Novel genetic context of multiple bla OXA-58 genes in Acinetobacter genospecies 3.
OBJECTIVE
The detection in Acinetobacter genospecies 3 isolates of OXA-type carbapenemases, resulting in reduced susceptibility to carbapenem antibiotics, is increasingly reported. We identified an Acinetobacter genospecies 3 isolate carrying the gene for OXA-58 and aimed to resolve the genetic environment surrounding the bla(OXA-58) gene.


METHODS
Species identification was confirmed by 16S-23S rRNA restriction analysis. MICs of imipenem, meropenem and ertapenem were determined, and the isolate was screened by PCR for bla(OXA-23-like), bla(OXA-40-like), bla(OXA-51-like) and bla(OXA-58-like) genes. The sequence surrounding bla(OXA-58) was determined through amplification by inverse PCR and genome walking followed by sequencing. Genetic localization was investigated by Southern blotting.


RESULTS
Isolate A164 was confirmed as belonging to Acinetobacter genospecies 3 and had reduced susceptibility to the carbapenems. The isolate was found to encode two bla(OXA-58) genes that may have been duplicated by the insertion sequence ISAba125, two copies of which were inserted into ISAba3 elements. The bla(OXA-58) genes appear to be plasmid borne.


CONCLUSIONS
This is the first report of beta-lactamase duplication in Acinetobacter genospecies 3 and of gene duplication mediated by ISAba125.
Evans
B A
BA
Faculty of Life Sciences, The University of Manchester, Manchester, UK.
Hamouda
A
A
Towner
K J
KJ
Amyes
S G B
SG
D000150:Acinetobacter / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D000151:Acinetobacter Infections / Q000382:microbiology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015139:Blotting, Southern; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics*; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D000077727:Ertapenem; D020440:Gene Duplication; D023061:Gene Order; D005798:Genes, Bacterial; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D013845:Thienamycins / Q000494:pharmacology; D001618:beta-Lactamases / Q000235:genetics*; D047090:beta-Lactams / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D021903:DNA, Ribosomal Spacer; D013845:Thienamycins; D047090:beta-Lactams; D015378:Imipenem; D001618:beta-Lactamases; C534889:beta-lactamase OXA-58, Acinetobacter baumannii; D000077731:Meropenem; D000077727:Ertapenem