PLoS ONE (Jan 2015)

Antimicrobial Resistance of Shigella flexneri Serotype 1b Isolates in China.

  • Xianyan Cui,
  • Chaojie Yang,
  • Jian Wang,
  • Beibei Liang,
  • Shengjie Yi,
  • Hao Li,
  • Hongbo Liu,
  • Peng Li,
  • Zhihao Wu,
  • Jing Xie,
  • Leili Jia,
  • Rongzhang Hao,
  • Ligui Wang,
  • Yuejin Hua,
  • Shaofu Qiu,
  • Hongbin Song

DOI
https://doi.org/10.1371/journal.pone.0129009
Journal volume & issue
Vol. 10, no. 6
p. e0129009

Abstract

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Shigella flexneri serotype 1b is among the most prominent serotypes in developing countries, followed by serotype 2a. However, only limited data is available on the global phenotypic and genotypic characteristics of S. flexneri 1b. In the present study, 40 S. flexneri 1b isolates from different regions of China were confirmed by serotyping and biochemical characterization. Antimicrobial susceptibility testing showed that 85% of these isolates were multidrug-resistant strains and antibiotic susceptibility profiles varied between geographical locations. Strains from Yunnan were far more resistant than those from Xinjiang, while only one strain from Shanghai was resistant to ceftazidime and aztreonam. Fifteen cephalosporin resistant isolates were identified in this study. ESBL genes (blaSHV, blaTEM, blaOXA, and blaCTX-M) and ampC genes (blaMOX, blaFOX, blaMIR(ACT-1), blaDHA, blaCIT and blaACC) were subsequently detected among the 15 isolates. The results showed that these strains were positive only for blaTEM, blaOXA, blaCTX-M, intI1, and intI2. Furthermore, pulsed-field gel electrophoresis (PFGE) analysis showed that the 40 isolates formed different profiles, and the PFGE patterns of Xinjiang isolates were distinct from Yunnan and Shanghai isolates by one obvious, large, missing band. In summary, similarities in resistance patterns were observed in strains with the same PFGE pattern. Overall, the results supported the need for more prudent selection and use of antibiotics in China. We suggest that antibiotic susceptibility testing should be performed at the start of an outbreak, and antibiotic use should be restricted to severe Shigella cases, based on resistance pattern variations observed in different regions. The data obtained in the current study might help to develop a strategy for the treatment of infections caused by S. flexneri 1b in China.