Antiseptic Agent and Concentration

a. Ethyl, isopropyl alcohol - 70% to 90%

b. Iodophors - 1 to 2mg of free iodine/L (1% to 2% available Iodine)

c. Chlorhexidine - 0.5% to 4%

d. Parachlorometaxylenol - 0.5% to 3.75%

e. Triclosan - 0.3% to 2%

E. Conditions Influencing the Effectiveness of Antimicrobial Agent Activity

Population Size

Population Composition

Concentrations or Intensity of Antimicrobial Agent

Duration of Exposure

Temperature

Local Environment

F. Mechanisms of Action

Moist Heat

a. Boiling water (100є C kills only vegetative cells not spores

b. Autoclaves at 121є C to 132є C kills spores by denaturing microbial

proteins

Dry Heat

a. Sterilizes at high temperatures of 171є C for 1 hr, 160єC 2 hr, or 121єC for 16 hr by oxidation of cellular components

b. Effectiveness of sporicidal activity should be monitored with Bacillus subtilis spore strips

Ethylene Oxide

a. A colorless gas, soluble in water and common organic solvents, used to sterilize heat sensitive items

b. Sterilization process is affective by the relative humidity with 30% being ideal, exposure time and temperature

c. Ethylene oxide exerts its sporicidal effects through the alkylation of terminal hydroxyl, carboxyl, amino and sulfhydryl groups resulting in blocking essentialmetabolic processes

Aldehydes

a. Formaldehyde or glutaraldehyde can be used as sterilants or high-level disinfectants

b. The aldehydes exert their effect by alkylation

Oxidizing Agents

a. These agents include ozone, peracetic acid and hydrogen peroxide (H2O2)

b. H2O2at 3 – 6% concentrations kills most bacteria and kills all bacteria including spores at concentrations of 10 – 25%

c. The active oxidant is the free hydroxyl radical following decomposition of the hydrogen peroxide

d. Used to disinfect plastic implants, contact lens and surgical protheses

Halogens

a. Compounds containing iodine or chlorine

b. Iodine acts by precipitating proteins and oxidizing essential enzymes

c. Hypochlorites interact with cytoplasmic components to form toxic compounds interferring with metabolism

Phenolic Compounds

a. Germicides rarely used as disinfectants

b. Not sporicidal or poorly active against non-lipid containing viruses

c. Acts by disrupting lipid containing membranes

Quaternary Compounds

a. Consist of 4 organic groups covalently linked to nitrogen

b. Germicidal activity is determined by the nature of the groups with C chains of 8 –18 having the greatest activity

c. Act by denaturing cell membranes to release the intracellular components