Penicillium spp

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Penicillium spp spores viewed under light microscopy

Penicillium spp are a keratinophilic hyphomycetes fungi which are a normal commensal of canine skin worldwide[1].

Coinfection with other dermatophytes such as Microsporum spp is very common[2].

Penicillium spp rarely cause disease but following skin damage, may proliferate within the dermis and cause ulcerative lesions.

Species which are pathogenic to dogs include:

  • Penicillium helicum - (sexual forms are denoted as Talaromyces helicus)
  • Penicillium marneffei[3]

Clinical signs of infection are rare, but disseminated opportunistic infections have been reported in dogs, with peripheral lymphadenopathy[4] and bronchopneumonia[5] predominating.

Diagnosis is based on culture of the fungus in a laboratory and visualization of hyphae in tissue samples. Fungal elements stained positively with Gomori methenamine silver and Periodic acid-Schiff stains. Definitive classification requires use of PCR assays[6].

Treatment would involve topical or parenteral antifungal chemotherapy with drugs such as amphotericin B, itraconazole, ketoconazole or turbinafine. Pulse treatment is recommended.

Disseminated Penicillium spp infections have a guarded prognosis due to the slow-growing nature of the fungus and parenteral treatments usually have to be extended for 4 -6 month period to effect clinical resolution..

References

  1. Efuntoye MO et al (2002) Fungi isolated from skins and pens of healthy animals in Nigeria. Mycopathologia 153(1):21-23
  2. Simpanya MF & Baxter M (1996) Isolation of fungi from the pelage of cats and dogs using the hairbrush technique. Mycopathologia 134(3):129-133
  3. Chaiwun B et al (2011) Investigation of dogs as a reservoir of Penicillium marneffei in northern Thailand. Int J Infect Dis 15(4):e236-e239
  4. Tomlinson JK et al (2011) Granulomatous lymphadenitis caused by Talaromyces helicus in a Labrador Retriever. Vet Clin Pathol 40(4):553-557
  5. Jones BG & Pollard RE (2012) Relationship between radiographic evidence of tracheobronchial lymph node enlargement and definitive or presumptive diagnosis. Vet Radiol Ultrasound 53(5):486-491
  6. Miyakawa K et al (2011) Pathology in practice. Penicilliosis. J Am Vet Med Assoc 238(1):51-53