GUIDELINE for Disinfectant choice in feline veterinary hospitals, shelters and cat households

Published: 14/08/2015
Last updated:
Last reviewed:

The Disinfection guidelines were first published in the Journal of Feline Medicine and Surgery (2015) 17, 594-605; the present update has been authorised by Diane Addie and edited by Karin Möstl.

Synopsis

Regardless of whether a pathogen is viral, bacterial, parasitic or fungal, or an emerging unknown, the mainstay of infectious disease prevention is hygiene, and the cornerstone of good hygiene is effective disinfection. Deficiency of the enzyme UDP-glucuronosyltransferase renders the cat susceptible to toxic effects of phenol based disinfectants (including essential oils tea tree and clove), so these are best avoided in feline environments.

Certain pathogens present a challenge to kill effectively: parvovirus, protozoal oocysts, mycobacteria, bacterial spores and prions resist most disinfectants but can be eliminated through heat, especially steam, which is the only thing which will kill protozoal oocysts.

Heat is the safest, and most effective, disinfectant, but cannot be universally applied, for example, to living skin. Temperatures in washing machines and dishwashers should be at least 60℃ to eliminate pathogenic spores and resistant viruses.

Enveloped viruses are susceptible to most disinfectants, and of the non-enveloped viruses parvovirus is universally recognized to be the model most difficult to eradicate. Sodium hypochlorite is recommended for many applications: cleaning of floors, food preparation surfaces and utensils, laundry. Quaternary ammonium compounds (e.g Benzalkonium chloride) are probably best avoided. Skin scrubs and rubs containing alcohols are more effective than those containing chlorhexidine and less subject to contamination. The future of veterinary disinfection may include ultraviolet radiation and more use of silver compounds.

Introduction

Infectious disease is a major challenge for the domestic cat (Felis catus). In nature, a solitary creature, the cat has been forced, by domestication, to sometimes live in un-naturally highly dense populations (for example, shelters or breeding households) which results in exposure to un-naturally large doses of pathogens at a time when stress may already be compromising the cat’s immune system and ability to deal with it.

Hygienic routines and disinfection are the method of choice for eliminating methicillin resistant staphylococcus aureus (MRSA) or virulent systemic feline calicivirus (VS-FCV) from premises, and is especially important in situations where there is an emerging, or unknown, contagion, when neither vaccination, nor specific testing, can prevent transmission. There are three priorities when choosing disinfectants for use around the cat: the first, obviously, is efficacy. The second, perhaps less obvious, is avoidance of toxicity to the cat: the cat’s unique metabolism renders him especially sensitive to many things which are perfectly safe for other species, for example, phenol based disinfectants. Outwith the scope of this article, but also very important, is consideration of the effects of various disinfectant exposures on humans, especially in veterinary hospitals and shelters, where exposure is likely to be a daily occurrence and long term. Cleaning chemicals have been associated with airway irritation, asthma, contact dermatitis in humans and animals, and even, with prolonged exposure, neoplasia. The strongest airway irritants in cleaning products are bleach (sodium hypochlorite) which releases chlorine gas, hydrochloric acid, and alkaline agents (ammonia and sodium hydroxide), which are commonly mixed together (Quirce). Cleaning agents are divided into sensitisers (amine compounds; quaternary ammonium compounds, disinfectants, scents containing terpenes, isothiazolinones, formaldehyde) and irritants (chlorine, ammonia, hydrochloric acid, monochloramine, sodium hydroxide, quaternary ammonium compounds). (Quirce)

Different pathogens require different approaches to effective disinfection, so that recommendation of a single disinfectant for all purposes is not possible. In addition, there is no single solution for all applications: for example, steam cleaning, which is necessary to eliminate protozoal oocysts from a premises, (Ernst) is not feasibly applied to the hands of the veterinary surgeon or the skin of a cat. Thus there is no one single solution to the question of disinfection in veterinary practice. Another question outwith the scope of this review is that of human psychology: hand hygiene is the most important tool in nosocomial infection control ever since Semmelweis observed its immense effect on the incidence of childbed fever (Kampf & Kramer) in 1847, yet obtaining compliance remains a challenge over a hundred years on. (Fuller; Umit) However, apparently people are more willing to use a hand rub than to wash their hands in water. (Kampf & Kramer)

In each class of pathogen certain things have been identified as the most difficult to kill – e.g. of the viruses, parvovirus is the most resistant – so that if a disinfectant kills parvovirus, it is likely to kill most other viruses as well. We are fortunate, as feline microbiologists, in that there are many publications available on disinfecting feline calicivirus (FCV) as it is often used as a surrogate for human norovirus, (Steinmann) which is difficult to grow in cell culture, even though FCV, as a respiratory calicivirus, differs in many essential properties from the human enteric calicivirus. Details of any special disinfection requirement for each particular pathogen are given in their respective ABCD guidelines, while only anything of note is reported in this paper.

Some organisms will die outside the host without any intervention (e.g. feline leukaemia virus, feline herpesvirus): survival times outside the host were presented elsewhere (Mostl et al, 2013; Addie 2008).

This review is intended for the general veterinary practitioner and specialised areas, such as the disinfection of blood for transfusion, bone marrow/organs for transplant, and sensitive specialized equipment, for example endoscopes, will not be covered. For a review of endoscope disinfection, see Greene et al, 2012.

Disinfection – Definition and principles

Disinfection is a potent means to reduce the number of pathogens on a surface. It minimizes the risk of infection for animals and humans that come into contact with that surface.

Disinfection does not result result in sterility, this can be achieved by other methods, and only for very confined surfaces, i.e. on instruments, or liquids, such as infusion solutions.

Disinfection is always non-specific. It does not inactivates specifically pathogens. It will kill most of the bacteria on a surface, including the pathogenic ones. It is therefore important, that a disinfectant is capable of substantially reducing the bacterial burden on a surface. This is defined in most test protocols as a reduction of the number of infectivity by at least 4 log10.

Disinfection can be achieved by various methods, The bacteria, viruses and other pathogens can be damaged and inactivated by physical treatment, which is basically heat and radiation and also by chemical substances. The latter is the most common way of disinfection and can be applied to virtually all surfaces.

