Immediate and residual antifungal activity of compounds used for whole body and adjuvant topical therapy against Microsporum canis: an in vitro study.

BACKGROUND: Topical antifungal therapy is recommended to disinfect hairs of dermatophyte-infected animals. OBJECTIVE: To determine the immediate and residual (24, 48 and 72 h) antifungal activity of commonly used products for focal (n = 11) and whole body application (n = 3). ANIMALS: Hair samples from naturally infected kittens. METHODS AND MATERIALS: Immediate antifungal activity was assessed using isolated infected spores. In a more robust challenge, toothbrushes containing whole infected hairs were repeatedly treated with products until culture-negative. Residual activity was determined by treating 0.04 g of uninfected hair with test products, allowing hairs to dry and then plating hairs onto fungal culture plates inoculated with Microsporum canis. Residual activity was assessed at 24, 48 and 72 h post-treatment. RESULTS: All products showed good efficacy against isolated infected spores. Two products required three treatments to disinfect whole infected hairs (miconazole 0.2% and ketoconazole 0.15%); all other products were efficacious after one treatment. For each product residual activity at 24, 48 and 72 h was similar. For the whole body products, lime sulfur and enilconazole showed residual activity, but as expected none was detected for 2% miconazole nitrate/ 2% chlorhexidine shampoo. For focal therapy products, residual activity was detected for clotrimazole 1%, terbinafine 1%, miconazole at 0.2, 1 or 2% (with or without chlorhexidine), climbazole 0.5% with chlorhexidine gluconate, and ketoconazole 1% with chlorhexidine gluconate. A ketoconazole 0.15% with 0.15% chlorhexidine gluconate showed no residual activity. CONCLUSIONS AND CLINICAL IMPORTANCE: Findings support twice weekly application of enilconazole and lime sulfur, and application of adjuvant focal topical therapy daily or every other day.

Decontamination of 70 foster family homes exposed to Microsporum canis infected cats: a retrospective study.

BACKGROUND: Dermatophytosis is a superficial fungal skin disease of animals. A key part of treatment is cleaning and disinfection of the environment to prevent false-positive results due to fomite carriage. Furthermore, there is a perception in the lay literature that decontamination of homes is difficult or impossible. CLINICAL SUMMARY: Data from a 10 year period identified 70 foster family homes where Microsporum canis infected cats had lived for varying periods of time. Mechanical debris was removed from the rooms housing the cats, the areas cleaned with over-the-counter household detergents, rinsed and hard surfaces disinfected with 1:100 concentration household bleach or accelerated hydrogen peroxide. Thirty-eight homes were completely decontaminated after one cleaning post removal or cure of the cat. Of the remaining homes, decontaminated was achieved after one (n=28), two (n=2) or three (n=1) additional cleanings. Complete decontamination was not possible in one home; the foster family was admittedly noncompliant. There was no evidence of disease transmission to other animals or people. CONCLUSIONS: Environmental decontamination is not difficult in homes exposed to M. canis and can be accomplished with established procedures.

Mechanical washing of pet food bowls is effective for Microsporum canis decontamination.

BACKGROUND: Dermatophyte lesions are common on the face of animals and pet food bowls can become contaminated by direct contact with the facial lesions. Owners are concerned about appropriate decontamination and yet worried about exposing pets to disinfectant residues. OBJECTIVE: To determine the efficacy of mechanical cleaning alone for decontamination of contaminated pet food dishes. METHODS AND MATERIALS: An isolated infective spore suspension of Microsporum canis was used to experimentally contaminate metal (n = 4), plastic (n = 4) and glass (n = 4) pet food bowls. The experiment was repeated twice, first with just the spore suspension, and then with a mixture of spore suspension and canned pet food. The bowls were soaked in hot water (34°C) with a generic dish soap in a sink for two minutes, scrubbed using a dishwashing brush until visibly clean or for 2 min, rinsed, allowed to air-dry and then cultured. Fungal culture samples were collected using disposable dust cloths. Environmental fungal cultures were obtained from the sink after routine mechanical cleaning with a sudsy detergent. RESULTS: No environmental contamination was detected. The results of both experiments were similar. All bowls (n = 24) were fungal culture positive for M. canis before washing and all were completely decontaminated with mechanical washing alone. CONCLUSIONS AND CLINICAL IMPORTANCE: Mechanical washing alone can decontaminate pet food bowls exposed to naturally infective material. Dishes should be soaked in hot sudsy water to loosen organic debris, scrubbed until visibly clean and then rinsed. Owners should wear dishwashing gloves for personal protection.

