Abstract
The carcass of a 0.301 kg male yellow-fronted Amazon (Amazona ochrocephala) was submitted for necropsy because the bird had died under “suspicious” circumstances. On gross postmortem examination, there was profound emaciation with marked pectoral muscle wasting. The prominent findings were in the coelomic cavity. There was displacement of the viscera to the right side from abnormal nodular to myxoid thickening over the serosal surface of the ventriculus. The liver was pale and mottled with necrotic margins, and merged with a caseous mass that was adherent to the ventriculus. Histopathology revealed marked inflammation in the ventriculus, extending transmurally from the submucosa through the layers of the muscularis, as well as focal extensive ulceration of the mucosa. This ulcer was coated with a necrosuppurative exudate in which were numerous and conspicuous yeast and bacterial colonies. Fungal elements were also identified in the liver and were associated with various degree of necrosis and inflammation. Histopathologically, fungal elements were consistent morphologically with Candida sp., presumed to be C. albicans. However, culture from tissue and from caseum yielded Candida krusei, which has not previously been reported as causing candidiasis in birds. Candida krusei was identified based on morphologic and biochemical features.2,11 Bacteriologic culture additionally revealed a heavy growth of E. coli, and Enterococcus sp., presumably secondary to septic coelomitis from the perforating ulcer.
Candida krusei is a pathogen of increasing concern in humans7,8 in which it causes invasive candidiasis.3,4,7,8 Controversy exists in medicine over the use of fluconazole in immunocompromised individuals with fungal disease, as it may predispose them to infection with the more aggressive, fluconazole-resistant C. krusei.3,4,7,8 There is strong evidence that biochemical properties of C. krusei result in poor to limited efficacy of fluconazole and some other azoles.1,5,9,12,13
Candida krusei has been documented sporadically in other animals.6,10 Infections with C. krusei in birds may be more common than this single case report suggests. Candidiasis in birds is often diagnosed through cytologic examination of specimens such as crop wash or fecal smears, and gastric candidiasis may also only be disclosed through histopathologic examination of formalin-fixed tissues. In either case, the yeast is usually assumed to be Candida albicans and rarely is cultured from specimens or tissues. This report suggests that speciation of the causative yeast may have substantial clinical significance, especially if systemic disease is suspected and fluconazole is being considered as a therapeutic option. In addition, Candida krusei infections in birds may constitute a more serious zoonotic threat to immunocompromised individuals than C. albicans.
Acknowledgments
We thank all the staff and volunteers at the Wildlife Care Center, Dr. Pisani of Micrim Labs, Inc. for yeast identification, Dr. D. Gamble of Antech Diagnostics and Dr. J. Paré for histopathology interpretation. Thanks to Dr. J. Paul-Murphy and Dr. B. Hartup for support of postgraduate study.
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