Physical disinfection

Heat and steam

Heat is by far the most broad spectrum method of disinfection: moist heat is more effective than dry heat, especially under pressure. When used correctly, steam under pressure (i.e. autoclaves) is the most efficient means of achieving sterility (Greene et al). Steam cleaners are widely available which can be used on soft furnishings (e.g. carpet), as well as floors and work surfaces.

In veterinary hospitals, shelters and the home, heat can be used in dishwashers, washing machines and incinerators to inactivate infective agents. Introduction of a dishwasher (amongst other measures) ended an outbreak of MRSA in a human neonatal hospital (Agca et al, 2014). Household dishwashers modified to achieve a temperature of 71oC were even proposed as a substitute for autoclaving in smaller surgeries (Ebner et al, 2000). However, care must be taken that the dishwasher itself does not become a source of cross-contamination (Ståhl Wernersson et al, 2004). Sterilisation efficacy is dependent on time of exposure of the pathogen to heat, and on whether or not a chemical disinfectant is also used.

Human safety has also to be considered: zoonotic infections may be indirectly transmitted to laundry workers: although from a human source (i.e. not zoonotic), salmonella was transmitted to laundry workers (Standaert). One heavily contaminated item can contaminate an entire laundry load, viruses can be transferred from contaminated laundry to uncontaminated laundry during washing (Gerba; Honisch); Cryptosporidium oocysts can attach to fabrics during machine washing (O’Toole et al). In a human hospital, a nosocomial outbreak of Microsporum canis infection was linked to laundry contamination (Shah 1988). The temperature needed for decontamination depended on washing time and detergent type. (Honisch) For mycotic contamination, Ossowski and Duchmann (1997) found that reliable decontamination was achieved by laundering at 60oC, regardless of the textiles and detergents used: Nims reports that 60oC (or higher) is also the optimal temperature for inactivating FCV. Temperatures of 56oC and over will kill 99% of giardia cysts. (Mtapuri-Zinyowera) Addition of sodium hypochlorite with detergent significantly reduced the numbers of viruses in laundry (Gerba) and the addition of activated oxygen bleach increased effectivity against a number of bacteria (Honisch).

Microbial size is an important determinant in the fabric attachment-detachment process during the machine washing cycle, with larger microorganisms showing greater transference to, and retention on, fabric swatches than smaller ones. Transfer efficiencies are greater for cotton toweling than for other fabric types both before and after the washing machine spin cycle, indicating that it is not only the properties of the microorganism that influence transfer efficiency but also the properties of the fabric. (O’Toole et al).

Parvovirus can resist temperatures of 80℃ for at least an hour. (Mahnel, 1977)

Ultraviolet-C

Ultraviolet light radiation in the C range (UV-C; typically 254 nm) and the B range (UV-B; 280–320 nm) has been investigated as a method of disinfecting water, food preparation surfaces, (Nims) and hospital rooms. UV-C-emitting devices can decrease the bioburden of important pathogens (Clostridium difficile and vancomycin-resistant enterococci but not significantly Acinetobacter) in real-world settings such as hospital rooms. (Anderson et al).

UV radiation only works on surfaces. It is therefore important that UV radiation is only appled an clean surfaces. UV lamps lose the ability to produce UV light. Most of the commonly used bulbs need to be replaced after around 10.000 hours of use.

The efficacy of UV radiation depends on the intensity of the radiation. For viruses the intensity necessary to reduce infectivity by 4 logs differs between the various viruses, but is in the range of 1000 to 10.000 mJ/cm2.

Parvoviruses and circoviruses appear to be more susceptible to UV-C inactivation than are the caliciviruses (Nims).

Chemical Disinfection

Both pure active substances and commercial products can be used for efficient disinfection, provided it is adjusted to an effective microbiocidal concentration.

It is therefore advisable to exclusively use commercial products. They usually contain a mixture of various active subtances and the side effects are minimized. Above all, however, they are efficacy tested and the microbiocidal concentration was determined by an independent institution.

Efficacy testing, licensing of biocides

In Europe chemical disinfectants are considered as biocides and as such the need to be licensed according to REGULATION (EU) No 528/2012 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 22 May 2012 concerning the making available on the market and use of biocidal products .All disinfectants will to a varying degree affect the environment and will react with inert materials, such as the various surfaces to be disinfected. The licensing procedure includes therefore tests for the ecotoxicologic effect of the biocide, as well as the potential to harm animals and men and to be compatible with various materials. Another important part of the licensing procedure is the test for efficacy. The complex licensing procedure has started some years ago and the first commercial product of a chemical disinfectants will be licensed and sold in 2015, and others will follow soon.

The complex and expensive licensing procedure will lead to a substantially reduced supply of available products (licensing always masquerades as being for public benefit, but the reality is that it is used as a barrier to entry for small enterprises, reducing competition and stifling innovation, thus the evolution of disinfectants as honed by the natural selection of a free market, will be slowed or stopped). It will be even more important to pick the right disinfectant for the given purpose.

Until that time interim regulations allow the use of the established disinfectants and the voluntary efficacy testing, as performed according to established guidelines, such as those from the German Veterinary Medical Society (DVG, the Verbund für angewandte Hygiene (VAH) or other national or international test protocols.

Chemical disinfectants for use in Veterinary practices

In Veterinary Practice the cleaning and disinfection of the surfaces (floor,walls and tables) in the various areas of the practice have to be performed on a regular basis, up to several times a day.

Alcohol

Rubbing alcohol, USP / Surgical spirit, B.P. is used primarily for topical application, especially following a chlorhexidine or iodine based scrub prior to surgery or is applied immediately after a dog or cat bite (when it stings, but is remarkably effective in preventing bacterial infection sequelae). It is prepared from a special denatured alcohol solution and contains approximately 70 percent by volume of pure, concentrated ethanol (ethyl alcohol) or isopropyl alcohol (isopropanol).  Individual manufacturers can use their own “formulation standards” in which the ethanol content usually ranges from 70-99% v/v. It is colorless. Instruments (e.g. thermometers) may be disinfected by immersion in surgical spirits: contamination of alcohol based solutions has rarely been reported (Weber).

