HERD HEALTH PIH80 PURDUE UNIVERSITY. COOPERATIVE EXTENSION SERVICE. WEST LAFAYETTE, INDIANA Selection and Use of Disinfectants in Disease Prevention Authors H. Neil Becker, Melrose, Florida George W. Meyerholz, USDA, Washington, D.C. Jack M. Gaskin, University of Florida Reviewers Glenn and Miranda Elliott, Galivants Ferry, South Carolina Miksch, University of Kentucky John Thomson, South Dakota State University Kurt Wohlgemuth, North Dakota State University Cleaning and disinfecting are very important in controlling the accumulation and spread of disease-causing microorganisms. It also improves air quality and reduces dust. This is especially true in modern swine buildings where continuous use and high con- centrations of animals may result in a condition referred to as ``disease buildup.'' The all-in, all-out management program is recommended to facilitate the cleaning process and to improve pig performance. As disease-producing bacteria, viruses, fungi, and parasite eggs accumulate in the environment, disease problems can be transmitted to each successive group of animals raised. Thorough cleaning and disinfecting often provides the only successful solution to breaking the disease cycle and controlling the prob- lem. Disinfection can be improved when the area is thoroughly cleaned. Organic matter such as dirt and manure can protect microorganisms and inactivate certain disinfectants. Manure remo- val followed by a simple scrubbing , a high velocity stream of water, or a steam generator can do an excellent cleaning job. Detergent solutions hasten dirt and manure removal by increasing the wetting speed and breaking organic matter into small particles that easily wash away. A siphoning system or propor- tioner can be utilized to combine a detergent or a detergent- disinfectant with the cleaning process. A high pressure stream of water or spray (200-1000 psi) can be used to remove manure and debris. Portable steam generators, ``steam jennies,'' are also used for cleaning dirty surfaces. The nozzle should be held not more than 6-8 in. from the surface to have much value in killing organisms. The steam cleaning-detergent process works effectively on wood, metal, concrete and especially on slotted and wire floors. Many disinfectants and detergents work better at warm temperatures of the steam generator. Effective cleaning removes more than 95% of the contamination and permits disinfectants to more easily penetrate and kill organisms. Choosing a Disinfectant Many factors must be weighed before choosing a proper disin- fectant for a particular job. A germicide intended for the disin- fection of a building should work well in the presence of organic matter, be compatible with soaps or detergents, be harmless to building materials, and be relatively non-toxic. A disinfectant suitable for decontaminating a building might be too toxic for use in sanitizing feed and water utensils. Select the disinfec- tant to fit the job. Chemical agents have different mechanisms of action and spectra of activity. Warmer temperatures with some disinfectants, such as those containing chlorine or iodine, drive off the active ingredient from the solution. Some disinfectants are influenced by an acid or alkaline pH and/or hardness of the water. Charac- teristics and uses of common disinfectants can be evaluated using Table 1. Commonly Available Disinfectants Saponated solution of cresol is almost insoluble, especially in hard water. Compounds of cresol with soap (saponated) such as LysolO are normally used to increase solubility and are applied in a 2-4% solution; a dilution of 4 oz. of cresol per gal. of water is recommended. Hot solutions are more effective. Saponated solution of cresol is an effective disinfectant to use in the presence of organic matter and is suitable for disinfecting animal quarters, vehicles and premises. These compounds can also penetrate wooden materials. Cresol has a strong and persistent odor to consider when using in farrowing houses or other tightly enclosed buildings. Synthetic phenols such as orthophenol are available. They have a wide range of antimicrobial activity and are relatively good in the presence of organic material. They usually have no objectionable odor. Some are fortified with synthetic detergents for one-step cleaning and disinfecting. They are sold under various trade names (see Table 1). Free Iodines: Tincture of iodine (2% iodine in alcohol) and strong tincture of iodine (7%) have been used as antiseptics and disinfectants; but because of their staining, corrosive and skin irritant properties, organic or ``tamed'' iodophor compounds are commonly used. Tincture of iodine could be used on skin prior to, or after, minor surgical procedures such as castration. As with alcohols, the proper concentration must be maintained. Iodophors are combinations of iodine and agents that aid solubility, usually non-ionic detergents. They are non-staining, non-irritating, and largely free from the risk of producing skin hypersensitivity reactions. Iodophors, sometimes referred to as ``tamed iodines'' or ``organic iodines'' are