JAC Advance Access published online on October 3, 2007
Journal of Antimicrobial Chemotherapy, doi:10.1093/jac/dkm381
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High diversity of extended-spectrum ß-lactamases among clinical isolates of Enterobacteriaceae from Portugal
1 REQUIMTE, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal 2 Servicio de Microbiología, Hospital Universitario Rámon y Cajal, IMSALUD, Madrid, Spain 3 Faculdade de Ciências da Saúde, Universidade Fernando Pessoa, Porto, Portugal
Received 20 February 2007; returned 8 May 2007; revised 6 September 2007; accepted 10 September 2007
* Correspondence address. Laboratório de Microbiologia, Faculdade de Farmácia da Universidade do Porto, Rua Aníbal Cunha 164, Porto 4050, Portugal Tel: +351-22-200-89-46; Fax: +351-22-200-39-77; E-mail: lpeixe{at}ff.up.pt
Objectives: To investigate the occurrence and the diversity of Ambler class A ESBLs among Enterobacteriaceae from different Portuguese clinical settings over a 2 year period (2002–04).
Methods: One hundred and nine extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae isolates from five geographically distant health institutions in Portugal were studied. ESBLs were characterized by isoelectric focussing, PCR and further sequencing. Antibiotic susceptibility testing, transfer of resistance genes and clonal diversity were determined by standard procedures. Plasmid relatedness was established by comparison of random amplified polymorphic DNA (RAPD) patterns.
Results: ESBLs were identified as TEM (46%), SHV (30%), CTX-M (22%) and GES (2%) types; TEM-24, TEM-52, SHV-12 and CTX-M-15 enzymes being the most frequently found. Inter-hospital dissemination of epidemic strains harbouring the most prevalent ESBLs was detected, including the TEM-24-producing Enterobacter aerogenes European epidemic clone. Conjugative transfer of ESBLs was achieved for 67% of isolates and epidemic plasmids containing specific bla genes were detected (blaCTX-M-15 and blaTEM-24). We describe two new ESBLs, SHV-90 (A187T, G238S and E240K) and SHV-91 (P20S and E240K), and a new TEM-type enzyme conferring a phenotype resembling that of a complex mutant TEM ß-lactamase, designated as TEM-154 (M69L and R164S). The broad-spectrum ß-lactamases SHV-26, SHV-36 and TEM-110 were first observed in our country.
Conclusions: We describe a complex ESBL epidemiology in Portugal, including widespread dissemination of known strains and plasmids coding for TEM-24 and CTX-M-15 enzymes as observed in other European countries.
Key Words: TEM , SHV , CTX-M-15 , clonal dissemination , epidemic plasmids , ESBLs epidemiology
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