Isolation and identification of Kroppenstedtia eburnea isolates from multiple patient samples

Abstract

No clinical isolates have been reported for the recently described thermoactinomycete Kroppenstedtia eburnea. Between 2006 and 2011, we obtained 14 clinical isolates from patients in 9 U.S. states. Here we report growth characteristics, 16S rRNA gene sequencing, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry-based identification, and antimicrobial susceptibility profiles of this recently described organism.

Fig 1

Colony morphology on Columbia sheep blood agar (A) and microscopic Gram-stain morphology (original magnification, ×1,000) after subculturing in Mueller-Hinton broth (B).

Fig 2

(A) Phylogenetic tree based on partial 16S sequences of clinical and type strains of K. eburnea and related taxa. A clinical D. activa isolate was used for comparison; Aneurinibacillus thermoaerophilus and Bacillus fortis were used as outgroups. Percent bootstrap values are based on 1,000 iterations. (B and C) MALDI-TOF spectra and fingerprints (B) and principal component analysis-based clustering (C); clinical isolates of D. activa and Bacillus cereus were used for comparison. Intensity values are presented in arbitrary units; m/z, mass/charge ratio.