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Among diseases of horses caused by fungi (=mycoses), dermatophytosis, cryptococcosis and aspergillosis are of particular concern, due their worldwide diffusion and, for some of them, zoonotic potential. Conversely, other mycoses such as subcutaneous (i.e., pythiosis and mycetoma) or deep mycoses (i.e., blastomycosis and coccidioidomycosis) are rare, and/or limited to restricted geographical areas. Generally, subcutaneous and deep mycoses are chronic and progressive diseases; clinical signs include extensive, painful lesions (not pathognomonic), which resemble to other microbial infections. In all cases, early diagnosis is crucial in order to achieve a favorable prognosis. Knowledge of the epidemiology, clinical signs, and diagnosis of fungal diseases is essential for the establishment of effective therapeutic strategies. This article reviews the clinical manifestations, diagnosis and therapeutic protocols of equine fungal infections as a support to early diagnosis and application of targeted therapeutic and control strategies., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Yeasts of the genus Malassezia are commensals of the normal skin microbial flora of humans and animals. These yeasts may become pathogenic under certain circumstances and their pathogenic role may be related to host immune system as well to yeast virulence factors (e.g., phospholipase production and biofilm formation). This study aims to evaluate the in vitro ability of M. pachydermatis strains to produce biofilm, and its relationship with phospholipase activity and the genetic make-up of isolates from lesioned (n=32) and healthy (n=30) dog skin. The production of biofilm was determined by crystal violet staining and scanning electronic microscopy (SEM). Biofilm was produced by almost all M. pachydermatis isolates (95.2%) from dogs with and without skin lesions at variable level and different structure. At the SEM, biofilm matrix presented adhering blastoconidia clustered in multi- or monolayer structures with variable quantity of extracellular production. Of the three genotypes detected, genotype B showed the lowest ability to produce biofilm. Of the 59 isolates producing biofilm, 33 (55.9%) produced phospholipase, with a higher biofilm formation (p<0.05) in strains collected from animals with skin lesions. It is here suggested that phospholipase production might act in synergism with the biofilm formation by inducing or exacerbating skin lesions in dogs. The results provide evidences for a better understanding of the interactions between yeasts and host immune system, toward revealing the pathogenicity of M. pachydermatis in animals., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The microdilution antifungal method (CLSI BMD, M27-A3) was used for testing the antifungal susceptibility of Malassezia species. However, optimal broth media that allow sufficient growth of M. pachydermatitis and produce reliable and reproducible MICs using the CLSI BMD protocol are yet to be established. In this study, the susceptibility of M. pachydermatis isolates to ketoconazole (KTZ), itraconazole (ITZ) and fluconazole (FLZ) was evaluated in vitro by the CLSI BMD test using Christensen's urea broth (CUB) and mRPMI 1640 containing lipid supplementation, Sabouraud dextrose broth with 1% tween 80 (SDB), and Dixon broth (DXB). A FLZ-resistant M. pachydermatis was generated in vitro and tested under the same conditions. A good growth of M. pachydermatis incubated for 48 and 72 h, respectively, was observed in CUB, SDB and DXB and not in mRPMI 1640 (p<0.001). No statistically significant differences were detected between the MIC values registered after 48 h and 72 h incubation. ITZ displayed lower MIC values than KTZ and FLZ regardless of the media employed. A large number of FLZ-resistant Malassezia strains (86.6%) was observed using DXB. A MIC>64 mg/L was observed only when the FLZ-resistant M. pachydermatis isolate was tested in SDB. Based on the results obtained herein, culture in SDB, stock inoculum suspensions of 1-5 × 10(6)CFU/ml, and an incubation time of 48 h are proposed as optimal conditions for the evaluation of the in vitro antifungal susceptibility of M. pachydermatis using a modified CLSI BMD protocol., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Canine Malassezia dermatitis is frequently treated with systemic ketoconazole (KTZ) and itraconazole (ITZ). However, no information is available on the antifungal susceptibility to azoles and allilamine of Malassezia pachydermatis isolates from dogs with