Identification and antimicrobial susceptibility of clinical Nocardia species in a tertiary hospital in China

Abstract

Objectives: There is a lack of information on the activities of antimicrobial agents against Nocardia clinical isolates of specific species in China. The aim of this study was to determine the antibiotic susceptibility of 28 clinical isolates of Nocardia spp. isolated from Beijing Chao-Yang Hospital (Beijing, China).

Methods: Molecular diagnosis of Nocardia spp. was performed using partial 16S rRNA and rpoB gene sequences. Antimicrobial susceptibility testing was performed by broth microdilution according to Clinical and Laboratory Standards Institute (CLSI) recommendations.

Results: The species distribution was as follows: Nocardia cyriacigeorgica (n=13); Nocardia farcinica (n=6); Nocardia beijingensis (n=3); Nocardia abscessus (n=2); Nocardia wallacei (n=2); Nocardia otitidiscaviarum (n=1); and Nocardia nova (n=1). The susceptibility rates to trimethoprim/sulfamethoxazole (SXT), linezolid, amikacin, imipenem, tobramycin, ceftriaxone and cefotaxime were 100.0%, 100.0%, 92.9%, 75.0%, 67.9%, 67.9% and 64.3%, respectively, whilst the resistance rate both to ciprofloxacin and clarithromycin was 71.4%.

Conclusions: N. cyriacigeorgica was the most frequently isolated Nocardia spp. All clinical isolates showed low susceptibility to ciprofloxacin and clarithromycin and complete susceptibility both to SXT and linezolid, which can be considered the primary choice for the treatment of Nocardia infections in China.

Keywords: 16S Rrna; China; Drug pattern; Nocardia; Susceptibility; rpoB.