title: Isolation of fluoroquinolone-resistant O25b:H4-ST131 Escherichia coli with CTX-M-14 extended-spectrum β-lactamase from UK river water.
abstract: OBJECTIVE
  We analysed water sampled from the River Thames in London for Escherichia coli resistant to oxyimino-cephalosporins and/or fluoroquinolones, particularly seeking isolates with CTX-M extended-spectrum β-lactamases (ESBLs) and members of the clinically important O25b:H4-ST131 lineage.
  
  
  METHODS
  River water was collected from three urban sites on the River Thames by the City of London Port Health Authority on two occasions 1 week apart. Coliforms and E. coli were identified by the Quanti-Tray™ method. Disc susceptibility tests were performed and MICs were determined for E. coli isolates resistant to either ciprofloxacin or cefpodoxime and genetic relatedness was determined by PFGE and real-time PCR. PCR was used for phylogenetic and plasmid typing, to detect antibiotic resistance genes and to detect ISEcp1 upstream of bla(CTX-M) genes. bla(CTX-M) alleles were identified by sequencing.
  
  
  RESULTS
  The mean E. coli count, as the most probable number, from the first river samples, taken on a falling tide on 23 March 2010, was 4.7 × 10(4)/100 mL and 30 ciprofloxacin-resistant colonies were isolated. Twenty of the 30 colonies belonged to clone ST131; 10 of these had bla(CTX-M-14) whereas the remaining 10 lacked ESBLs. The ST131 isolates represented two different PFGE types. No ciprofloxacin- or cefpodoxime-resistant E. coli were isolated from the second river sample taken at low tide. CTX-M-15, the most common ESBL in clinical E. coli, was not detected in the river samples.
  
  
  CONCLUSIONS
  Water from the River Thames in West London is contaminated, perhaps transiently, with antibiotic-resistant E. coli belonging to the clinically important O25b:H4-ST131 lineage.
authors.affiliation: Antibiotic Resistance Monitoring and Reference Laboratory, Microbiology Services-Colindale, Health Protection Agency, 61 Colindale Avenue, London NW9 5EQ, UK. hiran.dhanji@hpa.org.uk
authors.forename: Hiran
authors.initials: H
authors.lastname: Dhanji
authors.forename: Niamh M
authors.initials: NM
authors.lastname: Murphy
authors.forename: Christine
authors.initials: C
authors.lastname: Akhigbe
authors.forename: Michel
authors.initials: M
authors.lastname: Doumith
authors.forename: Russell
authors.initials: R
authors.lastname: Hope
authors.forename: David M
authors.initials: DM
authors.lastname: Livermore
authors.forename: Neil
authors.initials: N
authors.lastname: Woodford
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D008131:London; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D010957:Plasmids; D016133:Polymerase Chain Reaction; D045483:Rivers / Q000382:microbiology*; D001618:beta-Lactamases / Q000096:biosynthesis*; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D047090:beta-Lactams; C456080:beta-lactamase CTX-M-14; D001618:beta-Lactamases