Alcohols have a nonspecific mode of action, consisting mainly of disrupting any cell membrane or virus envelope, as well as denaturation and coagulation of proteins. Cells are lysed, and the cellular metabolism is disrupted. (Kampf & Kramer) The following ranking regarding the bactericidal activity has been generally established: n-propanol > isopropanol > ethanol. The bactericidal activity is also higher at 30 to 40°C than at 20 to 30°C. In terms of virucidal activity, ethanol is superior to the propanols. (Kampf and Kramer) Taken orally, they are lethal.

Alcohols, and particularly ethanol had poor activity against all non-enveloped viruses (Eterpi). Parvovirus resisted exposure to alcohol for 5 minutes (Rabenau)

Park et al (2010) evaluated the virucidal efficacy of seven hand sanitizers containing various active ingredients, such as ethanol, triclosan, and chlorhexidine, and compared their effectiveness against feline calicivirus (FCV), and a GII.4 norovirus fecal extract. Based on the results of a quantitative suspension test, only one ethanol-based product (72% ethanol, pH 2.9) and one triclosan-based product (0.1% triclosan, pH 3.0) reduced the infectivity of FCV (by ≥3.4 log units). FCV is susceptible to low pH.

Chlorine releaser – Sodium hypochlorite

Sodium hypochlorite has been used as a disinfectant for more than 100 years. It has many of the properties of an ideal disinfectant, including a broad antimicrobial activity, rapid bactericidal action, reasonable persistence in treated potable water, ease of use, solubility in water, relative stability, relative nontoxicity at use concentrations, no poisonous residuals, no color, no staining, low cost (Rutala and Weber), it is easily available, and relatively safe around cats, which is why ordinary household bleach is a widely used disinfectant both in the veterinary surgery and the home. Its rapid inactivation by contact with matter means that items must be first cleaned before they can be effectively disinfected using sodium hypochlorite however this property is a bonus where septic tanks are involved, enabling the houseowner to disinfect freely without the worry that it will harm the flora in his or her septic tank.

The efficacy of sodium hypochlorite in the cleaning and disinfection processes depends on the concentration of available chlorine and the pH of the solution. Hypochlorous acid (HOCl) is a weak acid and dissociates to the hypochlorite ion (-OCl) and proton (H+) depending on the solution pH. It is generally believed that HOCl is the active species in the germicidal action, whereas the concentration of -OCl is a key factor determining the cleaning efficiency. This implies that the optimal pH region of the germicidal activity of sodium hypochlorite differs from that of its cleaning activity (Fukuzaki). Activity is reduced by the presence of heavy metal ions, a biofilm, organic material, low temperature, low pH, or UV radiation. (Rutala and Weber).

HOCl is not very stable in solution and dissociates in Cl2, H20, and various components that are hazardous to human and animal health. In particular, low pH leads to the generation of chlorine gas, reaction with ammonium (urine) leads to the formation of chloramine. Oxidation of organic contaminants produces among others chloroform and other trihalomethanes, which are carcinogenic.

Hypochlorites are lethal to most microbes, although viruses and vegetative bacteria are more susceptible than endospore-forming bacteria, fungi, and protozoa. Clinical uses in health-care facilities include hyperchlorination of potable water to prevent Legionella colonization, chlorination of water distribution systems used in hemodialysis centers, cleaning of environmental surfaces, disinfection of laundry, local use to decontaminate blood spills, disinfection of equipment, decontamination of medical waste prior to disposal, and dental therapy. Despite the increasing availability of other disinfectants, disinfectants based on hypochlorites continue to find wide use in hospitals (Rutala and Weber)

Household bleach (0.0314, 0.0933, and 0.670% sodium hypochlorite, pH 8.36 to 10.14) produced a >5-log reduction of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium after 1 min at 25o℃. (Yang 2009)

Oxidizing agents – Hydrogen peroxide

Often used to flush directly into contaminated or infected wounds where its effervescent action and increased oxygenation retard anaerobic bacteria. Should not be used on closed wounds because of the risk of embolism. (Greene)   Used as a disinfectant for nebulizer and anaesthetic equipment. (Greene)

After 1 min at 25o C, 3% hydrogen peroxide (pH 2.75) achieved a >5-log reduction of both Salmonella Typhimurium and E. coli O157:H7. Compared with 1 min at 25 degrees C, greater reductions of Listeria monocytogenes (P < 0.05) were obtained with hydrogen peroxide treatments after 10 min at an initial temperature of 55o C. (Yang, 2009). Hydrogen peroxide is not very stable and dissociates into H20 and O2.

Potassium peroxymonosulfate

An oxidizing disinfectant usually combined with a surfactant and inorganic buffer in commercially available preparations. (Greene 2012). Highly bactericidal and virucidal, even against parvovirus (when exposed for 10 minutes). (Greene ) However, concern that it can corrode surfaces.

Greatly reduced FCV titres (Nims; Su)

Peracetic acid

Peracetic acid (also known as peroxyacetic acid, or PAA), is an organic compound with the formula CH3CO3H, it is generated in situ by some laundry detergents. It is a weaker acid than acetic acid. It is always sold in solution with acetic acid and hydrogen peroxide to maintain the stability of the peracid. Fecal indicator bacteria (Enterococcus faecium), virus indicator (male-specific (F(+)) coliphages (coliphages)), and protozoa disinfection surrogate (Bacillus subtilis spores (spores)) were tested by Park et al (2014): scanning electron microscopy observation showed that PAA targets the external layers of spores.  PAA concentrations of 5 ppm (contact time: 5 min), 50 ppm (10 min), and 3,000 ppm (5 min) were needed to achieve 3-log reduction of E. faecium, coliphages, and spores, respectively.

Peracetic acid is a potent disinfectant which is able to inactivate virtually all known pathogens. It works independent of the temperature is still active around the freezing point. However, due to the acetic acid, it is corrosive. However, additives in some commercial products reduce this side effect.

