Intercontinental emergence of Escherichia coli clone O25:H4-ST131 producing CTX-M-15

Marie Hélène Nicolas-Chanoine, Jorge Blanco, Véronique Leflon-Guibout, Raphael Demarty, Maria Pilar Alonso, Maria Manuela Caniça, Yeon Joon Park, Jean Philippe Lavigne, Johann Pitout, James R. Johnson

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698 Scopus citations


Background: Concomitant with the recent emergence of CTX-M-type extended-spectrum β-lactamases (ESBLs), Escherichia coli has become the enterobacterial species most affected by ESBLs. Multiple locales are encountering CTX-M-positive E. coli, including specifically CTX-M-15. To gain insights into the mechanism underlying this phenomenon, we assessed clonality and diversity of virulence profiles within an international collection of CTX-M-15-positive E. coli. Methods: Forty-one ESBL-positive E. coli isolates from eight countries and three continents (Europe, Asia and North America) were selected for study based on suspected clonality. Phylogenetic group, ERIC2 PCR profile, O H serotype, AmpC variant and antibiotic susceptibility were determined. Multilocus sequence typing (MLST) and PFGE provided additional discrimination. Virulence potential was inferred by detection of 46 virulence factor (VF) genes. Results: Thirty-six (88%) of the 41 E. coli isolates exhibited the same set of core characteristics: phylogenetic group B2, ERIC2 PCR profile 1, serotype O25:H4, AmpC EC6, ciprofloxacin resistance and MLST profile ST131. By PFGE, the 36 isolates constituted one large cluster at the 68% similarity level; this comprised 17 PFGE groups (defined at 85% similarity), some of which included strains from different countries. The 36 isolates exhibited highly (91% to 100%) similar VF profiles. Conclusions: We describe a broadly disseminated, CTX-M-15-positive and virulent E. coli clonal group with highly homogeneous virulence genotypes and subgroups exhibiting highly similar PFGE profiles, suggesting recent emergence. Understanding how this clone has emerged and successfully disseminated within the hospital and community, including across national boundaries, should be a public health priority.

Original languageEnglish (US)
Pages (from-to)273-281
Number of pages9
JournalJournal of Antimicrobial Chemotherapy
Issue number2
StatePublished - Feb 2008

Bibliographical note

Funding Information:
This study was supported by a grant (AOR 04016) from La Direction de le Recherche Clinique de l’Assistance Publique-Hôpitaux de Paris (M.-H. N.-C.), a grant (PI052023-PI051481) from Fondo de Investigacion Sanitaria (FIS), Instituto de Salud Carlos III, Spanish Ministerio de Sanidad y Consumo (J. B.) and Office of Research and Development, Medical Research Service, Department of Veterans Affairs (J. R. J.).


  • E. coli
  • Enterobacteria
  • Multidrug resistance


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