Use of a commercial qPCR assay in 52 high risk shelter cats for disease identification of dermatophytosis and mycological cure.

BACKGROUND: qPCR is used to test for dermatophytosis. OBJECTIVES: To determine the clinical usefulness of a commercial qPCR for confirming dermatophytosis in lesional cats, and the clinical usefulness of the qPCR Microsporum spp. and/or M. canis assay for confirming mycological cure. ANIMALS: Fifty two shelter cats with skin lesions. METHODS: qPCR testing of toothbrush fungal culture samples of lesions. RESULTS: qPCR and fungal culture (FC) matched in 49 of 52 cats. The qPCR correctly identified 45 of 46 and two of four cats with M. canis and Trichophyton spp. infections, respectively. qPCR correctly identified two cats as not infected. No evidence of cross reactivity was noted. The Microsporum spp. qPCR assay was positive in 45 of 46 (97.8%) of infected cats. Results were positive on both Microsporum spp. and M. canis assays in 29 of 45 cats. No cat had a positive qPCR result for M. canis alone. Mycological cure was defined as two negative fungal cultures. There were 92 negative FC from the 46 treated cats and qPCR assay for Microsporum spp. and M. canis was negative in 68 of 92 (73.1%) and 79 of 92 (85.9%) samples, respectively. The number of cats correctly identified with mycological cure via qPCR was 30 of 46 (65.2%) and 39 of 46 (84.8%) cats for the Microsporum spp. and M. canis assays, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: The commercial qPCR assay was a reliable test for confirming disease. The qPCR Microsporum spp. assay was more useful for initial disease confirmation; while the qPCR M. canis assay was more useful for determining mycological cure.

Diagnosis and treatment of dermatophytosis in dogs and cats.: Clinical Consensus Guidelines of the World Association for Veterinary Dermatology.

BACKGROUND: Dermatophytosis is a superficial fungal skin disease of cats and dogs. The most common pathogens of small animals belong to the genera Microsporum and Trichophyton. It is an important skin disease because it is contagious, infectious and can be transmitted to people. OBJECTIVES: The objective of this document is to review the existing literature and provide consensus recommendations for veterinary clinicians and lay people on the diagnosis and treatment of dermatophytosis in cats and dogs. METHODS: The authors served as a Guideline Panel (GP) and reviewed the literature available prior to September 2016. The GP prepared a detailed literature review and made recommendations on selected topics. The World Association of Veterinary Dermatology (WAVD) provided guidance and oversight for this process. A draft of the document was presented at the 8th World Congress of Veterinary Dermatology (May 2016) and was then made available via the World Wide Web to the member organizations of the WAVD for a period of three months. Comments were solicited and posted to the GP electronically. Responses were incorporated by the GP into the final document. CONCLUSIONS: No one diagnostic test was identified as the gold standard. Successful treatment requires concurrent use of systemic oral antifungals and topical disinfection of the hair coat. Wood's lamp and direct examinations have good positive and negative predictability, systemic antifungal drugs have a wide margin of safety and physical cleaning is most important for decontamination of the exposed environments. Finally, serious complications of animal-human transmission are exceedingly rare.

Dinotefuran/pyriproxyfen/permethrin pemphigus-like drug reaction in three dogs.

