Invasive fungal infections and oomycoses in cats: 1. Diagnostic approach

Abstract

Clinical relevance: In contrast to superficial fungal infections, such as dermatophytosis, invasive fungal infections (IFIs) are characterised by penetration of tissues by fungal elements. Disease can spread locally within a region or can disseminate haematogenously or via the lymphatics. The environment is the most common reservoir of infection. Since fungal spores are airborne, indoor cats are also susceptible to IFIs. Some environmental fungi are ubiquitous and present globally, while others are endemic or hyperendemic within specific geographic regions. Zoonotic pathogens include Microsporum canis, Sporothrix schenckii and Sporothrix brasiliensis. Aim: In the first of a two-part article series, the approach to the investigation of feline IFIs and oomycoses is reviewed. As well as tips for diagnosis, and information on the ecological niche and distribution of fungal pathogens, the review covers clinical presentation of the most common IFIs, including cryptococcosis, histoplasmosis, blastomycosis, coccidioidomycosis, sporotrichosis, phaeohyphomycosis, aspergillosis and dermatophytic pseudomycetoma, as well as the oomycoses pythiosis, lagenidiosis and paralagenidiosis. In Part 2, the spectrum of activity, mechanisms of action, pharmacokinetic and pharmacodynamic properties and adverse effects of antifungal drugs are reviewed, and the treatment and prognosis for specific IFIs and oomycoses are discussed. Evidence base: The review draws on published evidence and the authors' combined expertise in feline medicine, mycology, dermatology, clinical pathology and anatomical pathology.

Case report: Dermatophytic pseudomycetoma in a domestic Korean short hair cat treated with intralesional injection of amphotericin B and oral terbinafine administration

“…DPM has been rarely reported in domestic Short Hair Cats. Most cases of DPM have been reported in Persian cats which are predisposed to dermatophytosis and occasional cases of DPM ( 3 , 5 ). In Persian cats, DPM can be formed through direct invasion of the dermatophytes to dermal tissues via inadvertent rupture of follicular structures ( 3 , 5 ).…”

“…Most cases of DPM have been reported in Persian cats which are predisposed to dermatophytosis and occasional cases of DPM ( 3 , 5 ). In Persian cats, DPM can be formed through direct invasion of the dermatophytes to dermal tissues via inadvertent rupture of follicular structures ( 3 , 5 ). Interestingly, in this case, although 13 cats were living together, clinical signs were only seen in this patient.…”

“…Feline dermatophytic pseudomycetoma (DPM) comprises uncommon, deep dermal and sub-cutaneous fungal infections caused by dermatophytes, mostly Microsporum canis ( 1 , 2 ). The majority of DPM infections have been described in Persian cats, suggesting a genetically programmed selective immunodeficiency ( 3 ). Clinical manifestations of DPM include nodular swelling, ulceration, draining sinuses, and grains in tissue that are micro-aggregates of the causative organism.…”

Invasive fungal infections and oomycoses in cats 2. Antifungal therapy

“…For invasive fungal infections (IFIs) and oomycoses (hereafter termed invasive fungal-like infections [IFLIs]) in cats, antifungal susceptibility testing should be performed when possible, as outlined in Part 1. 1 Targeted antifungal therapy based on the susceptibility profile of the pathogen isolated is an important factor in determining treatment success.…”

“…Given that >100 species of pigmented fungi cause phaeohyphomycosis in humans and animals, antifungal susceptibility testing is recommended to guide therapy. If this is not possible, molecular identification of the infecting agent can usually be achieved by panfun-gal PCR of formalin-fixed biopsy tissues (see Part 1 1 ). This can help inform the best empirical therapy since antifungal susceptibility profiles vary between different fungal genera and species.…”