CONSIDERATIONS IN SELECTION OF ANTISEPTICS AND DISINFECTANTS FOR VETERINARY DISPENSARIES Introduction Antiseptics are used in surgery for antisepsis of the surgical site, surgeonƎs hands disinfect surgical instruments, apparel, and hospital premises. Other common uses are as disinfectants for home and farm premises, food processing facilities, in water treatment, in public health sanitation As antiseptics in soaps, teat dips, dairy sanitizers, The same compound --ASAS or DIS, dep.on conc., conditions of exposure, number of organisms, etc. Maximal efficiencyefficiency--properproper concentration of the agents for the purpose intended Selecting antiseptics/disinfectants
Three factors are to be considered the type of microorganism the agent has to eliminate(bacteria, virus, fungi or vegetative or spore forms) the environment in which the agent will be used (living tissue/inanimate, presence or absence of dirt/debris) the characteristics of agent(corrosiveness, cost and antimicrobial spectrum) Classification Physical agents Moist HeatHeat-- ƋƋBBoiling water & autoclaving Pasteurization Dry heatheat-- ƋƋFFlaming,, Incineration,, Baking in oven Filtration Radiation --IonizingIonizing ƋƋXX--raysrays and gamma rays; NonNon--ionizingionizing ƋƋUVUV and infrared light Ultrasonic Vibrations Chemical Agents 1.1. Acids and alkalies boric acid, benzoic acid, NaOH Na2CO3 quick lime(CaO) 2. Halogens--iodineiodine Iodophores Chlorine, bromine 3. Alcohols--ethylethyl alcohol(70%), isopropyl alcohol (50%), benzyl alcohol 4. Phenols and Phenolics phenol, cresol, lysol, hexyl resorcinol, hexachlorophene, chloroxylenol 5. Heavy Metals and their compounds mercuric chloride, merchurochrome, AgNO3, ZnO, CuSO4 6. Oxidizing agents H2O2, KMnO4, Zn permanganate, sodium perborate, benzyl peroxide 7. Reducing agents/ Alkylating agentsagents-- fformaldehyde, ethylene oxide(gas), glutaraldehyde 8.8. Dyes acriflavine, euflavine, proflavine, gentian violet, crystal violet, methylene blue, brilliant green, fluorescein dye, aminocrine 9. Detergents/surfactants/ Wetting agents/Cleansers cationic(Quaternary ammonium compoumndscompoumnds-- benzalkonium chloride, benzethonium chloride, cetrimide, acertyl pyridinium chloride) anionic (soaps) nonionic ( amphoteric) 10. Miscellaneous /Biguanides--chlorhexidinechlorhexidine HCl Alcohols
Ethyl alcohol (70% ethanol) isopropyl alcohol (50% isopropanol) Isopropanol is slightly more potent than ethanol As a skin disinfectant and rubefacient. AlcoholAlcohol--basedbased hand rinses have rapid--actingrapid acting antiseptic effects Wide germicidal activity,non corrosive, butbut--firefire hazardous risk Limited residual activity due to evaporation Limited activity in the presence of organic matter and not effective against bacterial or fungal spores Acids and Alkalies Strong mineral acids (HCl, H2SO4, etc) in concentrations of 0.10.1--11 N Corrosive action limits their usefulness Acids as food preservativespreservatives--,, benzoic acid, antiseptics (eg, boric acid, acetic acid), fungicides (eg, salicyclic acid, benzoic acid)) Acetic acid, 1%, used in surgical dressings, and 0.25% acetic acid is a useful antibacterial agent for irrigation of the urinary tract. At 5%, it is bactericidal to many bacteria and has been used to treat otitis externa produced by Pseudomonas , Candida, Malassezia , or Aspergillus spp. Acids and Alkaliesƅcontd Hydroxides of sodium and calcium used as disinfectants their caustic property usually limits their application on tissues. A 2% solution of soda lye (contains 94% sodium hydroxide in hot water) used is a potent caustic Calcium oxide , ie, lime (hydrated or airair-- slaked lime), soaked in water produces Ca(OH)2. are used to disinfect premises Chlorhexidine
potent activity against gramgram--positive,positive, some gram--negativegram negative bacteria but not against spores activity is enhanced by alcohols, quaternary ammonium compounds, and alkaline pH, depressed by high concentrations of organic matter (pus, blood, etc), hard water, and contact with cork.. incompatible with anionic compounds, including soap 4% emulsion of chlorhexidine gluconate is used as a skin cleanser, 0.5% (w/v) solution in 70% isopropanol as a general antiseptic 0.5% solution in 70% isopropanol with emollients as a hand rinse. ChlorhexidineChlorhexidine--alcoholalcohol mixtures are particularly effectiveeffective in that they combine the antiseptic rapidity of alcohol with the persistence of chlorhexidine. low potential for systemic/ dermal toxicity ----shashampoos,mpoos, ointments, skin and wound cleansers, teat dips etc Hydrogen peroxide: (3%) Effervescent action (liberates oxygen when in contact with catalase present on wound surfaces) helps to remove pus and cellular debris from wounds cleaning and deodorizing infected tissue. action is of short duration and is limited to the superficial layer of the applied surface, no penetration of the tissue. Benzoyl peroxide cause skin irritation keratolytic and antiseborrheic activity treating pyoderma in dogs Potassium permanganate is an effective algicide (0.01%) and