Prevalence and antimicrobial resistance of Shigella flexneri serotype 2 variant in China

Abstract

Shigella flexneri serotype 2 variant (II:3,4,7,8) was isolated in 2008 and first reported in China in 2013. In the present study, epidemiological surveillance from 2003 to 2013 in China suggested that this serotype first appeared in Guangxi in 2003; it then emerged in Shanghai and Xinjiang in 2004 and in Henan in 2008. Of the 1813 S. flexneri isolates, 58 S. flexneri serotype 2 variant strains were identified. Serotype 2 variant has emerged as a prominent serotype in recent years, with 2a (32.6%), X variant (25.2%), 1a (9.4%), X (6.3%), 2b (5.4%), and 1b (3.6%). According to phenotypic and genotypic analysis, the serotype 2 variant originated from 2a to 2b. A higher antibiotic resistance rate was observed between 2009 and 2013 than that between 2003 and 2008. Among 22 cephalosporin-resistant isolates, blaTEM-1, blaOXA-1, blaCTX-3, blaCTX-14, and blaCTX-79 were detected. Among 22 fluoroquinolone-resistant isolates, a Ser80Ile mutation in parC was present in all of the isolates. Moreover, 21 isolates had three gyrA point mutations (Ser83Leu, His211Tyr, Asp87Asn, or Gly) and one isolate had two gyrA point mutations (Ser83Leu and His211Tyr). The prevalence of His211Tyr in the fluoroquinolone-resistant isolates is concerning, and the mutation was first reported in China. Besides, 22 isolates harbored the aac(6′)-Ib-cr gene, and two isolates harbored qnrS1. In view of the increased epidemic frequency and multidrug-resistant strain emergence, continuous surveillance will be needed to understand the actual disease burden and provide guidance for shigellosis.

Antimicrobial Resistance of Salmonella enterica Serovar Typhimurium in Shanghai, China

“…All the cephalosporin-resistant isolates were analyzed using PCR assays for the presence of extended-spectrum β-lactamase (ESBL) genes such as bla CTX-M groups, bla OXA , bla TEM , bla SHV , and bla CMY (Hasman et al, 2005; Weill et al, 2006; Cui et al, 2015). PCR amplification of quinolone resistance-determining regions (QRDRs) of gyrA, gyrB, parC , and parE (Giraud et al, 1999) and plasmid-mediated quinolone resistance (PMQR) determinants [ qnrA, qnrB, qnrD, qnrS , and aac(6′)-Ib-cr ] (Park et al, 2006; Cui et al, 2015) were performed on the ciprofloxacin-resistant or intermediate resistant isolates.…”

“…PCR amplification of quinolone resistance-determining regions (QRDRs) of gyrA, gyrB, parC , and parE (Giraud et al, 1999) and plasmid-mediated quinolone resistance (PMQR) determinants [ qnrA, qnrB, qnrD, qnrS , and aac(6′)-Ib-cr ] (Park et al, 2006; Cui et al, 2015) were performed on the ciprofloxacin-resistant or intermediate resistant isolates. All azithromycin-resistant isolates were subjected to PCR to detect macrolide-resistance genes including mphA, mphB, ermA, ermB, ereA, mefA , and msrA (Phuc Nguyen et al, 2009).…”

Update on:Shigellanew serogroups/serotypes and their antimicrobial resistance

“…Epidemiological surveillance from 2003 to 2013 in China suggested that the variants of S. flexneri serotypes have emerged as a prominent serotype in recent years, with 2a (32Á6%), X variant (25Á2%), 1a (9Á4%), X (6Á3%), 2b (5Á4%) and 1b (3Á6%) (Cui et al 2015).…”

Epidemic and molecular characterization of fluoroquinolone-resistant Shigella dysenteriae 1 isolates from calves with diarrhea

“…To understand the underlying mechanism of uoroquinolone resistance, four quinolone resistancedetermining region (QRDR) genes, DNA gyrase (gyrA and gyrB) and topoisomerase IV (parC and parE), and six plasmid-mediated quinolone resistance (PMQR) determinant genes, qnrA, qnrB, qnrD, qnrS, aac(6')-Ib-cr and qepA, were ampli ed for uoroquinolone-resistant isolates in our study. 4,18,19 The obtained PCR fragments were sequenced after puri cation and analyzed through comparison with sequences in GenBank. The primer information is listed in Table S2.…”