Aldehydes – Chlorhexidine

Chlorhexidine gluconate is widely used for pre-operative scrubbing of the skin of both patient and surgeon, and for hand hygiene in both wet washing and rubs. Its antimicrobial activity occurs more slowly than that of alcohols. Both chlorhexidine and povidone-iodine cause an immediate reduction in bacteria, however, the reduction when using chlorhexidine is more dramatic. In addition, povidone-iodine shows a lack of cumulative and residual activity in comparison to chlorhexidine (Jarral 2010) Jarral concludes his review of 593 papers thus: “[T]here is no evidence suggesting the use of chlorhexidine during hand scrub reduces surgical site infections, which perhaps explains why guidelines from the World Health Organization, the Centers for Disease Control and Prevention and the Association for Perioperative Practice do not recommend one specific antimicrobial over another for hand scrub.”

Multiple nosocomial outbreaks have been linked to contaminated chlorhexidine. (Weber) Most reports have been traced to the use of contaminated water to prepare diluted preparations and/or the practice of reusing bottles to dispense chlorhexidine without adequate disinfection. Although most outbreaks have occurred with solutions containing less than 2% chlorhexidine, an outbreak has been reported with solutions of 2% to 4% chlorhexidine (Weber)

Resistance to chlorhexidine and a co-selection of resistance against certain antibitotics have been described (Braoudaki and Hilton, 2004; Condell et al., 2012). Chlorhexidine was ineffective against FCV (Park et al, 2010).

Iodine/iodophors

Iodine has broad spectrum activity against gram positive and negative bacteria, fungi, protozoa and, to some extent, viruses (Greene; Weber). Destruction of bacterial spores requires moist contact for more than 15 mins (Greene). It is widely used as a pre-operative scrub on patient’s skin. It has a synergistic effect when combined with alcohol and since it is only slightly soluble in water, it tends to be dissolved in alcohol.

Iodophors are less irritating to skin than iodine compounds (Weber), and are non-staining.

Iodine surgical scrub killed MRSA (Perona) and parvovirus (Mahnel, 1977)

Quaternary ammonium compounds – Benzalkonium Chloride

The quaternary ammonium compounds are chemicals that alter the surface tension of an organism and are classed as cationic detergents. They are used for disinfection but are inactivated by organic material, soap and hard water. They are fungicidal, bactericidal and virucidal against some enveloped viruses at medium concentrations, but there is no evidence that they are effective against parvovirus. (Greene) Scorza and Lappin (2012) claimed that the compound Roccal, Winthrop Labortories, New York) were effective at inactivating Giardia cysts.

Quats are widely used in the area of food production on clean surfaces with little organic soiling. Experimentally resistance against some quats could be induced and ecotoxicologic assessments restrict their use increasingly. Quats are not recommended for general disinfection in the veterinary field.

Benzalkonium chloride was unable to eradicate a mature Salmonella biofilm (though reduced an immature one). (Corcoran)

Bacterial adaptation to quaternary ammonium compounds is documented and, worryingly, exposure to gradually increasing concentrations of this type of disinfectant results in reduced susceptibility to QACs and antibiotics as well as cross-resistance to phenicol compounds (florfenicol and chloramphenicol) in 90% of Escherichia coli strains. Extensive use of QACs at sub-inhibitory concentrations may lead to the emergence of antibiotic-resistant bacteria and may represent a public health risk. (Soumet et al, 2012)

Sodium bicarbonate

Advantages of sodium bicarbonate over the available chemical disinfectants for food contact surfaces are its safety, ready availability and low cost. Sodium bicarbonate at concentrations of 5% and above was found to be the most effective with 4 log(10) (99.99%) reduction in FCV titers on food contact surfaces within a contact time of 1 min. The virucidal efficacy of sodium bicarbonate was enhanced when it was used in combination with aldehydes or hydrogen peroxide. (Malik 2006) However, sodium bicarbonate was ineffective against Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium , even after 10 mins at 55oC. (Yang). Therefore, since bacterial reduction is important in the disinfection of food contact surfaces it is preferable to use a cat safe disinfectant (e.g. sodium hypochlorite) and thoroughly wash it off (preferably with very hot – over 60℃ – water).

Acetic acid (household vinegar)

Cheap and readily available, household vinegar (2.5 and 5% acetic acid) can be used for cleaning as well as cooking. After 1 minute at room temperature (25oC) undiluted vinegar (pH 2.58) reduced Salmonella typhimurium by over 5 logs and at a starting temperature of 55oC exposed for 10 minutes, it significantly reduced Listeria monocytogenes. (Yang 2009). However, acetic acid fumes make it fairly unpleasant to work with and it is unlikely it would be chosen in practice over a commercially available disinfectant.

Citric acid (lemon juice)

5% citric acid solutions reduced Listeria monocytogenes after 10 minutes at an initial temperature of 55oC. (Yang). However, little is known about its general disinfectant properties.

Essential oils

Essential oils have been shown to have some effect against Microsporum canis in vitro and in vivo (Mugnaini 2012) A mixture composed by 5% Origanum vulgare, 5% Rosmarinus officinalis and 2% Thymus serpillum, in sweet almond oil was administered to seven infected, symptomatic cats: four of the seven treated cats recovered.

Vázquez-Sánchez et al (2014) evaluated the potential of 19 essential oils to remove the foodborne pathogen Staphylococcus aureus from food-processing facilities: thyme oil was the most effective. Thosar et al (2013) evaluated five essential oils against four common oral pathogens of the human Staphylococcus aureusEnterococcus fecalisEscherichia coli and Candida albicans, eugenol oil (oil of cloves), peppermint oil, and tea tree oil exhibited significant inhibitory effect (Thosar). However, the antimicrobial activity of essential oils is due to a number of small terpenoids and phenol compounds (Thosar): since these are toxic to cats, essential oils should only be used under supervision of a qualified veterinary surgeon. Essential oil toxicity has been reported by Genovese et al, by Bischoff (1998) and by Khan (see table 1).

