Differential diagnosis in bloodstream infection with Trichosporon asahii and Geotrichum capitatum

Abstract:

ObjectiveTo provide reference for establishing diagnosis and differential diagnosis methods of rare yeastlike fungal bloodstream infection for clinical microbiology laboratory. MethodsTrichosporon asahii (T. asahii) and Geotrichum capitatum(G.capitatum) bloodstream infection was diagnosed and differentially diagnosed through clinical data analysis, morphological examination, biochemical reactions,and molecular biology technology.ResultsTwo types of yeastlike fungal bloodstream infections in case 1 and case 2 both occurred in leukemia agranulocytosis phase after chemotherapy, such infections were serious and highly similar. The cultivated colonies on blood agar plates of case 1 and case 2 were performed gram stain and microscopic examination. Hyphae, arthrospores and microconidia were visible in the former, thickness of hyphae branches and length of arthrospores were different, most presented rectangular and barrel shape; the latter can be seen hyphae with transparent septum broken up into arthrospores, presented rectangular shape, did not produce blastoconidia. Identification with API 20C AUX showed that they were T. asahii and G. capitatum. The PCR product sequences were compared with NCBI, suggesting that T. asahii  and G. capitatum were at sexual stage.  ConclusionComprehensive application of a variety of technical methods is helpful for improving the diagnosis accuracy of bloodstream infection with yeastlike fungi, identifying Trichosporon and Geotrichum to the species level may help physicians to understand such rare fungal infection, choose antifungal agents rationally, and improve clinical prognosis.［Key words］bloodstream infection; Trichosporon asahii; Geotrichum capitatum; yeastlike fungus; differential diagnosis