title: Detection of Pseudomonas aeruginosa isolates producing VEB-type extended-spectrum beta-lactamases in the United Kingdom.
abstract: OBJECTIVE
  The aim of this study was to investigate the presence of VEB enzymes among Pseudomonas spp. referred to the UK's national reference laboratory and with phenotypic evidence of extended-spectrum beta-lactamase (ESBL) production.
  
  
  METHODS
  Antibiograms were analysed for Pseudomonas spp. referred from November 2003 to November 2007. Isolates with >/=4-fold ceftazidime/clavulanate synergy were screened for bla(VEB) alleles. Genes encoding metallo-beta-lactamases (bla(MBL)) were sought in isolates with positive imipenem/EDTA synergy tests. Selected PCR products were sequenced. PFGE of SpeI-digested genomic DNA was used to compare isolates.
  
  
  RESULTS
  Forty-nine (3.7%) of 1338 Pseudomonas spp. were considered potential ESBL producers; 40 were recovered for molecular testing. bla(VEB) alleles were detected in 32 Pseudomonas aeruginosa isolates, comprising diverse PFGE types, from 12 UK hospitals and 1 in India. One UK centre referred 15 isolates with VEB-1 enzyme; these were serotype O15, representing a single PFGE-defined strain that also produced VIM-10 metallo-carbapenemase. This strain was resistant to all beta-lactams, aminoglycosides and ciprofloxacin, remaining susceptible only to colistin (MICs </=1 mg/L). Two other P. aeruginosa isolates co-producing both VEB and VIM enzymes were received from two other UK hospitals; one isolate represented inter-hospital spread of the O15 strain and the second was distinct.
  
  
  CONCLUSIONS
  VEB enzymes have not been reported previously in the UK, but were produced by 80% of Pseudomonas spp. with phenotypic evidence of ESBL production. They co-existed with VIM carbapenemases in two strains, with one responsible for a major hospital outbreak. The incidence of ESBLs may be underestimated in Pseudomonas because ESBL phenotypes can be masked by other beta-lactam resistance mechanisms.
authors.affiliation: Centre for Infections, Health Protection Agency, 61 Colindale Avenue, London NW9 5EQ, UK.
authors.forename: Neil
authors.initials: N
authors.lastname: Woodford
authors.forename: Jiancheng
authors.initials: J
authors.lastname: Zhang
authors.forename: Mary E
authors.initials: ME
authors.lastname: Kaufmann
authors.forename: Susannah
authors.initials: S
authors.lastname: Yarde
authors.forename: Maria Del Mar
authors.initials: Mdel M
authors.lastname: Tomas
authors.forename: Camelia
authors.initials: C
authors.lastname: Faris
authors.forename: Madhur S
authors.initials: MS
authors.lastname: Vardhan
authors.forename: Susan
authors.initials: S
authors.lastname: Dawson
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Cotterill
authors.forename: David M
authors.initials: DM
authors.lastname: Livermore
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004196:Disease Outbreaks; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D005838:Genotype; D006761:Hospitals; D006801:Humans; D007194:India; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D011552:Pseudomonas Infections / Q000382:microbiology* / Q000635:transmission; D011550:Pseudomonas aeruginosa / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D017422:Sequence Analysis, DNA; D012703:Serotyping; D006113:United Kingdom; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D001618:beta-Lactamases