Silver compounds

Silver has been used for centuries for cutlery and dishes, with an implicit understanding of its antmicrobial action. The antibacterial, antifungal and antiviral activities of silver have generated a lot of interest in recent years. A wide range of applications has recently emerged in consumer products ranging from disinfecting medical devices, textiles, cosmetics and home appliances to water treatment. The antimicrobial action of silver or silver compounds is proportional to the bioactive silver ion (Ag(+)) released and its availability to interact with bacterial or fungal cell membranes. Silver metal and inorganic silver compounds ionize in the presence of water, body fluids or tissue exudates. The silver ion is biologically active and readily interacts with proteins, amino acid residues, free anions and receptors on mammalian and eukaryotic cell membranes. Bacterial (and probably fungal) sensitivity to silver is genetically determined and relates to the levels of intracellular silver uptake and its ability to interact and irreversibly denature key enzyme systems.  (Lansdown)

Recent advances in nanotechnology have enabled the production of pure silver, as nanoparticles, which are more efficient than silver ions. This has opened up whole new strategies to use pure silver against a wide array of pathogens, particularly multiresistant pathogens which are hard to treat with available antibiotics. (Lara 2011) It is believed that the silver nanoparticles (AgNPs) are able to interact with disulfide bonds of the glycoprotein/protein contents of microorganisms such as viruses, bacteria and fungi. (Lara 2011). AgNPs are attractive because they are non-toxic at low concentrations and have broad spectrum antibacterial action on at least 12 species of bacteria including multiresistant bacteria like Methicillin-resistant Staphylococcus aureus (MRSA), as well as multidrug-resistant Pseudomonas aeruginosa, ampicillin-resistant E. coli O157: H7 and erythromycin-resistant S. pyogenes. (Lara 2011)

There is a growing trend in developing food packaging materials with antimicrobial properties. Martínez-Abad et al (2013) incorporated silver ions into polylactide (PLA) films. The films showed strong antimicrobial efficacy against Salmonella enterica and feline calicivirus (FCV) activity in vitro, with increasing effects at higher silver concentrations. In vivo, antimicrobial activity was very much dependent on the food type and temperature: in lettuce samples incubated at 4 °C during 6 days, 4 log CFU of Salmonella was inactivated for films with 1.0 wt.% and no infectious FCV was reported under the same conditions. On paprika samples, no antiviral effect was seen on FCV infectivity whereas films showed less antibacterial activity on Salmonella.

Advancing biotechnology has enabled incorporation of ionizable silver into fabrics for clinical use to reduce the risk of nosocomial infections and for personal hygiene. (Lansdown) Although veterinary uses of silver have not yet taken off, in 2012, Woods et al reported the use of a combination of nanocrystalline silver dressing and subatmospheric pressure therapy to treat a resistant wound infection, following tumour removal and radiation therapy, in a difficult-to-manage surgical site in a cat

Chemical disinfectants against parasites

In Europe there is no uniform efficacy testing for chemical disinfectants against parasitic infections. The only guideline available is from the German Veterinary Medical Society (DVG), with the test organisms being oocysts of the coccidia species Eimeria tenella and eggs of the nematode Ascaris suum. This testing aims at the disinfection of large animal housing. The disinfectants that pass this test are exclusively products based on kresols and phenols. Both substances are considered highly toxic for cats. Products based on other active substances such as on aldehydes, peracetic acid, or others have not been tested against these agents or have been shown to be not efficacious.

Antiparasitic disinfection in cat husbandry has therefore to rely on a thorough cleaning and whenever possible heat treatment to minimize the number infectious parasites.

Toxicity of disinfectants to cats

The fastidious nature of the eating habits of the cat results in the cat being involved in fewer toxicity incidents than the dog (Mahdi; Caloni 2012; Forrester 2004; Khan et al, 2014; McLean 2012). Nevertheless, cats spend an estimated 5-25% of their waking time in grooming, so that disinfectants used in the cat’s environment (home, shelter, veterinary surgery, etc) must be safe in case inadvertent ingestion via grooming occurs. Addition sources of toxicity include transdermal absorption; (Dorman;Thompson) inhalation of irritant, or toxic, fumes; caustic burning of the paws or other areas in direct contact with disinfectant, and the tip of the tongue and oesophagus when attempting to groom the toxin off (Abou-Donia; Greene; Malik).

Possible poisoning by household products was the second most common reason (after ingestion of drugs) for telephone calls to the Kansas State University from 2009 to 2012 (Mahdi): 15.5% of 1616 calls were related to possible household product poisoning in dogs and cats, and of that 17 calls related to cats and household cleaners. (Mahdi) However, we would like to emphasise that in most reports on domestic animal poisoning, disinfectants do NOT play a major role: the major culprits being human medications, ethylene glycol, lead, lily, and topical pesticides (Antoniou; Caloni; Curti; Guitart; Hall; Hofstee; Hovda; Malik; McLean; Xavier).

For the cat, deficiency of the enzyme UDP-glucuronosyltransferase results in phenol based products are a problem (see below). Actual case reports of disinfectant toxicity in the literature are few and far between, with most published papers on toxicity in the cat having been deliberately perpetrated in the name of science. Disinfectant toxicity in cats is summarized in table 1.

Phenols

The cat shows remarkable sensitivity to the adverse effects of phenolic drugs, including acetaminophen and aspirin, as well as structurally-related toxicants found in the diet and environment. (Shrestha) This idiosyncrasy results from pseudogenization of the gene encoding UDP-glucuronosyltransferase (UGT) 1A6, the major species-conserved phenol detoxification enzyme. (Shrestha 2011) Glucuronidation is quantitatively the most important of the 6 routes by which xenobiotics (toxins) are conjugated, and therefore eliminated, from the body (Garg). Cats have a uniquely carnivorous diet and, as a result of lack of exposure to plant-based toxins (phytoalexins), have presumably lost the need to metabolise these toxins via glucuronidation, which is common in most herbivores and omnivores (Shrestha).

Table 1 – Reported toxicity of disinfectant use in cats

Disinfection Tab.2

Table 2. Recommended disinfection for use around the cat

This table shows disinfectants for use in veterinary practices and around the home, showing the most notoriously difficult to eradicate pathogens as sentinels for effectivity.

References

Abou-Donia MBTrofatter LPGraham DGLapadula DM. 1986 Electromyographic, neuropathologic, and functional correlates in the cat as the result of tri-o-cresyl phosphate delayed neurotoxicity. Toxicol Appl Pharmacol. 83(1):126-41.

