Intercontinental emergence of Escherichia coli clone O25:H4-ST131 producing CTX-M-15.
BACKGROUND
Concomitant with the recent emergence of CTX-M-type extended-spectrum beta-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.
Nicolas-Chanoine
Marie-Hélène
MH
Service de Microbiologie, Hôpital AP-HP Beaujon, 92110 Clichy, France. mhn.chanoine@bjn.aphp.fr
Blanco
Jorge
J
Leflon-Guibout
Véronique
V
Demarty
Raphael
R
Alonso
Maria Pilar
MP
Caniça
Maria Manuela
MM
Park
Yeon-Joon
YJ
Lavigne
Jean-Philippe
JP
Pitout
Johann
J
Johnson
James R
JR
D002999:Clone Cells / Q000201:enzymology / Q000502:physiology; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000302:isolation & purification; D005838:Genotype; D014943:Global Health; D006801:Humans; D001618:beta-Lactamases / Q000235:genetics* / Q000302:isolation & purification
D029968:Escherichia coli Proteins; C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases