title: Epidemic and virulence characteristic of Shigella spp. with extended-spectrum cephalosporin resistance in Xiaoshan District, Hangzhou, China.
abstract: BACKGROUND
  Shigellae have become increasingly resistant to the extended-spectrum cephalosporin (ESC) worldwide and pose a great challenge to anti-infection treatment options. The purpose of this study was to determine the resistance, cephalosporin resistance mechanisms, virulence characteristic and genotype of ESC-resistant Shigella.
  
  
  METHODS
  From 2008 to 2012, Shigella isolates collected from diarrhea patients were detected for antibiotics sensitivity by disk diffusion, cephalosporin resistance determinants and virulence genes using polymerase chain reaction (PCR) and genotyping through enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR).
  
  
  RESULTS
  A total of 356 Shigella isolates were gathered, and 198 (55.6%, 58 S. flexneri and 140 S. sonnei) were resistant to ESC. All ESC-resistant isolates were susceptible to imipenem, and only 0.5% isolate was resistant to piperacillin/tazobactam. ESC-resistant S. flexneri showed high degrees of resistance to ampicillin (100%), ampicillin/sulbactam (96.6%), piperacillin (100%), trimethoprim/sulfamethoxazole (74.1%), ciprofloxacin (74.1%), levofloxacin (53.4%), ceftazidime (58.6%) and cefepime (58.6%). ESC-resistant S. sonnei exhibited high resistance rates to ampicillin (100%), piperacillin (100%) and trimethoprim/sulfamethoxazole (96.4%). Cephalosporin resistance genes were confirmed in 184 ESC-resistant isolates. bla(CTX-M) types (91.8%, mainly bla(CTX-M-14), bla(CTX-M-15) and bla(CTX-M-57)) were most prevalent, followed by bla(OXA-30) (26.3%). Over 99.0% ESC-resistant isolates harbored virulence genes ial, ipaH, virA and sen. However, set1 were more prevalent in ESC-resistant S. flexneri isolates than in S. sonnei isolates. ERIC-PCR results showed that 2 and 3 main genotypes were detected in ESC-resistant S. flexneri and S. sonnei, respectively.
  
  
  CONCLUSIONS
  Our findings indicated that a high prevalence of ESC-resistant Shigella mediated mainly by bla(CTX-M) with stronger resistance and virulence, and the existence of specific clones responsible for these Shigella infection in the region studied.
authors.forename: Chuan-Ling
authors.initials: CL
authors.lastname: Zhang
authors.affiliation: Department of Clinical Laboratory, Shanghai First People's Hospital, School of Medicine, Shanghai Jiaotong University, 100 Haining Road, Shanghai 200080, People's Republic of China. zzzz2000@tom.com.
authors.forename: Qing-Zhong
authors.initials: QZ
authors.lastname: Liu
authors.forename: Juan
authors.initials: J
authors.lastname: Wang
authors.forename: Xu
authors.initials: X
authors.lastname: Chu
authors.forename: Li-Meng
authors.initials: LM
authors.lastname: Shen
authors.forename: Yuan-Yu
authors.initials: YY
authors.lastname: Guo
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents; D000077723:Cefepime; D018550:Cephalosporin Resistance / Q000235:genetics*; D002511:Cephalosporins; D002648:Child; D002675:Child, Preschool; D002681:China; D002939:Ciprofloxacin; D004405:Dysentery, Bacillary / Q000382:microbiology*; D005260:Female; D019004:Galanin / Q000031:analogs & derivatives; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D010397:Penicillanic Acid / Q000031:analogs & derivatives; D010878:Piperacillin; D000077725:Piperacillin, Tazobactam Drug Combination; D016133:Polymerase Chain Reaction; D012760:Shigella / Q000235:genetics* / Q000472:pathogenicity; D013373:Substance P / Q000031:analogs & derivatives; D014774:Virulence; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; C074975:galantide; D000077725:Piperacillin, Tazobactam Drug Combination; D013373:Substance P; D002939:Ciprofloxacin; D000077723:Cefepime; D010397:Penicillanic Acid; D019004:Galanin; D001618:beta-Lactamases; D010878:Piperacillin