Addie D.D. 2008 Control of Viral Diseases In Catteries. Kirk’s Current Veterinary Therapy XIV Edited by: John D. Bonagura, DVM, MS, DACVIM, David C. Twedt, DVM, DACVIM. Saunders, Elsevier. 1299 – 1305

Ağca H1Topaç T1Ozmerdiven GE1Celebi S2Köksal N3Hacımustafaoğlu M2Cilo BD1Sınırtaş M1Ozakın C1. 2014 Investigation of methicillin resistant Staphylococcus aureus in neonatal intensive care unit. Int J Clin Exp Med. 7(8):2209-13.

Allwood PB1Malik YSHedberg CWGoyal SM. 2004 Effect of temperature and sanitizers on the survival of feline calicivirus, Escherichia coli, and F-specific coliphage MS2 on leafy salad vegetables. J Food Prot. 67(7):1451-6.

Anderson DJ1, Gergen MFSmathers ESexton DJChen LFWeber DJRutala WA. 2013 Decontamination of targeted pathogens from patient rooms using an automated ultraviolet-C-emitting device. Infect Control Hosp Epidemiol.  34(5):466-71.

Antoniou V1Zantopoulos NTsoukali H. 1997 Fatal animal poisonings in northern Greece: 1990-1995. Vet Hum Toxicol. 39(1):35-6.

Bello A1Quinn MMPerry MJMilton DK. 2009 Characterization of occupational exposures to cleaning products used for common cleaning tasks–a pilot study of hospital cleaners. Environ Health. 8:11.

Bischoff K, Guale F.1998 Australian tea tree (Melaleuca alternifolia) oil poisoning in three purebred cats. J Vet Diagn Invest. 1998 Apr;10(2):208-10.

Braoudaki M., Hilton A. C. (2004). Adaptive resistance to biocides in Salmonella enterica and Escherichia coli O157 and cross-resistance to antimicrobial agents. J. Clin. Microbiol. 42, 73–78

Caloni FCortinovis CRivolta MDavanzo F. 2012 Animal poisoning in Italy: 10 years of epidemiological data from the Poison Control Centre of Milan. Vet Rec. 170(16):415.

Casanova LAlfano-Sobsey ERutala WAWeber DJSobsey M. 2008 Virus transfer from personal protective equipment to healthcare employees’ skin and clothing. Emerg Infect Dis.  14(8):1291-3.

Condell OIversen CCooney SPower KAWalsh CBurgess CFanning S. (2012a). Efficacy of biocides used in the modern food industry to control Salmonella—links between biocide tolerance and resistance to clinically relevant antimicrobial compounds. Appl. Environ. Microbiol. 78, 3087–3097

Corcoran MMorris DDe Lappe NO’Connor JLalor PDockery PCormican M. 2014 Commonly used disinfectants fail to eradicate Salmonella enterica biofilms from food contact surface materials. Appl Environ Microbiol.  80(4):1507-14.

Dorman DCBuck WBTrammel HLJones RDBeasley VR. 1990 Fenvalerate/N,N-diethyl-m-toluamide (Deet) toxicosis in two cats. J Am Vet Med Assoc. 196(1):100-2.

Ebner W1Eitel AScherrer MDaschner FD. 2000 Can household dishwashers be used to disinfect medical equipment? J Hosp Infect. 45(2):155-9.

Ernst JVLindsay DSCurrent WL. 1985 Control of Isospora suis-induced coccidiosis on a swine farm. Am J Vet Res. 46(3):643-5.

Eterpi M1McDonnell GThomas V. 2009 Disinfection efficacy against parvoviruses compared with reference viruses. J Hosp Infect. 73(1):64-70.

Forrester MB1Stanley SK. 2004 Patterns of animal poisonings reported to the Texas Poison Center Network: 1998-2002. Vet Hum Toxicol. 46(2):96-9.

Fukuzaki S. 2006 Mechanisms of actions of sodium hypochlorite in cleaning and disinfection processes. Biocontrol Sci.  11(4):147-57.

Fuller C, Besser S, Savage J, McAteer J, Stone S, Michie S. 2014 Application of a theoretical framework for behavior change to hospital workers’ real-time explanations for noncompliance with hand hygiene guidelines. Am J Infect Control. 42(2):106-10.

Garg SK. 2007 General Toxicology. In Veterinary Toxicology Editor Garg SK. CBS Publishers & Distributors, 4596/1A, 11 Darya Ganj, New Delhi, 110 002 India 1-36

Genovese AG1McLean MKKhan SA. 2012 Adverse reactions from essential oil-containing natural flea products exempted from Environmental Protection Agency regulations in dogs and cats.  Vet Emerg Crit Care (San Antonio).  22(4):470-5.

Gerba CP1Kennedy D. 2007 Enteric virus survival during household laundering and impact of disinfection with sodium hypochlorite. Appl Environ Microbiol. 73(14):4425-8.

Graczyk TK1Cranfield MRFayer RBixler H. 1999 House flies (Musca domestica) as transport hosts of Cryptosporidium parvum. Am J Trop Med Hyg. 61(3):500-4.

Guitart R1Manosa SGuerrero XMateo R. 1999 Animal poisonings: the 10-year experience of a veterinary analytical toxicology laboratory. Vet Hum Toxicol. 41(5):331-5.

Greene CE, Weese JS, Calpin JP.   2012 Environmental factors in infectious disease. Infectious Diseases of the Dog and Cat. 4th edition. Editor: Greene, Craig. Published by W.B. Saunders Elsevier Company, 11830 Westline Industrial Drive, St. Louis, Missouri 63146, USA. ISBN 978-1-4160-6130-41078-1100

Honisch M1Stamminger RBockmühl DP.2014 Impact of wash cycle time, temperature and detergent formulation on the hygiene effectiveness of domestic laundering. J Appl Microbiol. 2014 Dec;117(6):1787-97.

Hanig JPKrop SMorrisonColson SH. 1976 Observations on hexachlorophene-induced paralysis in the cat and its antagonism by hypertonic urea. Proc Soc Exp Biol Med. 152(2):165-9.

Hofstee AW. 1989 [Acute poisoning in animals in The netherlands in the period 1985-1988]. Tijdschr Diergeneeskd. 1989 Nov 15;114(22):1154-8.

