Abstract
BackgroundTo determine the prevalence, antimicrobial susceptibility patterns and related presence of mutations in quinolone resistance-determining region (QRDR) genes and plasmid-mediated quinolone resistance (PMQR) among Shigella flexneri isolates obtained from Jiangsu Province, China.MethodsA total of 400 Shigella flexneri clinical isolates collected during 2012–2015 were identified by biochemical and serological methods, and the antimicrobial susceptibility pattern was evaluated using the disc-diffusion method. PCR and DNA sequencing were accomplished to identify mutations in gyrA, gyrB, parC and parE, and the presence of qnrA, qnrB, qnrC, qnrD, qnrS, qepA and aac(6′)-Ib-cr genes were also detected.ResultsOf all the Shigella flexneri, 75.8% were resistant to nalidixic acid, and 37.0% were categorized as norfloxacin resistant. Overall, 75.5% of isolates possessed gyrA mutations (Ser83Leu, Asp87Gly/Asn and His211Tyr), while 84.3% had parC mutations (Ser80Ile, Ala81Pho, Gln91His and Ser129Pro). The most prevalent point mutations in gyrA and parC were Ser83Leu (75.5%, 302/400) and Ser80Ile (74.5%, 298/400), relatively. Besides, the Gln517Arg alternation in gyrB was detected in 13 S. flexneri isolates and no mutations were identified in parE. PMQR determinations of qnrB, qnrS and aac(6′)-Ib-cr were detected among 16 strains (4.0%).ConclusionsThe results presented here show that fluoroquinolone resistance in these clinical isolates result from mutations in chromosome, besides, despite the low prevalence of PMQR determinants in Jiangsu, it is essential to continue surveillance PMQR determinants in this area.
Highlights
To determine the prevalence, antimicrobial susceptibility patterns and related presence of mutations in quinolone resistance-determining region (QRDR) genes and plasmid-mediated quinolone resistance (PMQR) among Shigella flexneri isolates obtained from Jiangsu Province, China
Resistance rate of nalidixic acid fluctuated between 70.0% and 80.0% and no clear changing trend was observed
A retrospective study we conducted before have reported that 16 serotypes was observed between 2001 and 2011 in Jiangsu Province, with serovars 2a, 2b and 1a being the most common serotypes [7], in this study, we found that the top three most common S. flexneri serotypes were consistent with that years ago
Summary
Antimicrobial susceptibility patterns and related presence of mutations in quinolone resistance-determining region (QRDR) genes and plasmid-mediated quinolone resistance (PMQR) among Shigella flexneri isolates obtained from Jiangsu Province, China. Walker CL et al reported that China is among the 15 high-burden countries where nearly three-quarters of. Fluoroquinolones emerged as the preferred agents for treatment of Shigella infection, the progressive increase in antimicrobial resistance further narrows the choice of effective antimicrobials. Around China, an increase in the occurrence of antimicrobial resistance have been reported, resistance rate to norfloxacin was 22.3% in a surveillance between 2005 and. The proportion of norfloxacin-resistant S. flexneri was as high as 36.8% in the period 2006–2011 in Jiangsu Province [7]
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