or without skin lesions. The present study was designed to evaluate the in vitro antifungal susceptibility of M. pachydermatis strains from dogs with or without skin lesions to KTZ, ITZ, miconazole (MICO), fluconazole (FLZ), posaconazole (POS), voriconazole (VOR) and terbinafine (TER) using the Clinical and Laboratory Standards Institute reference Broth Microdilution Method (CLSI M27-A2). The association between the susceptibility to antifungal compounds and the origin of M. pachydermatis, from skin with or without lesions has been also assessed. A total of 62 M. pachydermatis strains from healthy dogs (i.e., Group A=30) or with skin lesions (i.e., Group B=32) were tested. ITZ, KTZ and POS showed the highest activity against M. pachydermatis strains, whereas MICO TER and FLZ the lowest. A higher number of Malassezia resistant strains were registered among isolates from Group B than those from Group A. This study indicates that M. pachydermatis strains were susceptible to ITZ, KTZ, and POS. However, dogs with lesions may harbour strains with low susceptibility to antifungal agents and displaying cross-resistance phenomena to azole. The antifungal therapy in Malassezia infections requires careful appraisal of choice of drugs especially in cases of unresponsiveness to antifungal treatment or recurrent infections., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Little information is available on the molecular epidemiology of dermatophytoses in rabbit farms and farm workers. A total of 117 isolates belonging to the Trichophyton mentagrophytes complex and 21 isolates of Microsporum canis were collected from rabbits with or without skin lesions, air samples of farms known to harbour these pathogens, and from farm workers with skin lesions, and molecularly characterized. Sequencing of amplicons from the T. mentagrophytes complex and M. canis isolates revealed the presence of one sequence-type for both partial chitin synthase-1 gene (pchs-1) and ribosomal internal transcribed spacer (ITS+), respectively. On the basis of comparative sequence analyses, isolated representing the T. mentagrophytes complex were molecularly identified as Trichophyton interdigitale (zoophilic) Priestley. The M. canis and T. interdigitale pchs-1 sequences herein analysed were 100% homologous to known sequences from different hosts (i.e., cats, dogs, humans and rabbits). Conversely, the ITS+ sequences of T. interdigitale from dogs, pigs and mice were identical, but displayed up to 8.6% difference with those from humans, guinea pigs and rabbits. The results of this study suggest that environmental and clinical isolates of T. interdigitale (zoophilic) and M. canis might share a common origin. Interestingly, the close phylogenetic relationship between T. interdigitale (zoophilic) strains and isolates from dogs, pigs and mice might indicate that these animals represented a reservoir of dermatophyte infection in rabbit farms. These animal species should therefore be considered when setting up control protocols to prevent infections by dermatophytes and their zoonotic transmission., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Fungi of the genus Geotrichum are commonly found in the environment and, in some circumstances, they may cause diseases in humans and animals. Although these fungi have been isolated from skin lesions of some animal species, their pathogenic role in horses remains uncertain. With the aim to investigate the role of Geotrichum candidum as etiological agent of dermatomycoses, a retrospective study of 64 horses presenting skin lesions and suspected to have fungal infections was carried out. For each animal, anamnestic data were recorded and fungal culture were performed using hair. Out of 64 cases, 18 (28.1%) were positive for G. candidum and only two (3.1%) for dermatophytes (i.e., one for Microsporum equinum and the other for Microsporum canis). Alopecia, desquamation, and pruritus localized mainly on head and neck were frequently observed in G. candidum infected animals. Most of G. candidum infections were recorded during spring (44.4%). Out of the 18 animals presenting G. candidum infections, eight were treated using a disinfectant with antifungal properties. After one month of treatment, the clinical lesions were healed and fungal cultures resulted negative. The high prevalence of G. candidum in skin lesions of horses and the clinical recover following antifungal treatment indicated that these yeast-like fungi might play a role as etiological agents of horse cutaneous mycoses., (Copyright © 2010 Elsevier B.V. All rights reserved.)