipids + coagulates proteins

alcohols mainly affect?

vegetative cells + fungi; intermediate

iodine

one of oldest + most effective antiseptics

iodine mode of action

alters plasma membranes

iodine is known to work against?

all bacteria, many endospores, fungi, viruses

tincture

iodine + alcohol

iodophor

iodine + organic carrier molecule

example of iodine that is still used today?

betadine

hydrogen peroxide mode of action

damage protein + dna

hydrogen peroxide is used for?

antiseptic (low), sporicidal (strong solution)

quaternary ammonia compounds (quats) mode of action is?

alters membrane permeability

quats affects?

bacteria, fungi; low level

soaps mode of action

mechanically remove soil + grease w microbes

which of the following accomplishes antimicrobial effects by creating nucleotide dimers?

UV light

in nonionizing radiation, UV light creates?

pyrimidine dimers; interfere replication