Disinfectants

Which should you choose?

The choice of the appropriate disinfectant is critical for any work involving a biohazardous agent. A number of different classes of disinfectants are available including phenols, quaternary ammonium compounds, chlorhexidine compounds, halogen compounds, alcohols, aldehydes, etc. The decision as to the most appropriate agent requires a knowledge of both the organism's susceptibility to the agents and the type of substrate that will require decontamination. Agents offering the lowest potential for personnel or environmental toxicity should be used whenever possible.

Each laboratory must prepare a specific protocol for handling the decontamination of work surfaces, equipment, and spills. The CDC recommends the use of a 1:10 dilution of household bleach (5,250 ppm sodium hypochlorite final dilution) in neutral water with a 20 minute contact time for the decontamination of blood spills. Other disinfectant solutions may be more appropriate for other situations.

The attached table outlines examples, usage tips, advantages, and disadvantages of common disinfectants.

Disinfectants – Selection and Use Table

Type Dilution Examples Tips for Use Advantages Disadvantages Chlorine 1:10 (~5000ppm Clorox, -Store diluted solution in sealed -Relatively nontoxic -Inactivated by organic material such as blood, do not use Cmpds. free chlorine) household container protected from light -Low cost at less than 1:10 dilution bleach, -Use to decontaminate liquid culture -Effective with detergents -Corrosive Bleach-Rite media, for spill cleanup, and to wipe -Fast acting -Irritates mucus membranes, eyes, and skin down work surfaces -Broad spectrum effectiveness -No residual activity on surfaces -Can damage clothing -Contact Time from 10-30 minutes -Deodorizing/sanitizing -Produces toxic chlorine gas if mixed with acids or ammonia compounds -Prolonged deterioration on standing Alcohols -Dilute to 70% in Isopropanol, -Use to clean instruments and wipe -Non-corrosive -Can have reduced effectiveness in organic material, does water, (looses Purel, down interior of Biological Safety -Effective with detergent not penetrate organic material effectiveness at Rubbing Cabinets and bottles, etc. to be put -Leaves no residue -Flammable concentrations Alcohol into Biological Safety Cabinets -Effective bactericide with -No residual activity and limited effective exposure time above 90%) -Use as topical antiseptic on intact adequate contact time due to high rate of evaporation skin -Non-staining -Some incompatibility with rubber and plastic material -Contact Time from 10-30 minutes Phenolics 500 ppm active Triclosan, -Commonly used to clean walls, -Good effectiveness in organic -Toxicity varies with specific compound, agent or 1%-5% chloroxylenol floors, etc material -Can be absorbed through skin and Latex gloves -Useful in areas where organic -Effective with detergent -Some formulations may have unpleasant odor matter cannot always be removed, -Has some residual -Corrosive such as animal areas effectiveness -Skin irritant -Contact Time approximately 10 -Stable in storage -Not effective against spores and some viruses minutes -Prolonged contact deteriorates rubber Quaternary 400 ppm active Vindicator, -Surfaces must be rinsed free of -Strong surface activity -Easily inactivated by organic materials, anionic Ammonium agent or 0.1%- Lysol I.C., Hil- anionic soap or detergents before -Low toxicity detergents, and salts of metals in water (hard water) Cmpds. 2.0% Phene use -Non-corrosive -Skin irritant -Commonly used to clean walls, -Effective over wide pH range -Ineffective against Gram-negative, tubercle bacillim floors, etc -Easily prepared and used spores, and viruses -Contact Time approximately 10 -Effective against Gram-positive -Neutralized by soap minutes microbes -Contact dermatitis can result Iodophor 25-1600 ppm FAM 30 -Effective against Gram-negative -Stable if kept cool & tightly -Poor activity against spores available iodine and Gram-positive organisms, some covered -vaporizes at 120oF (should not be used in hot water) viruses, and tubercle bacilli -built in indicator (active if brown -may tarnish silver, silver plate, copper -Most effective in acidic solution or yellow) -Relatively expensive -Refer to manufacturer for required -generally non-corrosive -Can Be Toxic contact time -readily miscible with water -Dilution critical -Convenient