Co-Occurrence of ACSSuT and Cephalosporin Resistance Phenotypes Is Mediated by int1-Associated Elements in Nontyphoidal Salmonella enterica from Human Infections in Spain

• Published in: Microbial drug resistance (Larchmont, N.Y.) Vol. 19; no. 5; pp. 384 - 391
• Main Authors: Campos, Maria Jorge, Palomo, Gonzalo, Hormeño, Lorena, Ugarte, María, Porrero, María Concepción, Herrera-León, Silvia, Vadillo, Santiago, Píriz, Segundo, Quesada, Alberto
• Format: Journal Article
• Language: English
• Published: United States Mary Ann Liebert, Inc 01.10.2013
• Subjects: Anti-Bacterial Agents - therapeutic use; Antimicrobial agents; beta-Lactamases - genetics; beta-Lactamases - metabolism; Cephalosporin Resistance - drug effects; Cephalosporin Resistance - genetics; Cephalosporins - therapeutic use; Conjugation, Genetic; Drug resistance; Drug Resistance, Multiple, Bacterial - drug effects; Drug Resistance, Multiple, Bacterial - genetics; Epidemiology; Gene Expression Regulation, Bacterial - drug effects; Genotype & phenotype; Humans; Salmonella; Salmonella enterica; Salmonella enteritidis; Salmonella enteritidis - drug effects; Salmonella enteritidis - genetics; Salmonella enteritidis - isolation & purification; Salmonella Infections - drug therapy; Salmonella Infections - epidemiology; Salmonella Infections - microbiology; Salmonella typhimurium; Salmonella typhimurium - drug effects; Salmonella typhimurium - genetics; Salmonella typhimurium - isolation & purification; Serotyping; Spain - epidemiology; Spain
• ISSN: 1076-6294; 1931-8448
• DOI: 10.1089/mdr.2012.0261

A screening of antimicrobial resistance and its genetic determinants has been performed on 300 Salmonella enterica isolates collected during 2004–2008 from human infections in Spain. Salmonella Typhimurium and Salmonella Enteritidis were the major serotypes, which were found with similar frequencies covering 80% of the bacterial collection. Salmonella Typhimurium isolates frequently shared low susceptibility to antimicrobials of the penta-resistance phenotype (ACSSuT) and/or cephalosporin resistance. The ACSSuT profile was found closely linked to int1 -associated gene cassettes, with major elements carrying DNA fragments of 1.0 Kb ( aadA2 gene) plus 1.2 Kb ( blaPSE -1 gene) or 2.0 Kb ( aadA1 and blaOXA -1 genes). Among these, ACSSuT and cephalosporin resistances were associated in Salmonella Typhimurium isolates expressing the blaOXA gene. β-lactamase activities were also detected from isolates carrying blaTEM , blaCMY , or blaSHV , although only the two last genes expressed extended-spectrum β-lactamases. The clonal analysis of S. enterica strains suggests that both horizontal and vertical transfer mechanisms are involved in the wide dissemination of their antimicrobial resistance.