BACKGROUND: Pemphigus foliaceus (PF) can occur spontaneously or as a reaction pattern associated with cutaneous adverse drug reactions. HYPOTHESIS/OBJECTIVES: To provide clinical, histological and immunological assessments of three dogs that developed cutaneous adverse drug reactions following application of a topical flea and tick control product, which contained dinotefuran, pyriproxyfen and permethrin. ANIMALS: Three client-owned dogs. RESULTS: The dogs exhibited rapid onset of papules, pustules and crusts at the site of application of the flea control product. In two dogs, the lesions became generalized, while the third exhibited a localized phenotype. Both dogs with generalized lesions required immunosuppressive treatment; one achieved remission after 1 year of treatment and one was euthanized due to adverse effects of glucocorticoids. The dog with a localized phenotype was treated with topical glucocorticoids exclusively and achieved remission after 10 months. Histology revealed subcorneal pustular dermatitis, with acantholysis of keratinocytes and focal to multifocal full-thickness epidermal necrosis. These features are similar to those previously reported for pesticide-triggered and spontaneous PF. Tissue-bound IgG was detected in two of three dogs, and autoantibodies targeting canine desmocollin-1 were identified in the serum of the one dog from which a sample was available. CONCLUSIONS AND CLINICAL IMPORTANCE: Cutaneous adverse drug reaction caused by a flea control product containing dinotefuran, pyriproxyfen and permethrin closely resembled those reported for other pesticide-associated PF-like cutaneous adverse drug reactions. Although it appears to be a rare entity, clinicians and pathologists should be aware of the potential for flea and tick control products to trigger PF-like reactions.

Efficacy of disinfectants containing accelerated hydrogen peroxide against conidial arthrospores and isolated infective spores of Microsporum canis and Trichophyton sp.

BACKGROUND: Accelerated hydrogen peroxide is a proprietary disinfectant formulation that is available for both commercial and home use and is labelled as antifungal. HYPOTHESIS/OBJECTIVES: To determine the antifungal efficacy of accelerated hydrogen peroxide disinfectants against Microsporum and Trichophyton spp. METHODS: Three products formulated as ready to use and three concentrates were used. Concentrates were tested at dilutions of 1:8, 1:16 (recommended dilution) and 1:32. One product was a surgical instrument disinfectant. Sterile water, sodium hypochlorite (1:32 dilution) and over-the-counter 3% hydrogen peroxide were used as controls. Conidial suspensions contained ~9.6 × 10(5) /mL Microsporum canis, ~1.0 × 10(7) /mL M. gypseum or ~2.0 × 10(7) /mL Trichophyton sp. and were tested at 1:10 dilution. Isolated infective spore suspensions of M. canis from an untreated cat and T. erinacei from an untreated hedgehog were tested at 1:10, 1:5 and 1:1 spore-to-disinfectant dilutions. RESULTS: Too many colonies to count were present on untreated control plates. Accelerated hydrogen peroxide and household hydrogen peroxide inhibited growth of both pathogens in conidial (1:10 dilution) and spore suspensions (1:10, 1:5 and 1:10 dilution). There was no lack of efficacy of products that were >12 months old. CONCLUSIONS AND CLINICAL IMPORTANCE: Accelerated hydrogen peroxide products are an option for environmental disinfection of surfaces exposed to M. canis and Trichophyton sp. after appropriate gross decontamination and mechanical cleaning with a detergent. The results from conidial testing were identical to those of isolated infected spore testing, which suggests that accelerated hydrogen peroxide products with label claim as antifungal against Trichophyton mentagrophytes may be suitable as an alternative disinfectant to sodium hypochlorite.

Five observations of a third morphologically distinct feline Demodex mite.

BACKGROUND: Feline demodicosis is caused by infestation with Demodex cati and/or Demodex gatoi. These two mites have distinctive morphological appearances. OBJECTIVES: To describe five observations of a morphologically distinct feline Demodex mite in 10 cats. All cats were in or adopted from an animal shelter. RESULTS: A mite with blunted ends longer than D. gatoi but shorter than D. cati was observed in one or multiple cats from animal shelters. Mean mite size was 139 ± 4.5 µm (n = 41 mites). Similar features among the cases included a history of recent recovery or presence of concurrent illness at the time of diagnosis. Pruritus was variable. Hairs were easily epilated in large amounts, and mites were found on either skin scrapings or hair trichograms; mites were most commonly found on the proximal third of hairs examined via trichogram. CLINICAL IMPORTANCE: Reports of this mite are uncommon but when present tend to be in cats with concurrent illnesses. Awareness of this mite morphology will hopefully provide other investigators with specimens for molecular testing to determine whether this is a third species or a variant of D. gatoi or D. cati.