now commonly used for disinfection of utensils, equipment and precleaned surfaces. They are not highly active in the presence of organic material. In combination with detergents, they provide a slow release ger- micidal action that has residual activity for at least 7 days after application. They are effective in hard water but should not be used with alkali soaps. Alcohols: In general, ethanol (grain), methanol (wood) and isopropyl (rubbing) alcohols are not suitable for most disinfec- tion applications found in pork production. Isopropyl alcohol could be used to maintain sterility of clean instruments but other products are usually better suited. After a ``surgical scrub,'' it could also be used as a final application to skin prior to surgical procedures. If used, proper concentrations must be maintained (70-78%). Chlorine compounds have rapid action against bacteria, spores, fungi, and viruses. Preliminary cleaning is essential before disinfection with chlorine compounds because their activity is substantially reduced by the presence of organic matter. Solutions of sodium hypochlorite, similar to those used as laundry bleaches, are commonly used to disinfect utensils. Such solutions decompose upon exposure to light and should be kept protected. A 2% solution of calcium hypochlorite (bleaching powder, chloride of lime) is an economical and effective disin- fectant for buildings and utensils. Its action, however, is readily dissipated by organic matter and careful cleaning should precede its use. Powdered chlorinated lime may be dusted directly on contaminated livestock quarters as a deodorant as well as a disinfectant. It should be stored in airtight containers because it deteriorates when exposed to air. Chloramines are organic chlorine compounds which release chlorine slowly and exert a pro- longed bactericidal effect. They are less toxic and irritating than the hypochlorites. Lye (soda lye) contains approximately 94% sodium hydroxide, a very effective disinfectant. Concentrated lye is a caustic poison and must be handled with great care. Solutions of lye will damage painted or varnished surfaces and textiles if allowed to remain in contact with them for very long. Lye does not injure bare wood, enamelware, earthenware or any of the common metals except aluminum. It is not highly effective against tuberculosis organisms and spore-forming bacteria as commonly used. For highly effective disinfectant purposes, lye should be applied as a 5% solution (one 131/2 oz. can to 2 gal. of water). It is com- monly used at a lower concentration (1-2 lb. to 10 gal. of water) that is less hazardous to the user. Chlorhexidine is a synthetic compound with action against a variety of bacteria and many viruses. It is not appreciably inac- tivated by small quantities of organic matter and is non-toxic. Chlorhexidine is relatively ineffective against the gram-positive cocci, Pseudomonas, and resistant viruses such as the parvo- viruses. Quaternary ammonium compounds are surfactants commonly used for general disinfection of dairy, meat-packing, and food- handling equipment. They are antibacterial but do not possess substantial viricidal, fungicidal or sporicidal action and are used chiefly as sanitizing rinses after mechanical cleaning. These compounds are not suitable for disinfection of premises since they are readily inactivated by organic matter. They are neutralized by soaps so surfaces to be disinfected with them should be pre-rinsed. Formaldehyde and other aldehydes can be purchased as an aqueous solution containing about 40% formaldehyde gas, commonly known by the name ``formalin.'' A concentration of 4% formal- dehyde gas is a reliable disinfectant that is lethal to anthrax spores within 15 min. Fumigation with formaldehyde has been popu- lar for use in large poultry houses and swine units. Proper disinfection depends on a long period of exposure at proper con- centration and humidity. Because the gas tends to condense at low temperatures, fumigation with formaldehyde is unreliable below 65o F. Temperatures above 80o F are preferred. Buildings should be thoroughly cleaned before fumigation and must be aired for 12-24 hr. before reuse. There are two methods of fumigating with for- maldehyde gas. The first employs wide bottom buckets placed approximately every 10 ft. through the length of the building. In each receptacle place 175 gm. (10 level tablespoons) of potassium permanganate, then 12 oz. (11/2 cups) of a 40% solution of for- maldehyde (formalin) are poured over it. Under proper conditions this mixture will generate enough formaldehyde gas to disinfect 1,000 cu. ft. of space. Paraformaldehyde is a white powder used in commercially available electric heating units which release the gas from the powder. With either method, the floor should be moistened about 15 min. before fumigation; and the building must be kept tightly closed for at least 8 hr. Glutaraldehyde is a more effective germicide than formaldehyde and has a less irri- tating odor. However, it is significantly more expensive. A com- mercial spray fumigant is