Prevalence and Characterization of Extended-Spectrum Beta-lactamases-Producing Salmonella enterica Isolates in Saragossa, Spain (2001–2008)

María Pardos de La Gándara (1, 2) , Cristina Seral (2) , Javier Castillo García (2) , Carmen Rubio Calvo (2) , François-Xavier Weill (1)

1 CNR - Centre National de Référence des Salmonella - Bactéries pathogènes entériques
2 University of Zaragoza - Universidad de Zaragoza [Zaragoza]

We analyzed the prevalence of resistance to extended-spectrum cephalosporins (ESCs) among clinical strains of Salmonella enterica collected by the Laboratory of Clinical Microbiology in the University Clinical Hospital Lozano Blesa in the region of Aragó n (Spain), for which very few epidemiological information exists. A total of 2,092 strains of S. enterica were identified in stool samples from patients with gastroenteritis. Five isolates showed an extended-spectrum beta-lactamase (ESBL) phenotype: four isolates of S. enterica serotype Virchow harbored the ESBL-encoding bla CTX-M-9 gene and an isolate of serotype Enteritidis carried a bla CTX-M-1 gene, which, to the best of our knowledge, is described here for the first time in this serotype of S. enterica. The five ESC-resistant isolates were also resistant to spectinomycin, streptomycin, kanamycin, sulfonamides, tetracycline, and trimethoprim as well as to nalidixic acid. The ESBL isolate of serotype Enteritidis, however, remained susceptible to kanamycin and nalidixic acid. A class 1 integron of 1.5 kb was detected for the four serotype Virchow isolates with the gene cassette dfrA16–aadA2. The bla CTX-M-9 gene was carried by an *300-kb IncHI2 conjugative plasmid in the case of the S. enterica serotype Virchow isolates. The bla CTX-M-1 gene was carried by an *100-kb IncI1-N conjugative plasmid for the serotype Enteritidis ESC-resistant isolate. All the four ESC-resistant strains of S. enterica serotype Virchow clustered together in a XbaI pulsed-field gel electrophoresis, which also revealed a strong similarity between them and some pulsotypes of S. enterica serotype Virchow from France.

Domains: Santé publique et épidémiologie

María Pardos de La Gándara, Cristina Seral, Javier Castillo García, Carmen Rubio Calvo, François-Xavier Weill. Prevalence and Characterization of Extended-Spectrum Beta-lactamases-Producing Salmonella enterica Isolates in Saragossa, Spain (2001–2008). Microbial Drug Resistance, 2011, 17 (2), pp.207-13. ⟨10.1089/mdr.2010.0105⟩. ⟨pasteur-01131166⟩