title: Epidemiology and carbapenem resistance mechanisms of carbapenem-non-susceptible Pseudomonas aeruginosa collected during 2009-11 in 14 European and Mediterranean countries.
abstract: OBJECTIVE
  To evaluate the genetic relatedness and carbapenem resistance mechanisms among carbapenem-non-susceptible Pseudomonas aeruginosa collected during 2009-11 in 14 European and Mediterranean countries.
  
  
  METHODS
  Doripenem-non-susceptible (MIC >2 mg/L) isolates were tested for susceptibility to imipenem, meropenem, doripenem, aztreonam, ceftazidime and cefepime with and without phenyl-arginine-β-naphthylamide (PAβN) (efflux inhibitor) and/or cloxacillin (AmpC inhibitor). Carbapenemase screening was performed by PCR and sequencing. Expression of chromosomal ampC, mexA, mexC, mexE and mexX was determined by quantitative real-time PCR using P. aeruginosa PAO1 or a group of susceptible isolates as baseline. Clonality was evaluated by PFGE and multilocus sequence typing.
  
  
  RESULTS
  Among 529 (25.6% overall) carbapenem-non-susceptible P. aeruginosa, 106 were positive for metallo-β-lactamase (MβL) genes encoding VIM-2 (76 strains), VIM-4 (14), VIM-1 (7) and VIM-5 (5). IMP-15 and three new MβLs (IMP-33, VIM-36 and VIM-37) were detected in one strain each. An increasing prevalence of MβL producers was noted in 2011 (30.6%) compared with previous years (13.4% and 12.3% in 2009 and 2010, respectively). Isolates displayed high genetic diversity, with 401 unique profiles detected. CC235 and ST111 were detected among MβL-producing clusters. The PAβN/cloxacillin effect ranged from 90.0% to 56.5%/from 1.3% to 21.2%. OprD decrease/loss was the most prevalent intrinsic mechanism and was detected among 94.9% of the P. aeruginosa, followed by AmpC (44.4%) and MexAB-OprM (20.1%). When using the susceptible group of isolates as baseline, MexAB-OprM became as prevalent as OprD decrease/loss.
  
  
  CONCLUSIONS
  Increasing MβL prevalence is worrisome in various European countries; however, intrinsic resistance mechanisms in a highly genetically diverse population of carbapenem-non-susceptible P. aeruginosa are probably a matter for greater concern in these countries.
authors.affiliation: JMI Laboratories, North Liberty, IA 52317, USA mariana-castanheira@jmilabs.com.
authors.forename: Mariana
authors.initials: M
authors.lastname: Castanheira
authors.affiliation: JMI Laboratories, North Liberty, IA 52317, USA.
authors.forename: Lalitagauri M
authors.initials: LM
authors.lastname: Deshpande
authors.affiliation: JMI Laboratories, North Liberty, IA 52317, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Costello
authors.affiliation: Janssen Research & Development, Raritan, NJ 08869, USA.
authors.forename: Todd A
authors.initials: TA
authors.lastname: Davies
authors.affiliation: JMI Laboratories, North Liberty, IA 52317, USA.
authors.forename: Ronald N
authors.initials: RN
authors.lastname: Jones
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005060:Europe; D020869:Gene Expression Profiling; D005838:Genotype; D006801:Humans; D019083:Mediterranean Region; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D016133:Polymerase Chain Reaction; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D018440:beta-Lactam Resistance
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D004269:DNA, Bacterial
keywords: Europe; P. aeruginosa; carbapenem resistance