also available. The formula slowly releases formaldehyde and kills bacteria on contact and for up to 7 days. Use of fumigants is hazardous to humans and animals; use properly. Footbath Preparation and Maintenance Footbaths can be effective in preventing contamination through traffic between buildings (by footwear). They also serve as a constant reminder of the need for hygienic measures. If footbaths are not properly prepared and maintained, they are not only ineffective but act as sources of further contamination while providing a sense of false security. The following should be considered in preparing and maintaining footbaths: o The footbath should be long and wide enough so people are forced to walk through it. o The design should facilitate easy drainage and cleaning. o The depth should be at least 4 in. o It should be protected from weather (flooding, freezing). o Disinfectant should be replaced when dirty (daily, if needed). o Phenols and cresols are most commonly used but iodophors are also sold for footbaths. o Clean footwear is more effectively disinfected than dirty, mud, or manure covered footwear. Provide adequate facilities (water spray) to easily and thoroughly pre-clean footwear. Safety Precautions Many cleaners and most disinfectants are poisonous. Store in tightly closed containers in a safe, locked area out of reach of children and other unauthorized persons, and away from feed and other supplies. Do not use bleach and ammonia together. Keep the labels on all containers. Read and follow directions carefully. Observe all safety precautions. Avoid skin contact, wear goggles and avoid breathing of spray mist or fumigant. Practical Testing for the Effectiveness of Disinfection Pro- cedures Laboratory testing for the effectiveness of disinfectants or disinfection procedures may be complicated and can be misleading if cleaning and disinfection is not done thoroughly. However, veterinarians can provide a practical and simple method (inexpen- sive) for interested pork producers. Swab samples are obtained from surfaces before and after disinfection and cultured for various bacterial organisms. A marked difference in the type and quantity of bacteria grown in cultures should be seen between the samples. References Disinfection in Veterinary and Farm Animal Practice. 1987. Ed. by Linton, A.H., Hugo, W.B. and Russell, A.D., YearBook Medi- cal Pub., 35 E. Wacker Dr., Chicago, IL 60601 Veterinary Pharmacology and Therapeutics. 1988. 6th ed. Ed. by Booth, N.H. and McDonald, L.E. Chapter on Antiseptics and Disinfectants by Huber, W.G., Iowa State Press, Ames, IA. __________________________________________________________________ |Reference to products in this publication is not intended to be | |an endorsement to the exclusion of others which may be similar. | |Persons using such products assume responsibility for their use | |__________________________________________________________________| REV 6/90 (5M) Table 1. Common disinfectants-characteristics and uses. ______________________________________________________________________________ | Formaldehyde Chlorine | | and other hypochlorites| | Chlorhexidine aldehydes chloramines | |_____________________________________________________________________________| |Spectrum of activity | | Gram pos. bacteria S.A.,1 not Yes Yes | | pyogenic cocci | | Gram neg. bacteria S.A., not Yes Yes | | pseudomonads | | Tuberculosis bacilli S.A. Yes S.A. | | Bacterial spores S.A. at 1% Yes S.A. | | concentration | | Fungi S.A. Yes Yes | | Viruses S.A., not Yes S.A. | | parvovirus | |_____________________________________________________________________________| |Special properties | | Resistance to organic debrisGood Good Very poor | | Effect of hard water None None None2 | | Detrimental effect of heat No 4 5 | | Residual activity Yes 6 7 | | Most effective pH range Alkaline Not affected by pHAcid | | Compatibility with anionic Yes Yes Yes | | surfactants (soaps) | | Compatibility with non- Yes Yes Yes | | ionic surfactants | |_____________________________________________________________________________| |Disadvantages Reduced activityIrritating fumes,8Inactivation | | against certain by organic | | organisms debris | | | |_____________________________________________________________________________| |Commonly used concentrations | | Disinfecting solution 1% 2-8% Hypochlorites| | 3-5% 10,11 | | Sanitizing solutions 0.5% 1-2% Hypochlorites| | 2-3%11 | |_____________________________________________________________________________| |Appropriate uses | | E - Equipment | | Ce - Clean equipment E,P,F E,P,F CE | | P - Premises | | F - Footbaths | |_____________________________________________________________________________| |Common brands and NolvasanO CidexO Chloramine-TO| | names12 DC & RO ChloroxO | | FormaldegenO HalazoneO | | Formalin | | | | | | | | | | | |_____________________________________________________________________________| Table 1. (Continue..) _____________________________________________________________________________ | Quaternary | | Sodium ammonium Cresols | | Iodophors