title: Prevalence and characterization of extended-spectrum beta-lactamases-producing Salmonella enterica isolates in Saragossa, Spain (2001-2008).
abstract: 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 Aragón (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.
authors.affiliation: Institut Pasteur, Laboratoire des Bactéries Pathogènes Entériques, Centre National de Référence des Salmonella, Paris, France. mariapardos@yahoo.es
authors.forename: María
authors.initials: M
authors.lastname: Pardos de la Gándara
authors.forename: Cristina
authors.initials: C
authors.lastname: Seral
authors.forename: Javier
authors.initials: J
authors.lastname: Castillo García
authors.forename: Carmen
authors.initials: C
authors.lastname: Rubio Calvo
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Weill
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D002511:Cephalosporins / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D005243:Feces / Q000382:microbiology; D005759:Gastroenteritis / Q000453:epidemiology / Q000382:microbiology* / Q000473:pathology; D006801:Humans; D032023:Integrons / Q000187:drug effects / Q000235:genetics; D008826:Microbial Sensitivity Tests; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D015995:Prevalence; D012189:Retrospective Studies; D012480:Salmonella Infections / Q000453:epidemiology / Q000382:microbiology* / Q000473:pathology; D019779:Salmonella enterica / Q000145:classification / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development / Q000302:isolation & purification; D013030:Spain; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D001618:beta-Lactamases