Hall, K. (2008). Toxin exposures and treatments: a survey of practicing veterinarians. Kirk’s current veterinary therapy XIV. J. D. Bonagura and D. C. Twedt. Philadelphia, Pa, Elsevier Saunders: 95-99.

Hovda, L. R. (2008). Toxin exposures in small animals. Kirk’s current veterinary therapy XIV. J. D. Bonagura and D. C. Twedt. Philadelphia, Pa, Elsevier Saunders: 92-94.

Jarral OAMcCormack DJIbrahim SShipolini AR. 2011 Should surgeons scrub with chlorhexidine or iodine prior to surgery? Interact Cardiovasc Thorac Surg.  12(6):1017-21.

Kampf GKramer A. 2004 Epidemiologic background of hand hygiene and evaluation of the most important agents for scrubs and rubs. Clin Microbiol Rev. 17(4):863-93

Kampf G1Grotheer DSteinmann J. 2005 Efficacy of three ethanol-based hand rubs against feline calicivirus, a surrogate virus for norovirus. J Hosp Infect. 60(2):144-9.

Khan SA. 2012 Common reversal agents/antidotes in small animal poisoning. Vet Clin North Am Small Anim Pract. 42(2):403-6, ix.

Khan SA1McLean MKSlater MR. 2014 Concentrated tea tree oil toxicosis in dogs and cats: 443 cases (2002-2012). J Am Vet Med Assoc. 244(1):95-9.

Lai PCoulson CPothier DDRutka J. 2011 Chlorhexidine ototoxicity in ear surgery, part 1: review of the literature. J Otolaryngol Head Neck Surg. 40(6):437-40.

Lansdown AB. 2006 Silver in health care: antimicrobial effects and safety in use. Curr Probl Dermatol. 33:17-34.

Lara HH1Garza-Treviño ENIxtepan-Turrent LSingh DK. 2011 Silver nanoparticles are broad-spectrum bactericidal and virucidal compounds. J Nanobiotechnology.  9:30.

Mahdi A, Van der Merwe D. 2013 Dog and cat exposures to hazardous substances reported to the Kansas State Veterinary Diagnostic Laboratory: 2009-2012. J Med Toxicol. 9(2):207-11.

Mahnel H. 1977 Studies on inactivation of viruses in drinking and surface water. A contribution to the decontamination of water by field methods (author’s transl). Zentralbl Bakteriol Orig B. 1165(5-6):527-38.

Malik R, Ward MP, Seavers A, Fawcett A, Bell E, Govendir M, Page S. 2010 Permethrin spot-on intoxication of cats Literature review and survey of veterinary practitioners in Australia. J Feline Med Surg. 12(1):5-14

Malik YS1Allwood PBHedberg CWGoyal SM. 2006 Disinfection of fabrics and carpets artificially contaminated with calicivirus: relevance in institutional and healthcare centres. J Hosp Infect. 63(2):205-10.

Malik YS1Goyal SM. 2006 Virucidal efficacy of sodium bicarbonate on a food contact surface against feline calicivirus, a norovirus surrogate. Int J Food Microbiol. 109(1-2):160-3.

Martínez-Abad A1Ocio MJLagarón JMSánchez G. 2013 Evaluation of silver-infused polylactide films for inactivation of Salmonella and feline calicivirus in vitro and on fresh-cut vegetables. Int J Food Microbiol. 162(1):89-94.

McLean MK, Hansen SR. 2012 An overview of trends in animal poisoning cases in the United States: 2002-2010. Vet Clin North Am Small Anim Pract. 42(2):219-28

Möstl K, Egberink H, Addie D, Frymus T, Boucraut-Baralon C, Truyen U, Hartmann K, Lutz H, Gruffydd-Jones T, Radford AD, Lloret A, Pennisi MG, Hosie MJ, Marsilio F, Thiry E, Belák S, Horzinek MC. 2013 Prevention of infectious diseases in cat shelters: ABCD guidelines. J Feline Med Surg. 15(7):546-54

Mtapuri-Zinyowera S1Midzi NMuchaneta-Kubara CESimbini TMduluza T. 2009 Impact of solar radiation in disinfecting drinking water contaminated with Giardia duodenalis and Entamoeba histolytica/dispar at a point-of-use water treatment. J Appl Microbiol.  106(3):847-52.

Mugnaini L1Nardoni SPinto LPistelli LLeonardi MPisseri FMancianti F. 2012 In vitro and in vivo antifungal activity of some essential oils against feline isolates of Microsporum canis. J Mycol Med. 22(2):179-84.

Nims R1Plavsic M. 2013 Inactivation of caliciviruses. Pharmaceuticals (Basel). 6(3):358-92.

Ossowski B1Duchmann U. 1997 [Effect of domestic laundry processes on mycotic contamination of textiles]. Hautarzt. 48(6):397-401.

Park E1Lee C1Bisesi M1Lee J2. 2014 Efficiency of peracetic acid in inactivating bacteria, viruses, and spores in water determined with ATP bioluminescence, quantitative PCR, and culture-based methods. J Water Health.  12(1):13-23.

Park GW1Barclay LMacinga DCharbonneau DPettigrew CAVinjé J. 2010 Comparative efficacy of seven hand sanitizers against murine norovirus, feline calicivirus, and GII.4 norovirus. J Food Prot. 73(12):2232-8.

Park Y. 2014 New paradigm shift for the green synthesis of antibacterial silver nanoparticles utilizing plant extracts. Toxicol Res.  30(3):169-78.

Perona PJ1Johnson AJPerona JPIssa KKapadia BHBonutti PMMont MA. 2013 Effectiveness of various hospital-based solutions against community- acquired methicillin-resistant Staphylococcus aureus. J Long Term Eff Med Implants. 23(1):23-9.

Pruss A, Göbel UB, Pauli G, Kao M, Seibold M, Mönig HJ, Hansen A, von Versen R. 2003 Peracetic acid-ethanol treatment of allogeneic avital bone tissue transplants–a reliable sterilization method. Ann Transplant. 2003;8(2):34-42.