hydroxide compounds phenols | |____________________________________________________________________________| |Spectrum of activity | | Gram pos. bacteria Yes Yes Yes Yes | | | | Gram neg. bacteria Yes Yes S.A. Yes | | | | Tuberculosis bacilli S.A. S.A. No S.A. | | Bacterial spores S.A. Yes (5-10%No No | | solution) | | Fungi Yes Yes S.A. S.A. | | Viruses S.A. Yes S.A. S.A. | | | |____________________________________________________________________________| |Special properties | | Resistance to organic debri Poor to fairGood Fair Excellent | | Effect of hard water None2 None 3 | | Detrimental effect of heat 5 No No No | | Residual activity Yes Yes No Yes | | Most effective pH range Acid Alkaline Alkaline Acid | | Compatibility with anionic Yes Yes No Yes | | surfactants (soaps) | | Compatibility with non- Yes Yes Yes No | | ionic surfactants | |____________________________________________________________________________| |Disadvantages InactivationCaustic Incompatible9 | | by organic w/soaps | | debris - limited | | spectrum | |____________________________________________________________________________| |Commonly used concentrations | | Disinfecting solution 50-75 ppm 2-10% 400-800 ppm Variable | | | | Sanitizing solutions 12-25 ppm 200 ppm | | | |____________________________________________________________________________| |Appropriate uses | | E - Equipment | | Ce - Clean equipment CE P CE E,P,F | | P - Premises | | F - Footbaths | |____________________________________________________________________________| |Common brands and BetadineO Lye GermexO Cresl-400O | | names12 IofecO Hi-LetholO EnvironO | | IsodyneO San-O-FecO Tek-TrolO | | LosanO WardenO LysolO | | Tamed ZephiranO Orthophen- | | IodineO ylphenol | | WeladolO Sodium | | orthophenyl| | phenate | |____________________________________________________________________________| 1. S.A. - Some Activity. 2. Unless hard water is alkaline. 3. Reduces speed of kill. 4. Formaldehyde gas works best at 80-140\(deF. 5. Use at less than 110\(deF, active principal driven off by heat. 6. No, except slow-release formulas. 7. Hypochlorites: No, chloramines: Yes. 8. Glutaraldehyde is less irritating and is superior to formaldehyde as a germicide. 9. Strong odor with coal and wood tar distillates. 10. 3.3% Chlorox inactivates parvovirus on clean surfaces. Chloramines variable. 12. Products listed are intended as examples, not endorsement; many suitable products are not listed. Table 2. Definitions. _____________________________________________________________________ |Anti- a prefix meaning against; to prevent. | |Antiseptic an antimicrobial agent sufficiently free of toxic| | effects that may be used on body surfaces, e.g. | | alcohol, iodine. | |Antisepsis the prevention of infection(s) or the result of | | infection(s). | |Caustic corrosive or destructive to living tissues | |-cidal suffix meaning "to kill". | |Detergent an agent that aids in cleansing; may be used in a| | solution with disinfectants. | |Disease the result of any condition that allows or | |buildup permits the number of disease producing organisms| | to increase. | |Disinfectant an antimicrobial agent that is too toxic, | | irritating or corrosive to be used on body | | surfaces but is suitable for use on equipment, | | floors or environmental areas. | |Fumigation exposure of an area or object to disinfecting | | fumes. | |Germicide an agent (substance) that kills germs. | |Germicidal the relative ability of an agent (substance) to | |activity kill germs. | |Germ(s) disease producing microorganisms. | |Hardness amount of calcium, magnesium, or other minerals | |of water dissolved in water that may interfere with | | cleansing ability. | |Hypersensitivity an exaggerated reaction of the body or tissues to| |reaction contact with a substance or foreign agent; | | allergic reaction. | |Micro- a prefix meaning small; not seen with the naked, | | unaided eye. | |Microorganism small, living organisms usually seen only with | | the use of a microscope. | |Organic Matter material that comes from living organisms or | | tissue, e.g., blood, manure, dirt, urine, | | afterbirth, mucus. | |pH the symbol used to express whether a solution is | | acidic or basic (alkaline). pH 7 is neutral, | | below 7 is acid, and above 7 is alkaline. | |Proportioner a device that meters (adds) one substance | | (solution) to another; as a liquid proportioner. | |Sepsis the presence of disease producing organisms | | (germs) or their toxins in blood or other | | tissues; putrefaction; decay. | |-static suffix meaning "to stop". | |___________________________________________________________________| ______________________________________________ Cooperative Extension Work in Agriculture and Home Economics, State of Indiana, Purdue University and U.S. Department of Agri- culture Cooperating. H.A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the Acts of May 8 and June 30, 1914. It is the policy of the Cooperative Extension Service of Purdue University that all persons shall have equal opportunity and access to our programs and facilities. .