Molecular characterization of the extended-spectrum beta-lactamase (ESBL)-producing Shigella spp. in Shanghai

Eur J Clin Microbiol Infect Dis. 2015 Mar;34(3):447-51. doi: 10.1007/s10096-014-2244-2. Epub 2014 Sep 25.

Abstract

Shigellosis is a public health concern in China. We tested 216 Shigella isolates collected in Shanghai in 2007 for the production of extended-spectrum beta-lactamases (ESBLs). ESBL-producing isolates were characterized using polymerase chain reaction (PCR)-based genotyping, conjugation, pulsed-field gel electrophoresis (PFGE), and DNA sequence analysis of regions adjacent to bla genes. Plasmids containing genes encoding ESBLs were analyzed using plasmid replicon typing. ESBLs were produced by 18.1 % (39/216) of Shigella isolates, and all 39 ESBL-producing strains harbored bla CTX-M genes. CTX-M-14 was the most frequent variant (69.2 %, 27/39), followed by CTX-M-15 (15.4 %, 6/39). All bla CTX-M genes were transferable by conjugation, and the insertion sequence ISEcp1 was detected upstream of all bla CTX-M genes. The CTX-M-producing Shigella isolates showed high clonal diversity. IncI1, IncFII, IncN, and IncB/O replicons were respectively detected in 23 (58.9 %), 9 (23.1 %), 1 (2.6 %), and 1 (2.6 %) of the 39 transconjugants carrying bla CTX-M. The bla CTX-M-14 genes were most frequently carried by IncI1 (n = 13, 48.1 %) or IncFII (n = 9, 33.3 %) plasmids, and the bla CTX-M-15 genes were closely associated with IncI1 (n = 5, 83.3 %). Our findings demonstrate the high prevalence of ESBL-producing Shigella in Shanghai, the importance of plasmids and ISEcp1 as carriers of bla CTX-M genes, and the close association between certain bla CTX-M genes with a specific plasmid.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • China / epidemiology
  • Cluster Analysis
  • Conjugation, Genetic
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • Dysentery, Bacillary / epidemiology*
  • Dysentery, Bacillary / microbiology*
  • Electrophoresis, Gel, Pulsed-Field
  • Genotype
  • Humans
  • Molecular Typing
  • Plasmids / analysis
  • Polymerase Chain Reaction
  • Prevalence
  • Sequence Analysis, DNA
  • Shigella / classification
  • Shigella / enzymology*
  • Shigella / genetics*
  • Shigella / isolation & purification
  • beta-Lactamases / genetics*
  • beta-Lactamases / metabolism

Substances

  • DNA, Bacterial
  • beta-Lactamases