Distribution of the optrA gene in Enterococcus isolates at a tertiary care hospital in China. (June 2019)

• Record Type: Journal Article
• Authors: Zhou, Wanqing; Gao, Shuo; Xu, Hongjing; Zhang, Zhifeng; Chen, Fei; Shen, Han; Zhang, Chunni
• Is Part Of: Journal of global antimicrobial resistance. Volume 17(2019)
• Page Start: 180
• Page End: 186
• Publication Date: 2019-06
• Subjects: Linezolid -- Non-susceptible -- Enterococcus -- Resistance -- OptrA -- Cfr gene -- WGS; Drug resistance -- Periodicals; Drug resistance -- Periodicals; Drug resistance; Periodicals; 616.9041
• DOI: 10.1016/j.jgar.2019.01.001
• Languages: English
• ISSNs: 2213-7165

Abstract

Highlights: 27 linezolid-non-susceptible- Enterococcus were identified at a tertiary care hospital of China. OptrA was the main gene mediating LNSE in 23 isolates, with ST16 E. faecalis clonal dissemination. PCR-based sequencing and WGS revealed 7 optrA variants in 16 isolates. OptrA was found downstream of fexA by searching pE349 sequence on WGS data. This is the first report on the prevalence of LNSE and the optrA gene in Nanjing, China. Abstract: Objectives: Linezolid-resistant Enterococcus have spread worldwide. This study investigated the prevalence of linezolid-non-susceptible Enterococcus (LNSE) and the potential mechanism and molecular epidemiology of LNSE isolates from Nanjing, China. Methods: Linezolid susceptibility of 2555 Enterococcus was retrospectively determined by Etest. Vancomycin and teicoplanin MICs were determined for LNSE by Etest. PCR and DNA sequencing were used to investigate the potential molecular mechanism. Clonal relatedness between LNSE isolates was analysed by MLST. WGS was also performed. Results: A total of 27 Enterococcus isolates (24 Enterococcus faecalis, 3 Enterococcus faecium ) with linezolid MICs of 4–48 μg/mL were identified, among which 20 E. faecalis and 3 E. faecium were positive for optrA . No mutations were found in genes encoding domain V of 23S rRNA or ribosomal proteins L3/L4; the cfr gene was not found. The 24 linezolid-non-susceptible E. faecalis were classified into eight STs (ST16, ST480, ST476, ST631, ST585, ST428, ST25 and ST689). The three linezolid-non-susceptible E. faecium were classified as ST17, ST400 and ST195. Comparison of the deduced OptrA amino acid sequences of the 23 optrA -positive isolates by PCR-based sequencing and WGS with that of the original OptrA from E. faecalis E349 revealed seven variants (KD, EDP, EDM, D, EDD, RDK and DP) in 16 isolates, with no mutations in the remaining 7 isolates. optrA was found downstream of fexA by searching the pE349 sequence based on WGS data. Conclusions: Emergence of LNSE with optrA -mediated resistance and clonal dissemination of ST16 E. faecalis in our hospital may pose a potential public-health threat.