A 63-kb genomic resistance island in an Acinetobacter baumannii isolate from 1977

Abstract number: P793

Objective: Multidrug resistance in Acinetobacter baumannii has been significantly associated with a few international clonal lineages. Multidrug-resistant (MDR) strains of two of these lineages (EU clones I and II) have occurred in European hospitals since at least the 1980s. Three large (86 kb, 63 kb and 56 kb), stucturally related genomic resistance islands (AbaR1, AbaR3 and AbaR5, respectively) integrated into the ATPase gene were recently found in EU clone I strains isolated between 1997 and 2004. The aim of this study was to assess whether a MDR outbreak strain of EU clone I isolated in 1977 harbours an AbaR-like resistance island.

Methods: Strain HK302 was isolated during a hospital outbreak in Switzerland in 1977 (Antimicrob Agents Chemother 1982; 22: 323) and later was allocated to EU clone I. Strain AYE harbouring AbaR1 was used as a positive control for the detection of AbaR1-associated genes and PCR mapping. Disruption of the ATPase gene was determined using PCR with primers derived from both ends of the gene. The presence of 29 AbaR1-associated genes was investigated by PCR using primers inferred from the sequence of AbaR1. PCR mapping using the Long Range PCR kit (Qiagen) was performed, followed by RFLP analysis of amplicons. The regions different from those of AbaR1 were sequenced.

Results: A genomic region inserted into the ATPase gene at the same position as known for AbaR1 was found in HK302. In addition, 18 AbaR1-associated genes were identified in this strain. PCR mapping combined with RFLP analysis revealed that HK302 harboured a 63-kb resistance island which shared regions of a total size of 57 kb with AbaR1. Two segments (sized 4 kb and 2 kb) different from those of AbaR1 were sequenced and found to correspond to the regions described in AbaR3, i.e. one comprising the topoisomerase topA gene and the other a transposon carrying blaTEM-1.

Conclusion: An AbaR3-like resistance island was identified in HK302, which indicates that highly complex resistance islands existed in EU clone I strains already in the late 1970s.

Supported by grant 310/08/1747 of the Grant Agency of the Czech Republic.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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