title: Characterisation of carbapenem-resistance mechanisms in clinical Pseudomonas aeruginosa isolates recovered in a Spanish hospital.
abstract: BACKGROUND
  Carbapenems are the beta-lactam antibiotics with the best spectrum of activity in the treatment of Pseudomonas aeruginosa infections. The objective of this study was to molecularly characterise a collection of carbapenem-resistant P. aeruginosa isolates (PARC).
  
  
  METHODS
  A total of 85 PARC isolates were recovered from 60patients in the Hospital San Pedro, Logroño (period 2008-2011). Clonal relationship was determined using pulsed-field gel electrophoresis (PFGE), susceptibility testing to 15anti-pseudomonal agents was performed using the disk diffusion method, and alterations in oprD, characterisation of integrons and molecular typing (MLST) using PCR and sequencing.
  
  
  RESULTS
  The 85 PARC were classified into 35 different PFGE profiles. Of the 61selected strains from 60patients all of them were multiresistant, although none of them showed a carbapenemase phenotype. High polymorphism was detected in OprD, emphasising that 59% of the strains had a premature stop codon. ISPa1328 and ISPsp4 insertion sequences truncated oprD gene into 2 strains (GenBank KF517097 and KF517098). Two-thirds (67%) of the strains showed class 1 integrons with genes encoding aminoglycoside modifying enzymes, and 2 of them carried a new integron: aac(3)-Ia+aadA1h, named In272, GenBank GQ144317. Four sequence types were detected (Strain Nos.): ST175 (35), ST308 (3), ST235 (2), and ST639 (1).
  
  
  CONCLUSIONS
  Multidrug resistance, high polymorphism in oprD, a high percentage of integrons, moderate clonal relationship of strains, and the high epidemic dissemination of high-risk clones are clinical aspects of great concern in order to eradicate the spread of PARC.
authors: Área de Bioquímica y Biología Molecular, Universidad de La Rioja, Logroño, España.
authors: Vanesa
authors: V
authors: Estepa
authors: Área de Microbiología Molecular, Centro de Investigación Biomédica de La Rioja (CIBIR), Logroño, España.
authors: Beatriz
authors: B
authors: Rojo-Bezares
authors: Departamento de Diagnóstico Biomédico, Laboratorio de Microbiología, Hospital San Pedro, Logroño, España.
authors: Jose Manuel
authors: JM
authors: Azcona-Gutiérrez
authors: Departamento de Diagnóstico Biomédico, Laboratorio de Microbiología, Hospital San Pedro, Logroño, España.
authors: Inés
authors: I
authors: Olarte
authors: Área de Bioquímica y Biología Molecular, Universidad de La Rioja, Logroño, España; Área de Microbiología Molecular, Centro de Investigación Biomédica de La Rioja (CIBIR), Logroño, España.
authors: Carmen
authors: C
authors: Torres
authors: Área de Microbiología Molecular, Centro de Investigación Biomédica de La Rioja (CIBIR), Logroño, España. Electronic address: ysaenz@riojasalud.es.
authors: Yolanda
authors: Y
authors: Sáenz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015780:Carbapenems / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D005260:Female; D006761:Hospitals; D006801:Humans; D008297:Male; D008875:Middle Aged; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology; D055815:Young Adult
chemical_list: D015780:Carbapenems
keywords: Integron; Integrón; Porin OprD; Porina OprD; ST175; aadB