Novel genetic context of multiple blaOXA-58-like genes in Acinetobacter genospecies3

Abstract number: O439

Evans B., Hamouda A., Towner K., Amyes S.

Objectives: The spread of carbapenemase genes within Gram negative bacteria is of great cause for concern. In 2008, the first report of a blaOXA-58 gene outwith Acinetobacter baumannii was reported in Acinetobacter genospecies 3. We had also identified a genospecies 3 isolate encoding a blaOXA-58-like gene, and the aim of this study was to examine the genetic environment of the gene to investigate the mobilisation between species.

Methods: Restriction analysis of rRNA was used to confirm identity to the species level. Susceptibility to imipenem and meropenem was determined through the plate doubling dilution method. Screening by PCR for blaOXA-51-like, blaOXA-23-like, blaOXA-40-like and blaOXA-58-like genes was carried out. Analysis of the genetic environment surrounding the blaOXA-58-like gene was conducted by sequencing inverse PCR products and gene-walking fragments. The structure of the surrounding sequence was confirmed using internal primers, which were also used to screen other blaOXA-58-like positive isolates in our collection.

Results: Restriction analysis confirmed the isolate belonged to Acinetobacter genospecies 3. The isolate showed reduced susceptibility to imipenem and meropenem with MICs of 2 mg/L for both antibiotics. The isolate was negative for a blaOXA-51-like, blaOXA-23-like or blaOXA-40-like gene, but positive for a blaOXA-58-like gene. Analysis of the genetic environment of the blaOXA-58-like gene revealed the gene was within a novel genetic structure. Upstream of the blaOXA-58-like gene was the left-hand end of an ISAba3 element, interrupted by an ISAba125 element. The elements contained putative promoter sequences. Downstream was an araC1 and a lysE gene, followed by a sequence similar to the Re27 element described previously. Following this was a complex region containing the right-hand end of an ISAba3 tnpA gene, interrupted by an incomplete tnpA gene with 99% similarity to ISAba3, itself interrupted by an ISAba125 sequence. This region was followed by a second blaOXA-58-like gene. All other blaOXA-58-like positive isolates in our collection were negative for ISAba125 upstream of blaOXA-58.

Conclusion: This study is the first to report multiple copies of a blaOXA-58-like gene in an Acinetobacter genospecies 3 isolate, and has identified a novel structure containing two blaOXA-58-like genes and two ISAba125 sequences. The ISAba125 elements may be responsible for the duplication of the blaOXA-58-like gene.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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