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Microbial control methods used outside of the body

Sterilization

Disinfection

Decontamination

Antisepsis

Disinfection

The destruction/removal of vegetative pathogens but not bacterial endospores, usually inanimate objects

Sterilization

The complete removal/destruction of all viable microorganisms, used on inanimate objects

Antisepsis

chemicals applied to body surfaces to destroy or inhibit vegetative pathogens

Decontamination

the mechanical removal of most microbes

Mechanical removal methods

Filtration of air and liquids

Filtration of air

decontamination

Filtration of liquids

sterilization

Liquids on inanimate objects

Disinfection and sterilization

Liquids on animate objects

Antisepsis

Gases control methods

Sterilization / disinfection

Moist control methods

Steam under pressure and boiling water/pasteurization

Steam under pressure

sterilization

Boiling water

Disinfection

Radiation agents

Ionizing (X-Ray) and nonionizing (UV)

Ionizing

Sterilization

Nonionizing

Disinfection

Asepsis

Free of pathogens/other contaminating organisms

Antiseptics

chemical agents applied directly to exposed body surfaces (skin and mucous membranes), wounds, and surgical incisions to prevent vegetative pathogens

Antiseptics Examples

Preparing the skin before surgical incisions with iodine compounds

Swabbing an open root canal with hydrogen peroxide

Ordinary hand washing with a germicidal soap

A form of decontamination but on living tissues

antisepsis/degermation

Decontamination/Sanitization Examples

soaps, detergents, commercial dishwashers

Higher concentrations

Disinfectant

Lower concentrations

Sanitizer

Disinfection Examples

Bleach, Iodine, Heat

Common uses for Disinfection

boiling food utensils, applying 5% bleach solution to an examining table, immersing thermometers in an iodine solution between uses

Sterilization Examples

heat (autoclave), sterilants (chemical agents capable of destroying endospores)

Cide

Has ability to kill

Static

To stand still

Germicide/microbicide

chemical agents that kill microorganisms

Bactericide

chemical that destroys bacteria except for those at the endospore stage

Fungicide

a chemical that can kill fungal spores, hyphae, and yeasts

Virucide

chemical known to inactivate viruses, especially on living tissue

Sporicide

an agent capable of destroying bacterial endospores

Microbistatic

preventing microbe growth (not direct killing)

Bacteristatic

chemical agents that prevent the growth of bacteria on tissues or on objects in the environment

Fungistatic

chemicals that inhibit fungal growth

Microbial control methods for decides

Critical medical devices, semi critical devices, noncritical devices

critical medical devices

contact with sterile tissues

must be sterilized before use

Semi critical devices

Contact with mucosal membranes

High-level disinfection, preferably sterilized

Noncritical devices

Do not touch the patient or only touch intact skin

Require only low-level disinfection

Metal tools

Autoclaved and re-used

Higher cost and maintenance

Plastic tools

Single-use; disposable

Usually inexpensive

Generates significant amounts of biohazardous waste

Microbial death is determined by

The permanent loss of reproductive capability

Active cells tend to die more quickly than

less metabolically active cells

Factors affecting antimicrobials

number of microbes

types and nature of microbes

environment

concentration and length of treatment time

presence of solvents, organic matter, and inhibitors

Less selective agents

Tend to be effective against wider range of microbes

Selective agents target

only a single cellular component

Cellular targets of physical and chemical agents

Cell wall

Cytoplasmic membrane

Cellular synthetic processes (DNA/RNA)

Proteins

cell wall effects of agents

Blocks wall synthesis or degrade wall

Cytoplasmic membrane effects of agents

Disrupt liquid layer

Creates holes allowing damaging chemicals to enter and important ions to exit

Cellular synthesis effects of agents

Interrupt synthesis of proteins

Prevent replication

Cause mutations

Proteins effects of agent

Denature proteins or block substrates from binding to active site

Cell Wall agent examples

Chemicals, detergents, alcohol

Cytoplasmic membrane agent examples

Detergents/alcoholu

Cellular synthesis agent examples

Formaldehyde, radiation, ethylene oxide

Proteins agent examples

Moist heat, alcohol, phenolics

Most resistant microbial entities

bacterial endospores

Least to most resistant microbial forms

Enveloped viruses

Gram-positive bacteria

No enveloped viruses

Fungi/spores

Gram-negative bacteria

Protozoan trophozoites

Protozoan cysts

Staphylococcus and Pseudomonas

Mycobacterium (causes TB/Hanson's disease)

Bacterial endospores

Prions

Methods of Control: Physical

Heat, cold, desiccation, radiation, filtration, osmotic pressure

Methods of Control: Chemical

Liquids, gases, solids

Moist heat

hot water, boiling water, or steam between 60C and 135C

Primary effect of moist heat

Coagulation and Denaturation of proteins

Stops cellular metabolism

Dry heat

Hot air/open flame: 160C - 1000sC

Moist heat vs dry heat

Moist heat is more effective

Boiling water

30 mins, relied on only for disinfection not sterilization

Pasteurization

Heat applied to liquids

High temp for short time