Micro Physical and Chemical Agents of Disinfection Learning Goals

what are 4 characteristics that a good chemical agent should be

1. inexpensive

2. fast-acting

3. stable during storage

4. capable of controlling microbial growth while being harmless to humans, animals, and objects

high level germicides kill what

all pathogens, including endospores

what are high level germicides used to disinfect

invasive instruments ex: scalpel

what do intermediate level germicides kill

fungal spores, protozoan cysts, viruses, and pathogenic bacteria

what are intermediate level germicides used to disinfect

instruments that contact mucous membranes but are non-invasive

what are low level germicides used to kill

vegetative bacteria, fungi, protozoa, and some viruses

what are low level germicides used to disinfect

items that contact skin only

what is the appropriate level germicide for a scalpel to be used in invasive surgery

high

what is the appropriate level germicide for a blood pressure cuff

low

what is the appropriate level germicide for a needle used for injection

high

what is the appropriate level germicide for anesthesia equipment

intermediate

what are phenols and phenolics commonly used in

health care setting, labs, and homes

what is an example of a phenol (2)

lysol and triclosan

phenols are effective in presence of ___ ___ and remain active for ___ time

organic matter; prolonged

what level are phenols

intermediate to low level

phenols work by (2)

denaturing proteins and disrupting cell membranes

alcohols are what level of disinfectant

intermediate level

alcohols work by (2)

denaturing proteins and disrupting cytoplasmic membranes

are alcohols or soaps more effective in removing bacteria from hands

alcohols

swabbing skin with __% alcohol prior to injection removes most microbes

70

swabbing skin with alcohol helps remove microbes most by

determine, not chemical action

what 4 elements do halogens include

iodine, chlorine, bromine, fluorine

what level disinfectant are halogens

intermediate level

how do halogens work

damage proteins by denaturation

what are three oxidizing agents

peroxides, ozone, and paracetic acid

how do oxidizing agents kill

by oxidation of microbial enzymes

what level are oxidizing agents

high level and antiseptics

hydrogen peroxide can ___ and ___ surfaces

disinfect; sterilize

is hydrogen peroxide useful for treating open wounds?

no because of catalase activity

what do you use ozone treatment for

drinking water

___ ___ is effective sporicide used to sterilize equipment

peracetic acid

surfactants reduce ___ ___ of solvents

surface tension

what are two examples of surfactants

soap and detergents

soaps have ___ and ___ ends

hydrophilic; hydrophobic

surfactants are good ___ agents but not ___

degerming; antimicrobial

detergents are ___ charged ___ surfactants

positively; organic

what do quats stand for

quaternary ammonium compounds

quats are what level disinfectant

low level

how do quats work

they disrupt the cellular membrane

what are quats ideal for

many medical and industrial applications

how do heavy metals work

ions denature proteins

what level are heavy metals

low level

are heavy metals bacteriostatic or bactericidal

bacteriostatic

what is used to be used to prevent blindness

1% silver nitrate

thimerosal is used to

preserve vaccines

copper controls

algal growth

how do gaseous agents work

denaturing proteins and DNA by cross-linking functional groups

where are gaseous agents used

hospitals and dental offices

what is an example of a gaseous agent

ethylene oxide

disadvantages of gaseous agents

can be hazardous to people, often highly explosive, extremely poisonous, and potentially carcinogenic

gaseous agents are used in ___ ___ to sterilize items

closed chambers

antimicrobial enzymes act against ___

microorganisms

human tears contain

lysozyme

lysozymes digest

peptidoglycan cell wall of bacteria

lysozyme is used to reduce the number of bacteria in

cheese

prionzyme can remove___ on medical instruments

prions

vegetative bacterial cells are killed by what levels of disinfectant

high, intermediate, and low

mycobacteria are killed by what levels of disinfectant

high and intermediate

spores are killed by what levels of disinfectant

high level

fungi are killed by what levels of disinfectant

high, intermediate, and low

viruses are killed by what levels of disinfectant

high, intermediate, and sometimes low

3 examples of high level disinfection

ethylene oxide, glutaraldehyde, and formaldehyde

2 examples of intermediate level

phenols and halogens

2 examples of low level disinfectants

alcohols and quats

what does the phenol coefficient evaluate

efficiency of disinfectants and antiseptics

what does the phenol coefficient compare

to phenol an agent’s ability to control microbes

a phenol coefficient greater than 1.0 indicates what

an agent is more effective than phenol

what is sterilization

destruction of all living cells, spores, and/or viruses

what is disinfection

removal of disease-causing microorganisms from inanimate surfaces

does disinfection always result in sterilization

not always

what is antisepsis

removal of disease-causing microorganisms from living tissues such as skin or mucous membrane

does antisepsis result in sterilization

not always

what is sanitation

reduction of microbe numbers to “safe” levels to meet public health standards

cidal agents have ___ effects

lethal

bactericidal agents ___ bacteria

kill

static agents ___ or ___ metabolism/reproduction, but are not necessarily lethal

slow; stop

bacteriostatic agents ___ bacterial growth

inhibit

the cell wall maintains the ___ of a cell

integrity

when the cell wall is damaged, it cannot prevent the cell from ___ due to osmotic effects

bursting

the cytoplasmic membrane contains ___ and controls passage of ___ into and out of the cell

cytoplasm; chemicals

when the cytoplasmic membrane is damages what happens

cellular contents leak out

viral envelope is responsible for what

attachment of virus to its target cell

damage to the viral envelope interrupts ___ ___

viral replication

can enveloped or non-enveloped viruses better tolerate harsh conditions

non-enveloped

protein function depends on ___

3D shape

what can denature proteins (2)

extreme heat or certain chemicals

what 3 things can destroy nucleic acids

chemicals, radiation, or heat

5 factors that affect the efficiency or choice of antimicrobial measures

1. site to be treated

2. relative susceptibility of microbe

3. environmental conditions

4. initial population size

5. duration of exposure to lethal agent

can harsh chemicals and extreme heat be used on humans, animals, or fragile objects

no

procedures that penetrate the outer defenses of the body require ___

sterilization

procedures that contact only the surface of a mucous membrane or skin require

disinfection

what microbe is the most resistant

prions

what microbe is the most susceptible

enveloped viruses

the presence of organic material (blood, feces) can ___ antimicrobial action

inhibit

do disinfectants work better at warmer or cooler temperatures

warmer

do disinfectants work better under basic or acidic conditions

acidic

a higher initial population size takes ___ time for a disinfectant to work

more

what is the d-value

the time required to kill 90% of the cells (time required for viable cell count to drop by one log unit)

high temperatures do what (3)

denature proteins, interfere with integrity of cytoplasmic membrane and cell wall, and disrupt structure of nucleic acids

what is the thermal death point

the lowest temperature that kills all microbes in a set amount of time