title: Molecular characteristics of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae causing intra-abdominal infections from 9 tertiary hospitals in China.
abstract: BACKGROUND
  Recently, the emergence of multidrug-resistant organisms such as extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae has raised considerable concern regarding the appropriate treatment of intra-abdominal infections (IAIs). In this study, we investigated the molecular characteristics of ESBL among clinical isolates of Escherichia coli and Klebsiella pneumoniae causing IAIs and their pattern of antimicrobial resistance, which can provide useful information about the epidemiology and risk factors associated with these infections.
  
  
  METHODS
  One hundred sixty-seven E.coli and 47 K. pneumoniae ESBL-producing strains causing IAIs were collected from 9 hospitals in China, during 2012 and 2013. The antimicrobial susceptibility profile of these strains was determined. Polymerase chain reaction and sequencing were performed to identify genes for β-lactamase (blaTEM, blaSHV, blaOXA-1-like, and blaCTX-M). The isolates were also analyzed by pulsed-field gel electrophoresis (PFGE).
  
  
  RESULTS
  In 167 ESBL-producing E. coli strains, 104 strains (62.3%) were positive for CTX-M, and 9 strains (5.39%) were positive for SHV. Among the 47 K. pneumoniae strains, 35 strains (74.5%) were positive for SHV-2a, 12 strains (25.5%) were positive for CTX-M. No TEM-type and OXA-1-like strain was detected among all the ESBL-producing strains. Regarding the CTX-M-positive E. coli and K. pneumoniae strains, CTX-M-15 was the most common genotype in E. coli and K. pneumoniae strains, accounting for 28.7% and 17.0%, respectively, followed by CTX-M-55 accounting for 16.2% and 2.13%, respectively; the remaining genotypes included CTX-M-123 and CTX-M-82. PFGE showed that E.coli and K. pneumoniae ESBL-producing strains causing IAIs were diverse and that emerging resistance may not be due to the dissemination of national clones.
  
  
  CONCLUSIONS
  The present study revealed that in ESBL-producing strains causing IAIs in China, the most common genotype for E.coli was CTX-M-15 and for K. pneumoniae was SHV-2a. However, there was a wide diversity of strains causing IAIs among the ESBL-producing E. coli and K. pneumoniae.
authors: Department of Laboratory Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China.
authors: Kang
authors: K
authors: Liao
authors: Department of Laboratory Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China.
authors: Yili
authors: Y
authors: Chen
authors: Department of Laboratory Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China.
authors: Menghe
authors: M
authors: Wang
authors: Department of Laboratory Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China.
authors: Penghao
authors: P
authors: Guo
authors: Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing 100730, China.
authors: Qiwen
authors: Q
authors: Yang
authors: Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200025, China.
authors: Yuxing
authors: Y
authors: Ni
authors: SirRunRun Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China.
authors: Yunsong
authors: Y
authors: Yu
authors: Zhong Shan Hospital of Fu Dan University, Shanghai 200032, China.
authors: Bijie
authors: B
authors: Hu
authors: Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors: Ziyong
authors: Z
authors: Sun
authors: First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China.
authors: Wenxiang
authors: W
authors: Huang
authors: Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China.
authors: Yong
authors: Y
authors: Wang
authors: Xiangya Hospital, Central Southern University, Changsha 410008, China.
authors: Anhua
authors: A
authors: Wu
authors: First Affiliated Hospital of Zhengzhou University, Zhenzhou 450052, China.
authors: Xianju
authors: X
authors: Feng
authors: The General Hospital of People's Liberation Army, Beijing 100853, China.
authors: Yanping
authors: Y
authors: Luo
authors: General Hospital of Tianjin Medical University, Tianjing 300052, China.
authors: Zhidong
authors: Z
authors: Hu
authors: First Affiliated Hospital of Chinese Medical University, Shenyang 110001, China.
authors: Yunzhuo
authors: Y
authors: Chu
authors: First Affiliated Hospital of Haerbin Medical College, Haerbin 150081, China.
authors: Shulan
authors: S
authors: Chen
authors: Chaoyang Hospital of Capital Medical College, Beijing 100020, China.
authors: Bin
authors: B
authors: Cao
authors: Friendship Hospital of Capital Medical College, Beijing 100020, China.
authors: Jianrong
authors: J
authors: Su
authors: Second Affiliated Hospital of Nanchang University, Nanchang 330006, China.
authors: Bingdong
authors: B
authors: Gui
authors: People's Hospital of Jilin Province, Jilin 130021, China.
authors: Qiong
authors: Q
authors: Duan
authors: People's Hospital of Haikou City, Haikou 570208, China.
authors: Shufang
authors: S
authors: Zhang
authors: General Hospital of Nanjing Military Command, Nanjing 210002, China.
authors: Haifeng
authors: H
authors: Shao
authors: First Affiliated Hospital of Zhejiang University, Hangzhou 310003, China.
authors: Haishen
authors: H
authors: Kong
authors: Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing 100730, China. Electronic address: xuyingchunbm@163.com.
authors: Yingchun
authors: Y
authors: Xu
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002681:China; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D014644:Genetic Variation; D006801:Humans; D059413:Intraabdominal Infections / Q000382:microbiology*; D007710:Klebsiella Infections / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D058889:Molecular Typing; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D062606:Tertiary Care Centers; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001618:beta-Lactamases
keywords: ESBL; Intra-abdominal infections; Molecular characteristics