4.5 Microbial Control Methods

Flashcards covering key concepts related to microbial control methods and the chemicals used.

Disinfection

The destruction or removal of vegetative pathogens but not bacterial endospores, usually on inanimate objects.

Sterilization

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

Antiseptic

The process of applying antiseptic substances to living tissues to reduce the risk of infection, sepsis, or putrefaction.

Alcohols

Optimum concentration is 60-95% and kills most vegetative bacteria/fungi, some viruses with ~30-60 second wash; ineffective against endospores and most naked viruses

• Ethanol, Isopropanol

• Disrupt cell membranes, denature proteins

Surfactants

Kills most bacteria/fungi and enveloped viruses although generally ineffective against endospores, naked viruses, and acid-fast bacteria; effective at removing dirt and oil from surfaces

• Benzalkonium chloride, Quaternary Ammonium Compounds (Quats)

• Disrupt cells membrane

Phenols

Stable and active for long periods after use, effective against many bacteria and fungi; can be corrosive on skin/mucus layers, some health/superficial concerns regarding some uses (i.e. baby bottles)

• Phenol (carbolic acid), Chloro-benzylphenol, Thymol

• Disrupt cell membranes, denature proteins

Biguanides

Broad spectrum yeast and bactericidal disinfectant with prolonged bacteriostatic effect; relatively minimal side effects and used in many cosmetics, pharmaceuticals

• Chlorhexidine, polyaminopropyl biguanide (PAPB), Proguanil

• Disrupt cell wall, cell membrane

Halogens

Broad spectrum disinfectant, kills most bacteria and viruses; sterilant at high concentrations/time

• Betadine, Chlorine, Sodium fluoride

• Denature proteins, oxidize cellular components

Oxidizing Agents

Kills most vegetative bacteria/fungi and some viruses and long/concentrated exposure demonstrates broad-spectrum efficacy against viruses, bacteria, yeasts, and bacterial spores; used to sterilize surfaces, tools, rooms (VHP – vapor H.P.) yet still safe to use on the skin

• Hydrogen Peroxide, Activated Oxygen (Ozone), Potassium permanganate

• Denature proteins, oxidize cellular components

Heavy Metals

Largely effective for external infections and often coats medical equipment with internal bodily access

• Silver, Mercury, Copper, Selenium, Zinc

• Denature proteins

Aldehydes

Broad spectrum and highly effective antimicrobial agent including endospores and viruses, often found in sterilants; effective tissue preservative, used in vaccines to inactivate toxins/organisms

• Crosslink nucleic acids and proteins

• Formalin, Formaldehyde,

Gaseous Agents

Used to sterilize although limited surface penetration, generally used for delicate surgical equipment due to minimal damaging effects

• Crosslink proteins and DNA

• Ethylene oxide

Chemicals that are sterilants

• Halogens

• Oxidizing Agents

• Aldehydes

• Gaseous agents

NOT Antiseptic Chemicals

• Heavy Metals

• Aldehydes

• Gaseous Agents