Disinfectants – treat non-living material Antiseptics – treat the surface of a living organism Chemotherapeutic agents – used within a living organism; an example is antibiotics

Classes of Antiseptics and Disinfectants 1 Alcohols Straight chain – ethyl and isopropyl. Both are most effective at about 70% concentration Phenols (carbon ring); Lysol, hexachlorophene

Classes of Antiseptics and Disinfectants 2 Heavy Metals Mercury compounds; mercurochrome Silver compounds; silver nitrate used in newborn’s eyes to prevent possible gonorrhea infection

Classes of Antiseptics and Disinfectants 3 Halogens Chlorine compounds: bleach (Chlorox) used as disinfectant; also used to clean drinking water Iodine compounds: – Tincture of iodine used as antiseptic – Betadine used as a disinfectant or as an antiseptic, kills spores, used to pretreat an area in which an incision will be made

Classes of Antiseptics and Disinfectants 4 Soaps and Detergents Relatively weak toxic effect, but effectively removes microbes from surfaces May disrupt cell membranes

Classes of Antiseptics and Disinfectants 5 Peroxides Hydrogen peroxide is a toxic oxygen product. Has been used on the skin and as a mouthwash.

Mode of action of Disinfectants Most denature proteins Some produce toxic oxygen products, in an oxidative burst: bleach and hydrogen peroxide.

Spores are most resistant to chemical agents Mycobacteria are relatively resistant, due to waxy wall, which prevents penetration The outer membrane of Gram - bacteria provides a barrier to penetration of some chemicals, so these are more resistant than Gram + Pseudomonas (Gram -) is especially resistant because it can use many uncommon carbon sources for growth, including some antiseptics