Emergence of Salmonella genomic island 1 (SGI1) among Proteus mirabilis clinical isolates in Dijon, France

Abstract

Objectives: Salmonella genomic island 1 (SGI1) is often encountered in antibiotic-resistant Salmonella enterica and exceptionally in Proteus mirabilis. We investigated the prevalence of SGI1-producing clinical isolates of P. mirabilis in our hospital (Dijon, France). Methods: A total of 57 strains of P. mirabilis resistant to amoxicillin and/or gentamicin and/or trimethoprim/ sulfamethoxazole isolated from August 2011 to February 2012 as well as 9 extended-spectrum b-lactamase (ESBL)-producing P. mirabilis from our collection were tested for the presence of SGI1 by PCR. The complete SGI1 structure from positive isolates [backbone and multidrug resistance (MDR) region] was sequenced. Results: SGI1 was detected in 7 isolates; 5 out of the 57 isolates collected during the study period (9%) and 2 out of the 9 ESBL-producing strains of our collection. The structures of the seven SGI1s were distinct. Three different backbones were identified: one identical to the SGI1 backbone from the epidemic Salmonella Typhimurium DT104, one with variations already described in SGI1-K from Salmonella Kentucky (deletion and insertion of IS1359 in the region spanning from S005 to S009) and one with a variation never detected before (deletion from S005 to S009). Six different MDR regions were identified: four simple variants containing resistance genes already described and two variants harbouring a very complex structure including regions derived from several transposons and IS26 elements with aphA1a never reported to date in SGI1. Conclusions: SGI1 variants are widely distributed among P. mirabilis clinical strains and might spread to other commensal Enterobacteriaceae. This would become a serious public health problem. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.