Characterization of atypical Candida tropicalis and other uncommon clinical yeast isolates

Abstract

Clinical yeast isolates representing ot-glucoside-deficient variants of Candida tropicalis, C. lusitaniae, atypical C. albicans, and Saccharomyces cerevisiae were characterized. Additional physiological tests, including cellobiose fermentation, rhamnose assimilation, and triphenyl tetrazolium chloride reduction, are recommended for the detection and presumptive identification of uncommon Candida spp. in the clinical laboratory. Certain disease syndromes and associated

Disseminated candidiasis caused by a sucrose-negative variant of Candida tropicalis

“…2,3,5-Triphenyl-2Htetrazolium chloride was reduced to the red formazan compound. The proton magnetic resonance spectrum of the representative isolates was nearly identical with that of the atypical C. tropi(alis strain described by Ahearn et al 3and Schlitzer and Ahearn (20). Serological tests indicated a q~~~~ṽi /, C C. tropicalis-C. albicans serotype A grouping.…”

“…Of the 21 isolates, 16 were obtained from blood samples. Schlitzer and Ahearn (20) reaffirmed their classification of the yeast as an SN strain of C. tropicalis.…”

Occurrence of Clavispora lusitaniae, the teleomorph of Candida lusitaniae, among clinical isolates

“…One isolate, GSU A-1, grew well on enriched agar media and on yeast nitrogen base with glucose (Difco) but not at all on the API 20C clinical yeast system. Failure to grow on the defined medium in the API 20C system probably reflects a requirement for a purine or pyrimidine (17). Two isolates (CDC 89-026360 and CDC 90-006094) produced negligibleto-sparse pseudohyphae; all others had pseudohyphae of the candida-to-myocandida type on cornmeal agar.…”

“…Candida lusitaniae may be distinguished from the phenotypically similar and more common clinical isolate Candida * Corresponding author. tropicalis by failure of the latter to assimilate rhamnose and ferment cellobiose with detectable gas production and its positive assimilation of soluble starch (17). Furthermore, the G+C content of the DNA of Candida tropicalis (34.1 to 36.1 mol%) is distinct from that of Clavispora lusitaniae (43.4 to 46.3 mol%) (4).…”

Evaluation of the Baxter-MicroScan 4-hour enzyme-based yeast identification system

“…However, unlike C. parapsilosis, C. lusitaniae commonly demonstrates constitutive resistance to amphotericin B (6,17,19). Sucrose-negative variants of Candida tropicalis (designated C. tropicalis-SN or Candida paratropicalis) appear to exist only in human beings (1,22). Both C. tropicalis and its sucrose-negative variants have been associated with severe infections in immunosuppressed patients (1,26).…”