Chapter 11

Sterilization

destruction of all microbial life

Disinfection

destroy most microbe life

Antisepsis

disinfection but on a living surface

Decontamination

mechanical removal of most microbes from a living or nonliving

Bacterial endospores are

18 times harder to destroy than vegetative cells

Disinfection destroys vegetative but not

endospores

Bactericide

chemical that destroys vegetative bacteria

Fungicide

kills fungi

sporicide

destroys bacterial endospores

Bacteriostatic

prevent the growth of bacteria on tissues or objects

Sanitization

cleansing that removes microbes and also any debris (like lipstick on a fork)

Critical

expected to come in contact with sterile tissues, must be sterilized (syringe)

Semicritical

come in contact with mucous membranes (endoscopy tube), high-level disinfection

Noncritical

do not touch patient, low level decontamination (blood pressure cuffs)

Microbe death

the permanent loss of reproductive capability

Active microbes tend to die

faster than inactive

Factors of microbe death

quantity of microbes, kind of microbe, type of growth, temperature and pH of environment, concentration of cleaning product, mode of action of agent, presence of solvents like blood

Mode of action

antimicrobial agent's adverse effect on cells

Cellular targets of agents

cell wall, cell membrane, DNA or RNA, and proteins

Surfactants

bind to membrane and "open it up", then seep into cell and kill it

Agents that affect protein and nucleic acid synthesis

binds to ribosomes and stop peptides from forming

Some antimicrobials denature

proteins

Methods of controlling microbes

physical and chemical

Moist heat operates at

lower temperatures and shorter exposure times than dry heat to kill

Bacterial endospores have the

most resistance to heat

Thermal death time

the shortest length of time to kill microbes at a specific temperature

Thermal death point

lowest temperature to kill all microbes in 10 minutes

Tinctures

solutions dissolved in pure alcohol or water-alcohol mixtures

Levels of chemical decontamination

high, intermediate, adn low

High Levels of chemical decontamination

kill endospores, can sterilize. Used on critical items, not heat-sterilizable and are intended to enter body tissues if needed

Intermediate Levels of chemical decontamination

kill fungal spores, pathogens and viruses. Can disinfect semicritical items

Low Levels of chemical decontamination

clean non critical materials

Factors affecting the usefulness of a germicide

nature of microbes, nature of the material being treated, degree of contamination, time of exposure, strength and chemical action of germicide

Modes of germicides

cellular, nucleic acids, cell membrane

Large amounts of organic matter can

hinder the penetration of a disinfectant

Germicide agents

halogens, heavy metals, alcohol, phenolic compounds, oxidizers, aldehydes, detergents, and gases

Halogens

fluorine, bromine, chlorine, iodine

iodophors

complexes of iodine and alcohol, allows slow release of free iodine and increases the degree of penetration

Phenol

poisonous from coal tar. Major use until other pheolics were made

Alcohol

colorless with one or more -OH groups.

Hydrogen peroxide

colorless caustic liquid, decomposes into water and oxygen gas in the presence of light, metals or catalase. Bactericidal, virucidal, fungicida, and even sporicidal

Quaternary ammonium compounds are effective against

some gram-positive bacteria, viruses, fungi, and algae, function best in alkaline solutions, a low-level disinfectant

Only ___ metals have significance as germicides

mercury and silver

Oligodynamic action

antimicrobial effects in small amounts

Mercury, silver, and other metals exert microbicidal effects by

binding onto functional groups of proteins and inactivating them, stopping metabolism

Aldehydes most often used as microbial control

glutaraldehyde and formaldehyde

Ethylene oxide

colorless, is a gas at room temperature, explosive in air. Blocks DNA replication in enzymatic actions

Low or high pH can

be used as microbes inhibitors but are corrosive and can be hazardous

Some essential oils are good for microbial inhibition especially

phenolics