Microbiology Chapter 7: Disinfectants

Damage to nucleic acids

Alkylating agents are chemical mutagens that alter nucleic acids. Some are carcinogenic/cancer-causing (formaldehyde)

Detergents

Anionic Detergent and Cationic Detergent

Antiseptic

Antimicrobial agent that can be applied to living tissue

Disinfectant

Antimicrobial agent that is applied to inanimate (non-living) objects only

Bactericidal agent/bactericide

Antimicrobial agent that kills bacteria but not necessarily endospores

Sanitizer

Antimicrobial agent used to reduce the number of microorganisms on food handling equipment and utensils

Bacteriostatic agent

Substance that inhibits growth of (but does not kill) bacteria

Viricide

Chemical agent that destroys viruses

Fungicide

Chemical agent that kills fungi

Sterilization

Complete removal of all microorganisms (including endospores) and viruses from an object or surface

Cationic Detergent

Damage to membrane, Ex: dish soap and mouthwash

Anionic Detergent

Damage to membrane, Ex: laundry detergent

Iodine

Damage to membranes, alters protein synthesis, Ex: tincture - in aqueous alcohol, betadine

Damage to proteins

Denaturation of proteins can be permanent (bactericidal) or temporary (bacteriostatic)

Heavy Metals

Denatures proteins, Ex: Silver (Ag), Mercury (Hg), Cu (copper)

Phenols/Phenolics

Disrupt plasma membranes, Ex: Lysol spray

Alcohols

Dissolve lipids (membrane damage), denatures proteins, Ex: Ethanol, Isopropanol (isopropyl alcohol)

Organic acids

Inhibit metabolism, controls growth of molds & bacteria in foods and cosmetics, Ex: sorbic acid, sodium benzoate, calcium propionate

Aldehydes

Inactivate proteins by reacting covalently with functional groups, Ex: glutaraldehyde and Formaldehyde used to sterilize medical equipment

Soaps

Physically washes away bacteria, Ex: body soap

Halogens

Iodine and Chlorine

Effectiveness of antimicrobial agent depends on

Number of microorganisms present, whether they have formed a biofilm, environmental conditions, length of time, degree of microbial resistance

Chemical Food Preservatives

Organic acids, sodium nitrate, and antibiotics

Chlorine

Oxidizing agent that inhibits enzymatic functions, Ex: Hypochlorous acid (HOCl) added to water

Peroxygens

Oxidizing agent, Ex: ozone (O3) and hydrogen peroxide (H2O2), used to sterilize or decontaminate surfaces

Sodium Nitrate

Prevents endospore formation, Ex: in hot dogs, sausage, ham, and bacon

Antibiotics

Prevents endospore formation, prevents mold, Ex: only nisin and natamycin added to dairy

Disinfection

Reducing the number of microorganisms on a surface so that the risk of infection is minimized

Surfactants

Soaps and Detergents

Damage to cell membranes

Some agents, such as surfactants, alter membrane permeability, making membranes leaky