Submitted to: Journal of Clinical Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/28/2007
Publication Date: 2/1/2008
Citation: Bishop, J.A., Chase, N., Magill, S.S., Kurtzman, C.P., Fiandaca, M.J., Merz, W.G. 2008. Candida bracarensis Detected Among Isolates of Candida glabrata by Petide Nucleic Acid Fluorescence in Situ Hybirdization: Susceptibility Data and Documentation of Presumed Infection. Journal of Clinical Microbiology. 46(2):443-446. Interpretive Summary: Accurate identification of clinically important yeasts is often difficult using the standard growth tests employed in medical diagnostic laboratories. Gene sequence analysis based on research at the National Center for Agricultural Utilization Research is increasingly being used by clinical laboratories to accurately identify disease causing yeasts. In this study, Candida bracarensis was discovered among clinical isolates from Johns Hopkins University Hospital. This is the first recognition of this pathogenic yeast in the U.S. and was possible only because the identification was made using DNA sequences. Because of differences in antibiotic sensitivity among clinical yeast species, accurate identification is essential for effective treatment. This cooperative research with Johns Hopkins University will provide needed information to effectively treat patients with yeast infections.
Technical Abstract: Molecular taxonomic studies have revealed new yeast (Candida) species among phenotypically-delineated species: the best example being Candida dubliniensis. This study was designed to determine the occurrence of two new molecularly-defined species, Candida bracarensis and Candida nivariensis, which are closely related to and identified as Candida glabrata by phenotypic assays. A total of 137 recent clinical isolates of C. glabrata identified by phenotypic characteristics was tested with C. bracarensis and C. nivariensis species-specific PNA FISH probes. Three of 137 (2.2 %) isolates were positive with the C. bracarensis probe, whereas the control strain, but none of the clinical isolates was positive with the C. nivariensis probe. D1/D2 sequencing confirmed the identification of the three isolates as C. bracarensis. Clinically, one C. bracarensis isolate was recovered from a presumed infection, a polymicrobial pelvic abscess infection in a patient with perforated diverticulitis. The other two were recovered from two adult oncology patients who were only colonized. C. bracarensis was white on CHROMagar Candida, had variable API 20 C patterns that overlapped with C. nivariensis and some C. glabrata isolates, and had variable results with a rapid trehalose assay. Interestingly, an isolate from one of the colonized oncology patients was resistant in vitro to fluconazole (FLC), itraconazole (ITC), voriconazole (VRC), and posaconazole (PSC). In summary, C. bracarensis was detected among clinical isolates of C. glabrata while C. nivariensis was not. One C. bracarensis isolate was recovered causing a presumed deep infection, and another isolate was azole-resistant. Whether clinical laboratories should identify C. bracarensis will require more data.