Genomic and Pathologic Findings for Prototheca cutis Infection in Cat

Invasive Fungal Infections and Oomycoses in Cats: 1. Diagnostic approach

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.

Intralesional amphotericin B in a cat with cutaneous protothecosis

A domestic cat was presented with nodular lesions on the nose/muzzle and pinnae. Protothecosis was diagnosed through cytological and histopathological examination, and culture. Molecular identification confirmed Prototheca wickerhamii infection. Intralesional application of amphotericin B in conjunction with oral terbinafine resulted in a significant reduction of the nasal lesion and complete resolution of the pinnal lesion, without adverse effects.

Protothecosis and Toxoplasma gondii co-infection in a dog from Nova Scotia, Canada

A 2-year-old, neutered male mixed-breed dog from Nova Scotia, Canada was evaluated for panuveitis, polyuria, polydipsia, and hind limb ataxia. Toxoplasmosis was diagnosed ante-mortem based on markedly increased Toxoplasma gondii titers. The post-mortem examination confirmed systemic toxoplasmosis and demonstrated disseminated protothecosis. This article documents the first reported case of canine protothecosis in Atlantic Canada. Key clinical message: This case report demonstrates that protothecosis should be a clinical consideration for dogs in Canada. Co-infection with other organisms may occur, which may mask clinical signs and potentially delay diagnosis.