CTX-M-15-D-ST648 escherichia coli from companion animals and horses: Another pandemic clone combining multiresistance and extraintestinal virulence?

Christa Ewers, Astrid Bethe, Ivonne Stamm, Mirjam Grobbel, Peter A. Kopp, Beatriz Guerra, Michael Stubbe, Yohei Doi, Zhiyong Zong, Axel Kola, Katharina Schaufler, Torsten Semmler, Angelika Fruth, Lothar H. Wieler, Sebastian Guenther

Research output: Contribution to journalArticlepeer-review

127 Citations (Scopus)


Objectives: To discern the relevance of ST648 extended-spectrum β-lactamase (ESBL)-producing Escherichia coli as a putative new group of multiresistant and extraintestinal pathogenic strains in animals, its frequency, ESBL types, antimicrobial resistance patterns and virulence gene (VG) profiles should be determined and compared with ST131 strains from the same collection of strains. Methods: ESBL-producing E. coli isolates (n=1152), consecutively sampled from predominantly dogs, cats and horses between 2008 and 2011, were assigned to a phylogenetic group by PCR. Partial multilocus sequence typingwas performed for group D and B2 strains and strains presumed to be D-ST648 and B2-ST131 were fully typed. ESBL genes and extraintestinal pathogenic E. coli (ExPEC)-like VGs were characterized by PCR and sequence analysis and antimicrobial resistance was determined by broth dilution. Clonal analysis was done by PFGE. Results: Forty (3.5%) ESBL-producing E. coli were determined as D-ST648, whereas B2-ST131 isolates occurred less frequently (2.8%). Although the predominant ESBL type in both groups was CTX-M-15 (72.5% versus 46.9%), ST648 strains from companion animals and horses displayed a lower variety of ESBL types (CTX-M-1,-3,-14,-15 and-61 versus CTX-M-1,-2,-14,-15,-27 and-55 and SHV-12). In contrast to ST131 strains, a higher proportion of ST648 strains showed resistance to most non-b-lactam antibiotics. Overall, VGs were less abundant in ST648 strains, although some strains had VG profiles comparable to those of ST131 strains. ExPEC-associated serotype O1:H6 was predominant (46.8%) among the ST648 strains. Some PFGE clusters comprised ST648 isolates from pets, horses and wild birds and humans included from previous studies. Conclusions: Our findings demonstrate that certain subgroups of E. coli D-ST648-CTX-M may represent a novel genotype that combines multiresistance, extraintestinal virulence and zoonotic potential.

Original languageEnglish
Article numberdkt516
Pages (from-to)1224-1230
Number of pages7
JournalJournal of Antimicrobial Chemotherapy
Issue number5
Publication statusPublished - 05-2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)


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