Efficacy of eight commercial disinfectants against Microsporum canis and Trichophyton spp. infective spores on an experimentally contaminated textile surface.

BACKGROUND: An important part of treatment of dermatophytosis is the removal of infective material and decontamination of the environment. It is recognized that the role of disinfectants is to kill infective material not removed during the mechanical removal of debris and gross cleaning steps. A widely used disinfectant in the home is a dilute solution of sodium hypochlorite. HYPOTHESIS/OBJECTIVES: To determine whether over-the-counter products, particularly ready-to-use formulations, with label claim as fungicidal are effective against Microsporum or Trichophyton spores isolated from cat hair. METHODS: Eight commercial disinfectants were tested in vitro for fungicidal efficacy using three different trials and a 10 min contact time, as follows: a standard 1:10 spore dilution suspension test; 1 and 5 mL of disinfectant solution applied to contaminated gauze fabric; and, to simulate home use, one and five sprays of disinfectant applied to contaminated gauze. Good efficacy was defined as a product that completely inhibited growth. RESULTS: All products completely inhibited growth in the suspension test. Four of eight products showed complete inhibition of growth of both pathogens on the textile test after 1 mL or one spray; however, all eight products showed complete inhibition of pathogen growth after 5 mL or five sprays. CONCLUSIONS AND CLINICAL IMPORTANCE: Aggressive removal of contaminated material followed by thorough application of commercial ready-to-use disinfectants labelled as fungicidal against Trichophyton mentagrophytes are alternatives to dilute sodium hypochlorite.

Treatment of shelter cats with oral terbinafine and concurrent lime sulphur rinses.

BACKGROUND: Dermatophytosis is an important contagious and infectious skin disease in an animal shelter. Itraconazole is the commonly used systemic antifungal drug, but it is expensive in some countries and, at times, difficult to obtain. Terbinafine is a fungicidal allylamine with documented in vitro and in vivo efficacy against Microsporum canis in pet cats and in cats with experimental infections. HYPOTHESIS/OBJECTIVES: To describe the use of oral terbinafine for the treatment of M. canis dermatophytosis in shelter cats. METHODS: The response to treatment of 85 shelter cats with naturally occurring M. canis dermatophytosis was monitored by examination, weekly toothbrush fungal cultures and the number of colony-forming units on fungal culture plates. Cats were treated with either 14 (n = 21) or 21 days (n = 64) of terbinafine per os (p.o.) along with concurrent twice weekly lime sulphur rinses and daily environmental disinfection. RESULTS: Cats treated with 14 days of terbinafine p.o. showed an initial response to therapy but by week 6 had relapsed and required rescue therapy with a course of itraconazole (10 mg/kg p.o.) to obtain a cure. Cats treated with 21 days of terbinafine p.o. showed a response to treatment similar to published reports using itraconazole p.o. for 21 days. The mean and median number of days to mycological cure was 22.70 (range 13-39). Terbinafine was well tolerated. None of the cats developed oral lesions postgrooming of lime sulphur rinses. CLINICAL SIGNIFICANCE: Where itraconazole is not available, substitution with terbinafine in established protocols may allow shelters to treat cats that otherwise would go untreated.

A case of apparent canine erysipeloid associated with Erysipelothrix rhusiopathiae bacteraemia.

BACKGROUND: Erysipelothrix rhusiopathiae is a Gram-positive facultative anaerobe found worldwide and is most commonly associated with skin disease in swine, while anecdotal reports of cases in dogs have been associated with endocarditis. HYPOTHESIS/OBJECTIVES: Clinicians should consider systemic infectious diseases as a potential cause of erythematous skin lesions. ANIMALS: A 5-year-old female spayed Labrador retriever presented with lethargy, anorexia and erythematous skin lesions while receiving immunosuppressive therapy for immune-mediated haemolytic anaemia. Four days prior to presentation, the dog had chewed on a raw turkey carcase. METHODS: Complete blood count, serum chemistry profile, urinalysis and blood cultures. RESULTS: Blood cultures yielded a pure growth of E. rhusiopathiae serotype 1b. Amoxicillin 22 mg/kg orally twice daily for 2 weeks and discontinuation of azathioprine resulted in remission of fever and skin lesions. CONCLUSIONS AND CLINICAL IMPORTANCE: This report is the first documentation, to the best of the authors' knowledge, of Erysipelothrix infection, a known zoonosis, in an immunosuppressed dog, highlighting the need for infectious disease monitoring in patients receiving such therapy. This information may also help educate veterinarians to include Erysipelothrix infection as a differential diagnosis in dogs with fever and skin lesions, as well as the role of blood cultures in diagnosing this disease.