Rabenau HF, Steinmann J, Rapp I, Schwebke I, Eggers M. 2014 Evaluation of a virucidal quantitative carrier test for surface disinfectants. PLoS One. 27;9(1)

Reis EG, Gremião ID, Kitada AA, Rocha RF, Castro VS, Barros MB, Menezes RC, Pereira SA, Schubach TM. 2012 Potassium iodide capsule treatment of feline sporotrichosis. J Feline Med Surg. 14(6):399-404.

Rousseaux CGSmith RANicholson S. 1986 Acute Pinesol toxicity in a domestic cat. Vet Hum Toxicol. 1986 Aug;28(4):316-7.

Rutala WA1Weber DJ. 1997 Uses of inorganic hypochlorite (bleach) in health-care facilities. Clin Microbiol Rev.  10(4):597-610.

Shah, P. C., S. Krajden, J. Kane, and R. C. Summerbell. 1988. Tinea corporis caused by Microsporum canis: report of a nosocomial outbreak. Eur. Epidemiol. 4:33–38.

Sanekata T, Fukuda T, Miura T, Morino H, Lee C, Maeda K, Araki K, Otake T, Kawahata T, Shibata T. 2010 Evaluation of the antiviral activity of chlorine dioxide and sodium hypochlorite against feline calicivirus, human influenza virus, measles virus, canine distemper virus, human herpesvirus, human adenovirus, canine adenovirus and canine parvovirus. Biocontrol Sci. 2010 Jun;15(2):45-9.

Scorza V, Lappin M. 2012 Enteric protozoal infections. Infectious Diseases of the Dog and Cat. 4th edition. Editor: Greene, Craig. Published by W.B. Saunders Elsevier Company, 11830 Westline Industrial Drive, St. Louis, Missouri 63146, USA. ISBN 978-1-4160-6130-41078-1100 785-801

Scott JGWarren WCBeukeboom LWBopp DClark AGGiers SDHediger MJones AKKasai SLeichter CALi MMeisel RPMinx PMurphy TDNelson DRReid WRRinkevich FDRobertson HMSackton TBSattelle DBThibaud-Nissen FTomlinson Cvan de Zande LWalden KWilson RKLiu N Genome of the house fly, Musca domestica L., a global vector of diseases with adaptations to a septic environment. Genome Biol. 2014 Oct 14;15(10):466.

Shrestha B, Reed JM, Starks PT, Kaufman GE, Goldstone JV, Roelke ME, O’Brien SJ, Koepfli KP, Frank LG, Court MH. 2011 Evolution of a major drug metabolizing enzyme defect in the domestic cat and other felidae: phylogenetic timing and the role of hypercarnivory. PLoS One 6(3):e18046

Shukla Y 2007 Chemicals, drugs and plants-induced carcinogenicity and genotoxicity. In Veterinary Toxicology Editor Garg SK. CBS Publishers & Distributors, 4596/1A, 11 Darya Ganj, New Delhi, 110 002 India   269-280

Soumet C1Fourreau ELegrandois PMaris P. 2012 Resistance to phenicol compounds following adaptation to quaternary ammonium compounds in Escherichia coli. Vet Microbiol.  158(1-2):147-52.

Ståhl Wernersson E1Johansson EHåkanson H. 2004 Cross-contamination in dishwashers. J Hosp Infect. 2004 Apr;56(4):312-7.

Standaert, S. M., R. H. Hutcheson, and W. Schaffner. 1994. Nosocomial transmission of Salmonella gastroenteritis to laundry workers in a nursing home. Infect. Control Epidemiol. 15:22–26.

Su X1D’Souza DH. 2012 Inactivation of human norovirus surrogates by benzalkonium chloride, potassium peroxymonosulfate, tannic acid, and gallic acid. Foodborne Pathog Dis. 9(9):829-34.

Steinmann J. 2004 Surrogate viruses for testing virucidal efficacy of chemical disinfectants. J Hosp Infect. 56 Suppl 2:S49-54.

Swathy JR1Sankar MU2Chaudhary A2Aigal S1Anshup2Pradeep T. 2014 Antimicrobial silver: An unprecedented anion effect. Sci Rep. 4:7161.

Curti R1Kupper JKupferschmidt HNaegeli H. 2009 A retrospective study of animal poisoning reports to the Swiss Toxicological Information Centre (1997 – 2006). Schweiz Arch Tierheilkd. 151(6):265-73.

Thompson JPSenior DFPinson DMMoriello KA. 1987 Neurotoxicosis associated with the use of hexachlorophene in a cat. J Am Vet Med Assoc. 190(10):1311-2.

Thosar N1Basak S2Bahadure RN3Rajurkar M2. 2013 Antimicrobial efficacy of five essential oils against oral pathogens: An in vitro study. Eur J Dent. 7(Suppl 1):S71-7.

Umit UM1Sina M2Ferhat Y2Yasemin P3Meltem K2Ozdemir AA2. 2014 Surgeon behavior and knowledge on hand scrub and skin antisepsis in the operating room. J Surg Educ.  71(2):241-5.

Xavier FG1Kogika MMde S. 2002 Common causes of poisoning in dogs and cats in a Brazilian veterinary teaching hospital from 1998 to 2000. Vet Hum Toxicol. 44(2):115-6.

Vázquez-Sánchez D1Cabo ML1Rodríguez-Herrera JJ2. 2014 Antimicrobial activity of essential oils against Staphylococcus aureus biofilms. Food Sci Technol Int. 2014 Oct 3. pii:

Weber DJ, Rutala WA, Sickbert-Bennett EE. 2007 Outbreaks associated with contaminated antiseptics and disinfectants. Antimicrob Agents Chemother. 51(12):4217-24.

Woods S,  de Castro Marques AIRenwick MGArgyle SAYool DA. 2012 Nanocrystalline silver dressing and subatmospheric pressure therapy following neoadjuvant radiation therapy and surgical excision of a feline injection site sarcoma. J Feline Med Surg.  14(3):214-8.

Yang H1Kendall PAMedeiros LSofos JN. 2009 Inactivation of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella typhimurium with compounds available in households. J Food Prot.  72(6):1201-8.

Zhu JJ1, Zeng XP, Berkebile D, DU HJ, Tong Y, Qian K. 2009 Efficacy and safety of catnip (Nepeta cataria) as a novel filth fly repellent. Med Vet Entomol.  23(3):209-16.