Diversity of Bipolaris species in clinical samples in the United States and their antifungal susceptibility profiles

Abstract

A set of 104 isolates from human clinical samples from the United States, morphologically compatible with Bipolaris, were morphologically and molecularly identified through the sequence analysis of the internal transcribed space (ITS) region of the nuclear ribosomal DNA (rDNA). The predominant species was Bipolaris spicifera (67.3%), followed by B. hawaiiensis (18.2%), B. cynodontis (8.6%), B. micropus (2.9%), B. australiensis (2%), and B. setariae (1%). Bipolaris cynodontis, B. micropus, and B. setariae represent new records from clinical samples. The most common anatomical sites where isolates were recovered were the nasal region (30.7%), skin (19.2%), lungs (14.4%), and eyes (12.5%). The antifungal susceptibilities of 5 species of Bipolaris to 9 drugs are provided. With the exception of fluconazole and flucytosine, the antifungals tested showed good activity.

Fig 1

Maximum likelihood tree inferred from ITS sequences of Bipolaris listed in Table S1 in the supplemental material. Branch lengths are proportional to the distance. Type or reference strains are shown in bold.

Fig 2

Conidia of Bipolaris species on OA at 25°C after 10 days. (A) B. spicifera, UTHSC 08-1706; (B) B. australiensis, UTHSC 09-406; (C) B. hawaiiensis, UTHSC 09-2906; (D) B. micropus, UTHSC 06-3896; (E) B. setariae, UTHSC05-3211; and (F) B. cynodontis, UTHSC 09-507. Scale bars, 10 μm.