High Prevalence of OXA-51-type Class D Beta-Lactamases Among Ceftazidime-Resistant Clinical Isolates of Acinetobacter Spp.: Co-Existence With OXA-58 in Multiple Centres

J Antimicrob Chemother. 2006 Sep;58(3):537-42. doi: 10.1093/jac/dkl273. Epub 2006 Jul 1.

Abstract

Objectives: This study was designed to demonstrate the prevalence of the newly discovered carbapenem-hydrolysing class D enzymes, OXA-51-type and OXA-58, among clinical isolates of Acinetobacter spp.

Methods: A total of 72 isolates from six centres were studied. Isolates were screened by PCR with specific primers for bla(OXA-51-type) and bla(OXA-58). PCR products were sequence-analysed. Plasmids were digested with EcoRV and genomic DNAs were digested with PvuII. Hybridization experiments were done with digoxigenin-labelled specific probes. Macro-restriction analysis was done on SmaI-digested genomic DNAs.

Results: A total of 56 (77.8%) isolates were positive for bla(OXA-51-type) genes. Sequence analysis of the products from 23 selected isolates revealed the occurrence of multiple alleles in all contributing centres. The bla(OXA-58) gene was detected among 10 isolates from five centres. All were also positive for bla(OXA-51-type) genes. Among the bla(OXA-58)-positive isolates, two from the same centre were positive for a novel OXA-51 allele (OXA-86). Southern hybridization of plasmids and of genomic DNAs suggested that bla(OXA-51-type) genes are located on chromosomes whereas bla(OXA-58) genes are plasmid borne in these 10 isolates. Plasmid profiles and pulsed-field gel electrophoresis patterns indicated the spread of the bla(OXA-58) gene among multiple clones. The bla(OXA-51-type) and bla(OXA-58) co-carrier strains were mostly associated with a pandrug-resistant phenotype.

Conclusions: This study indicated that bla(OXA-58)-bearing plasmids are readily spreading among multiple clones of the bla(OXA-51-type)-bearing clinical isolates of Acinetobacter spp. Since these isolates are highly resistant to antibiotics this finding indicates the existence of a significant problem in Turkish hospitals.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter / drug effects
  • Acinetobacter / enzymology
  • Acinetobacter / genetics
  • Acinetobacter / isolation & purification*
  • Acinetobacter Infections / epidemiology*
  • Acinetobacter Infections / microbiology
  • Alleles
  • Anti-Bacterial Agents / pharmacology*
  • Blotting, Southern
  • Ceftazidime / pharmacology*
  • Cross Infection / epidemiology*
  • Cross Infection / microbiology
  • DNA, Bacterial / genetics
  • Electrophoresis, Gel, Pulsed-Field
  • Genes, Bacterial
  • Hospitals, University
  • Humans
  • Microbial Sensitivity Tests
  • Molecular Sequence Data
  • Polymerase Chain Reaction
  • Prevalence
  • Turkey / epidemiology
  • beta-Lactam Resistance* / genetics
  • beta-Lactamases / genetics*

Substances

  • Anti-Bacterial Agents
  • DNA, Bacterial
  • Ceftazidime
  • beta-Lactamases

Associated data

  • GENBANK/DQ348075