Efficacy of eight commercial formulations of lime sulphur on in vitro growth inhibition of Microsporum canis.

Lime sulphur is a common topical treatment for dermatophytosis in animals. Until recently, a single veterinary lime sulphur formulation was available. The purpose of this study was to compare the efficacy of eight lime sulphur products for in vitro growth inhibition of Microsporum canis using the isolated infected spore model. Infective M. canis spores were isolated from hairs collected from untreated cats. Hairs were macerated in Triton-X solution and isolated according to a previously published protocol. Equal volumes of spore suspension and lime sulphur solutions were incubated for 5 min and plated onto modified BBL™ Mycosel™ agar (Becton, Dickinson and Company; Sparks, MD, USA) plates. Five plates were inoculated for each sample solution. Distilled water and bleach were used as controls. Colony forming units were counted daily for 21 days; positive control plates contained >300 colony forming units/plate. Seven of the products were supplied as concentrates and they were tested at the manufacturer's recommended dilution, twice label concentration and half label concentration. A prediluted product SulfaDip(®) (Trask Research, Inc.; Daluca, GA, USA) was tested at the label and half label concentration. All veterinary products formed recommended treatment dilutions of 3% sulphurated lime solution except one (LymDyp(®), IVX Animal Health Inc.; St Joseph, MO, USA), which formed a 2.4% sulphurated lime solution. Results of the study showed complete growth inhibition of M. canis spores by all products at all dilutions tested. These results indicate that all tested lime sulphur-containing products were equivalent. Field studies are needed to test product equivalency in vivo.

Use of itraconazole and either lime sulphur or Malaseb Concentrate Rinse ® to treat shelter cats naturally infected with Microsporum canis: an open field trial.

In an open non-randomized study, 90 cats with severe dermatophytosis were treated with 21 days of oral itraconazole at 10 mg/kg and one of three topical antifungal rinses applied twice weekly: lime sulphur (LSO); reformulated lime sulphur with an odour-masking agent (LSR); or a 0.2% miconazole nitrate and 0.2% chlorhexidine gluconate rinse (MC). Weekly examinations and fungal cultures were used to monitor the cats' response to therapy. If at day 42 of treatment cats were still strongly fungal culture positive and/or developing new lesions, they were retreated with oral itraconazole and LSO. Cats were not prevented from licking the solutions and none developed oral ulcerations. Thirty-one cats were treated with LSO, 27 with LSR and 32 with MC. The median number of days to cure was 30 (range 10-69 days) and 34 (range 23-80 days) for LSO and LSR, respectively. Thirty-two cats were treated with MC, and 13 of 32 cats required repeat treatment because of persistent culture-positive status and development of new lesions. Median number of days of treatment for the 19 cats that cured with MC was 48 (range 14-93 days). When the number of days to cure was compared between the groups, there was a significant difference between cats treated with LSO and LSR (P=0.029) and cats treated with LSO and MC (P=0.031), but no significant difference between the number of days to cure for cats treated with LSR and MC (P=0.91).

One vs two negative fungal cultures to confirm mycological cure in shelter cats treated for Microsporum canis dermatophytosis: a retrospective study.

