Ann Lab Med 2017; 37(5): 415-419  
Characterization of Extended-Spectrum β-Lactamase Genes of Shigella flexneri Isolates With Fosfomycin Resistance From Patients in China
Yanyan Liu, M.D.1,2,*, Yue Cheng, M.D.1,*, Haifei Yang, M.D.1, Lifen Hu, M.D.1,2, Jun Cheng, M.D.1,2, Ying Ye, M.D.1,2, and Jiabin Li, M.D.1,2,3
Department of Infectious Diseases1, The First Affiliated Hospital of Anhui Medical University; Anhui Center for Surveillance of Bacterial Resistance2; Department of Infectious Diseases3, Chaohu Hospital of Anhui Medical University, Hefei, Anhui 230022, China
Correspondence to: Jiabin Li
Department of Infectious Diseases, The First Affiliated Hospital of Anhui Medical University, Jixi Road no. 218, Hefei 230022, China
Tel: +86-551-2922713 Fax: +86-551-2922281 E-mail:
Ying Ye
Department of Infectious Diseases, The First Affiliated Hospital of Anhui Medical University, Jixi Road no. 218, Hefei 230022, China
Tel: +86-551-2922713 Fax: +86-551-2922281 E-mail:
*These authors contributed equally to this work.
Received: January 7, 2016; Revised: January 18, 2017; Accepted: May 10, 2017; Published online: September 1, 2017.
© The Korean Society for Laboratory Medicine. All rights reserved.

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Background: The emergence of fosfomycin resistance and extended-spectrum β-lactamase (ESBL) genes is a serious threat to public health and a new challenge in shigellosis treatment. The purpose of this study was to identify fosfomycin resistance and characterize β-lactamase genes in fos-carrying isolates of Shigella flexneri from patients in China.
Methods: A total of 263 S. flexneri isolates were collected from 34 hospitals in the Anhui Province of China during September 2012-September 2015 and screened for fosA3, fosA, and fosC2 by PCR amplification and sequencing. The fos-carrying isolates were then screened for β-lactamase genes. The clonal relationships between fosA3-carrying isolates, the transmissibility of fosfomycin resistance, replicon types of plasmids carrying fosfomycin resistance genes and other associated resistance genes were investigated.
Results: Twenty-five of the 263 isolates (9.5%) showed resistance to fosfomycin, and 18 (6.8%) were positive for fosA3. None of the isolates was positive for fosA or fosC2. Seventeen of the isolates carrying fosA3 (94%) were CTX-M producers (seven CTX-M-55, five CTX-M-14, and five CTX-M-123), while three (16.7%) were TEM producers (TEM-1).Sixteen (88.9%) fosA3-carrying isolates exhibited multi-drug resistance. The replicon types of the 13 fosA3-carrying plasmids were IncF (n=13), IncHI2 (n=3), IncIl-Ir (n=2), and IncN (n=1).
Conclusions: Our results indicated that fosA3 could spread through plasmids in S. flexneri isolates, along with the blaCTX-M and blaTEM, which facilitate its quick dispersal. To the best of our knowledge, this is the first report of CTX-M-123-type ESBLs in S. flexneri isolates from patients in China.
Keywords: ESBLs, Plasmids, fosA3, Shigella flexneri, Replicon

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