Phialemonium spp

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Phialemonium spp under light microscopy[1]

Phialemonium spp are an opportunistic fungal infection of dogs with immunocompromised states.

The dematiaceous or melanized fungi, once thought to possess low pathogenic potential, have become increasing causes of severe and disseminated infections in immunocompromised individuals. Phialemonium, considered to be a dematiaceous fungus by most authorities, although it lacks conspicuous dark pigmentation, was originally described as a genus intermediate between the Acremonium and Phialophora genera. They are normally considered a non-dermatophytic fungi in dogs that requires underlying dermatopathy to invade the skin[2]. The incidence of these infections is greater in warm and humid climate[3].

Both dermal and systemic phaeohyphomycosis due to granuloma formation have been reported[4].

Species which are pathogenic include:

  • Phialemonium curvatum
  • Phialemonium obovatum

Clinical signs of Phialemonium spp infections are often vague, but lameness due to bone infections[5], and respiratory symptoms are common due to pulmonary involvement.

Generalized pulmonary phaeohyphomycosis have been reported using radiographic and ultrasonographic studies[6].

Thick walled fungal hyphae are usually detected in impression smears from skin lesions. Staining with periodic acid-Schiff's stain is usually confirmatory.

Treatment with generalized phaeohyphomycosis usually requires aggressive treatment with amphotericin B, itraconazole, and ketoconazole, with curettage of the local area.

The prognosis for paecilomycosis is poor, although some treatment success has been reported.

References

  1. Black yeast.org
  2. Jand SK & Gupta MP (1989) Dermatomycosis in dogs. Mycoses 32(2):104-105
  3. Philpot CM & Berry AP (1984) The normal fungal flora of dogs. A preliminary report. Mycopathologia 87(3):155-157
  4. Smith AN et al (2000) Disseminated infection with Phialemonium obovatum in a German shepherd dog. J Am Vet Med Assoc 216(5):708-712, 684-685
  5. Lomax LG et al (1986) Osteolytic phaeohyphomycosis in a German shepherd dog caused by Phialemonium obovatum. J Clin Microbiol 23(5):987-991
  6. Sutton DA et al (2008) Pulmonary Phialemonium curvatum phaeohyphomycosis in a Standard Poodle dog. Med Mycol 46(4):355-359