OBJECTIVES: The aim of this study was to determine how often one negative fungal culture (FC) was indicative of mycological cure (MC) when compared with two negative consecutive FCs in cats treated for Microsporum canis dermatophytosis. METHODS: In this retrospective study, weekly FC data from shelter cats treated for M canis dermatophytosis were reviewed. RESULTS: Complete records from 371 cats were reviewed. The first negative FC was indicative of MC in 335 (90.3%) cats. In this group, all cats were otherwise healthy and either had obvious lesions (n = 237) or no lesions or evidence of resolving lesions (n = 98). In the 36 cats in which the first negative culture was not indicative of MC, there were two clinical subgroups. The first consisted of healthy but lesional cats (n = 19) that had one negative FC within the first 3 weeks of treatment followed by one or more positive FCs. The most likely explanation was sampling error. These cats went on to cure and the next negative FC was indicative of MC. In the second clinical group, cats were lesional but had concurrent medical problems (n = 17). These cats showed an initial good response to treatment (lesion resolution and an initial negative FC). However, this negative FC was followed by at least one strongly positive FC (>10 colony-forming units/plate) before proceeding to cure. These cats took the longest time to cure (mean 11 weeks; range 8-28 weeks). MC occurred after resolution of the concurrent health issues. There was very good agreement between using one negative FC vs two negative FCs for the determination of MC in healthy cats (kappa = 0.903). CONCLUSIONS AND RELEVANCE: In cats where there has been high compliance with environmental cleaning, as well as topical and systemic treatment recommendations, two consecutive negative FCs may not be necessary to determine MC. The first negative FC in an otherwise healthy cat is likely indicative of MC. Good sampling technique is needed to avoid false-negative FC results.

Trichophyton species and Microsporum gypseum infection and fomite carriage in cats from three animal shelters: a retrospective case series.

OBJECTIVES: The goal of this retrospective case series was to report on the clinical aspects of confirmed Trichophyton species and Microsporum gypseum infections in cats from three animal shelters. METHODS: This was an observational retrospective study. Fungal culture and treatment data from three animal shelters was retrospectively reviewed to identify cats with dermatophytosis caused by Trichophyton species or M gypseum. RESULTS: Among the three shelters only four cats were diagnosed with M gypseum dermatophytosis. With respect to Trichophyton species infections, there were six cases identified and treated in a 1 year period in one shelter, 13 cases over 13 years in the second shelter and 27 cases over 5 years in the third shelter. Four cases of M gypseum dermatophytosis were treated in the third shelter. Young cats were most commonly infected and the disease was most commonly diagnosed in the fall and winter months. Lesions were inflammatory and found predominantly on the head and neck. There was a rapid response to treatment in all cases; mean (n = 20) and median (n = 17) days to mycological cure were calculated from available data. Fungal culture data revealed fomite carriage without clinical evidence of infection for Trichophyton species (n = 43) cats and M gypseum (n = 37) cats. CONCLUSIONS AND RELEVANCE: There is a paucity of clinical information about non-Microsporum canis dermatophytosis in shelter cats. This study data shows that Trichophyton species and M gypseum infections do occur but are uncommon. Based upon the rapid response to conventional treatment, these infections do not represent a treatment challenge, as most cats reached mycological cure within 3 weeks.

Evaluation of incubation time for Microsporum canis dermatophyte cultures.

Objectives The goal of this study was to determine how frequently Microsporum canis was isolated after 1, 2 and 3 weeks of incubation on dermatophyte culture medium either from untreated cats or cats during treatment. Methods This was an observational retrospective study. Toothbrush fungal culture results were examined from two data pools: untreated cats with suspect skin lesions and weekly fungal cultures from cats being treated for dermatophytosis. Results Results from 13,772 fungal cultures were reviewed and 2876 (20.9%) were positive for M canis. Of these, 2800 were confirmed as positive within 14 days of incubation and only 76 (2.6%) required >14 days for confirmation of M canis. In pretreatment specimens, 98.2% (1057/1076) of M canis isolates were recovered within 14 days of incubation in specimens from cats not known to have received prior antifungal treatment. For cats receiving treatment, 96.8% (1743/1800) of M canis isolates were recovered within 14 days of incubation. Of the 57 cultures that required >14 days for finalization, 21 required extra incubation time because cultures were grossly abnormal, 12 had concurrent contaminant growth delaying microscopic confirmation and 24 had no growth in the first 14 days. Of these 24, 19 had 1-2 colony-forming units (cfu)/plate and the remaining five plates had 5 to >10 cfu/plate, all with abnormal morphology. Conclusions and relevance The findings of this study show that it is not necessary to hold pretreatment or post-treatment fungal cultures for 21 days before finalizing cultures for no growth. Growth requiring >14 days had grossly abnormal morphology.