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bla(IMP-4) in different genetic contexts in Enterobacteriaceae isolates from Australia
Björn A Espedido1, Sally R Partridge, Jonathan R Iredell
1Centre for Infectious Diseases & Microbiology, University of Sydney, Westmead Hospital, Westmead, New South Wales 2145, Australia.
Antimicrobial Agents and Chemotherapy
|May 21, 2008
Summary
The IMP-4 metallo-beta-lactamase gene cassette has emerged in Australia. This genetic element spread between bacteria in Sydney and Melbourne, indicating mobile genetic element transfer.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- The metallo-beta-lactamase IMP-4 was first identified in Acinetobacter species in Hong Kong.
- IMP-4-producing Enterobacteriaceae have recently been detected in Australia.
Purpose of the Study:
- To investigate the emergence and genetic context of the IMP-4 metallo-beta-lactamase in Australian Enterobacteriaceae isolates.
- To understand the dissemination mechanisms of the bla(IMP-4)-qacG2-aacA4-catB3 cassette array.
Main Methods:
- Whole-genome sequencing of bacterial isolates.
- Plasmid analysis and characterization.
- Comparative genomic analysis.
Main Results:
- The bla(IMP-4)-qacG2-aacA4-catB3 cassette array was identified in Enterobacteriaceae isolates from Sydney and Melbourne.
- The array was located on different plasmids and within distinct genetic environments in the two cities.
- Evidence suggests homologous recombination facilitated the movement of this array.
Conclusions:
- The IMP-4 metallo-beta-lactamase cassette has successfully disseminated within Australia.
- Mobile genetic elements, particularly plasmids and homologous recombination, play a crucial role in the spread of antimicrobial resistance genes.
