Description of novel allelic variants of the chromosomal gene blaOXA-114-like in Achromobacter xylosoxidans clinical isolates

TRAGLIA G.; ALMUZARA M.N.; PAPALIA M.; RADICE M.; CENTRON D.; VAY C.A.; RAMIREZ M.S.

San Francisco

Congreso; ICAAC 2012; 2012

American Society for Microbiology

Infections due to A. xylosoxidans have been increasingly documented in immunocompromised and cystic fibrosis patients. Since misidentification of A. xylosoxidans is frequent, PCR amplification of blaOXA-114 gene has been proposed for specific identification of this specie. We decided to confirm the presence of this gene and also to describe the potential different allelic variants among clinical isolates of A. xylosoxidans recovered in our region. PCR amplification and amplicon sequencing were conducted to determine the presence of blaOXA-114-like genes in a collection of 23 non-epidemiological related clinical isolates of A. xylosxosidans. One A. denitrificans and one A. piechaudii isolates were used as negative controls. All PCR amplification products were sequenced on both DNA strands using an ABIPrism 3100 BioAnalyzer and Taq FS Terminator Chemistry (Taq FS, Perkin-Elmer) and sequences analysis were performed with the Sequencher 4.7 (Gene Codes Corp.), BLAST (version 2.0) (http://www.ncbi.nlm.nih.gov/BLAST/), clustalX (version 2.1) and Mega5 softwares. Positive amplification results were obtained for all A. xylosoxidans clinical isolates. Nucleotide sequence analysis revealed the presence of 15 new blaOXA-114 alleles, being 5 of them synonymous mutation (n=23). Previous described variants were also present among A. xylosxosidans isolates included in this study. We found the variants a, c, e, f and g, being the f variant the most widespread (n=7) in our population. In one isolate, AX79, the blaOXA sequence obtained was 100 % identical to the oxacillin hydrolase class D beta-lactamase of the A. xylosxosidans AXX-A (AN EGP47223); designated in this study as OXA-x. The analysis at protein level, exposed the presence of 6 new OXA-114 variants. Our results showed the presence of different novel variants of this gene, exposing its great variability since 15 new alleles were found. As blaOXA-114 is ubiquitously present in all A. xylosxosidans clinical isolates tested, our results suggest that this specie is a potential reservoir of new antibiotic resistance genes.