virucide (1%) for disinfection concentrations >1:10,000 tend to irritate tissues. Staining of tissues is disadvantage. Chocolate brown coloured old solutions indicate the loss of activity Iodine Elemental iodine is a potent germicide with a wide spectrum of activity and low toxicity to tissues. Poorly soluble in water but readily dissolves in ethanol, which enhances its antibacterial activity Tincture iodine (strong/weak)) Wide germicidal activity including fungi and bacterial spores, characteristic odor corrosive and has limited activity in the presence off organic matter Iodophores povidonepovidone--iodineiodine slowly release iodine as an antimicrobial agent do not sting ,stain. nontoxic to tissues but may be corrosive to metals. Effective against bacteria, viruses, and fungi but less so against spores. Good antibacterial activity even in the presence of organic matter Change color when the activity is lost. Phosphoric acid is often mixed with iodophores to maintain an acidic medium. Used in teat dips, dairy sanitizers and for various dermal and mucosal infections Chlorine potent germicidal effect against most bacteria, viruses, protozoa, and fungi ( 0.1 ppm) Much higher conc. in presence of organic matter. strong acid smell, is irritant to the skin and mucous membranes. Used to disinfect water supplies ,inanimate objects (eg, utensils, bottles, pipelines) in dairies. Inorganic chlorides include sodium hypochlorite (Dakin's solution) solutions (bleach)and calcium hypochlorite. Chlorinated lime (bleaching powder): mixture of calcium hypochlorite and calcium chloride; for disinfection of water, livestock premises, destruction and disposal of carcasses ,elimination of pathogens from organic matter Phenol (carbolic acid) bacteriostatic at 0.10.1--1%;s1%;s bactericidal/fungicidal at 11--2%.2%. T Activity enhanced by warm temperatures Decreased by alkaline medium, lipids, soaps, and cold temperatures. 5% solution --stronglystrongly irritating, corrosive to tissues. Oral ingestion/ excess application to skin can cause systemic toxicity. Cresol :: 2% solution of either pure or saponated cresol (Lysol) in hot water is a disinfectant for inanimate objects Formaldehyde 11--10%10% solution used as a disinfectant Glutaraldehyde 11--2%2% alkaline solution (pH 7.5--8.5)7.5 8.5) in 70% isopropanol is a more potent germicide than 4% formaldehyde. used to sterilize surgical and endoscopic instruments and plastic and rubber apparatus Teat dips Soaps Anionic detergents which emulsify lipoidal secretions of the skin Remove, along with most of the accompanying dirt, desquamated epithelium and bacteria, which are then rinsed away with the lather. The antibacterial potency: enhanced by inclusion of certain antiseptics, eg, hexachlorophene, phenols, carbanilides, or potassium iodide. They are incompatible with cationic surfactants Cationic detergents Quaternary ammonium compounds (eg, benzalkonium chloride, benzathonium chloride, cetylpyridinium chloride, cetyl pyridinium bromide/cetrimide) Activity is reduced by porous or fibrous materials (eg, fabrics, cellulose sponges) that adsorb them Inactivated by anionic substances (eg, soaps, proteins, fatty acids, phosphates). Limited value in presence of blood and tissue debris. Effective against most bacteria, some fungi , protozoa but not against viruses and spores. Aqueous solutions of 1:1,000 to 1:5,000 have good antimicrobial activity, especially at slightly alkaline pH. When applied to skin, they may form a film under which microorganisms can survive, which limits their reliability as antiseptics. Concentrations >1% are injurious to mucous membranes Chloroxylenols Parachlorometaxylenol ,dichlorometaxylenol broadbroad--spectrumspectrum with more activity against gramgram--positivepositive than gram--negativegram negative bacteria. Active in alkaline pH; however, contact with organic matter diminishes their activity. 5% chloroxylenol solution (in ĮĮ--terpineol,terpineol, soap, alcohol, and water) is diluted with water (1:4) for skin sterilization 1:25 to 1:50 for wound cleansing and irrigation of the uterus and vagina Preferred antiseptics
with antifungal activity phenols, chlorhexidine , iodine, povidoneiodine,hypochlorite,cetrimide with antviral activity isopropanol,ethanol,formaldehyde glutaraldehyde,sodium hyopochlorite,phenol, potassiumpermanganate,hydrogen peroxide, iodophors Recommended antiseptics/disinfectants for hospital situations All the instruments have to be immersed for 30 mins and rinsed and autoclaved. 2% sodium hypochlorite: for gloves, syrienges, needles , blood spills on floor, floor washing. lab glasswares 2% benzalkonium chloride: foreceps, thermometer 2% glutaraldehyde: InstrumentsInstruments--catheters,catheters, laryngoscope, endotracheal tubes 6% hydrogen peroxide: removal of blood clots from tubes,catheters, dressing wounds Benzalkonium chloride: hand wash, foreceps, catheters , instruments Phenol: disinfecting toilets Povidone iodine: surgical scrub, painting skin, dressing, hand wash Ethyl alcohol: antiseptic at injection site, furniture disinfection