International dissemination of extended-spectrum b-lactamase TEM-24 among Enterobacteriaceae species is caused by spread of both epidemic IncA/C2 plasmid and strains

Abstract number: 1733_532

Novais A., Cantón R., Machado E., Peixe L., Baquero F., Coque T.M.

Objectives: TEM-24 is one of the TEM-type ESBL most widespread in Europe. The aim of this study was to characterise TEM-24-producing Enterobacteriaceae isolates recovered in different European countries and genetic elements participating on this ESBL dissemination.

Methods: Twenty five TEM-24-producing isolates recovered during a period of six years (1998–2004) from Spain (n = 11), Portugal (n = 11), and France (n = 3) were studied. Only one isolate/phenotype was included. They were Escherichia coli and Klebsiella pneumoniae (n = 6 each), and Enterobacter aerogenes (n = 13). Isolates were obtained from patients at medical wards (57.1%), ICUs (19.1%), surgical wards (9.5%), and 14.3% were outpatients. ESBL characterisation was performed by IEF, PCR and further sequencing. Relationship among isolates was established by PFGE and E. coli phylogenetic groups were searched as reported. Antibiotic susceptibility testing and conjugation assays were performed using standard methods. Integrons were determined as described. Plasmid characterisation included analysis of RFLP patterns and determination of incompatibility group by PCR, hybridisation and sequencing.

Results:E. coli isolates (n = 6) were assigned to six PFGE types whereas K. pneumoniae and E. aerogenes isolates were each associated with an epidemic clone. E. coli isolates belong to phylogroups D (75%) and A (25%). Most strains were resistant to tobramycin, amikacin and nalidixic acid. blaTEM-24 was located in a 170kb-IncA/C2 conjugative plasmid in all cases. Related plasmid RFLP patterns were observed among distinct Enterobacterial isolates, suggesting a common plasmid background involved in TEM-24 dissemination. This plasmid contain class 1 integron carrying aacA4 gene cassette.

Conclusions: Intercountry spread of blaTEM-24 is determined either by E. aerogenes or K. pneumoniae epidemic strains or by epidemic plasmids among Enterobacteriaceae species. Location on broad host range IncA/C2 plasmid might enables further transmission to other hosts.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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