title: Epidemiology of the Acinetobacter-derived cephalosporinase, carbapenem-hydrolysing oxacillinase and metallo-β-lactamase genes, and of common insertion sequences, in epidemic clones of Acinetobacter baumannii from Spain.
abstract: OBJECTIVE
  To study the distribution, diversity and activity of Acinetobacter-derived cephalosporinase (ADC)-, carbapenem-hydrolysing oxacillinase (CHO)- and metallo-β-lactamase (MBL)-encoding genes, and of the most common insertion sequences (ISs), in the genome of nosocomial, epidemic, multidrug-resistant Acinetobacter baumannii (MDRAB) clones from Spain.
  
  
  METHODS
  The studied population included 59 MDRAB strains previously genotyped by PFGE and multilocus sequence typing. The search for the ADC (bla(ADC)), CHO (bla(OXA-51-like), bla(OXA-23-like), bla(OXA-40-like) and bla(OXA-58-like)) and MBL (bla(IMP), bla(VIM), bla(SIM-1), bla(GIM-1), bla(SPM-1) and bla(NDM-1)) genes, and for the ISs (ISAba1, ISAba2, ISAba3, ISAba4 and IS18) was done by PCR assays. The phenotypic presence of MBL enzymes was examined using imipenem/imipenem + EDTA strips.
  
  
  RESULTS
  The most prevalent IS, ISAba1 (93.2%), was detected upstream of bla(ADC) and bla(OXA-51-like). These genes showed ample diversity (10 and 8 alleles, respectively). Four ADC sequences (ADC-1-like(P240S), ADC-2-like(N260H/T264N), ADC-11-like(Q163K) and ADC-11-like(G342R)) are described here for the first time. bla(OXA-58-like) was carried by 20.3% of strains, in association with ISAba2, ISAba3 or IS18. bla(OXA-40-like) was the most prevalent acquired CHO gene (57.6%), and was associated with none of the studied ISs. Neither bla(OXA-23-like) nor ISAba4 was detected in any strain. Some 67.8% of strains with MBL activity showed no corresponding gene in PCR; these results were more common in strains with a highly active CHO, such as OXA-40.
  
  
  CONCLUSIONS
  All the studied genes and their related ISs showed a clonal distribution. Imipenem resistance was probably provided by OXA-40 for the most part, while MBL- and OXA-23-encoding genes were absent in the studied population.
authors.affiliation: Laboratorio de Taxonomía, Servicio de Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain. pvillalon@isciii.es
authors.forename: Pilar
authors.initials: P
authors.lastname: Villalón
authors.forename: Sylvia
authors.initials: S
authors.lastname: Valdezate
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Medina-Pascual
authors.forename: Gema
authors.initials: G
authors.lastname: Carrasco
authors.forename: Ana
authors.initials: A
authors.lastname: Vindel
authors.forename: Juan A
authors.initials: JA
authors.lastname: Saez-Nieto
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology* / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D016000:Cluster Analysis; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D058889:Molecular Typing; D016133:Polymerase Chain Reaction; D013030:Spain / Q000453:epidemiology; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D001618:beta-Lactamases