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.

Two Novel Salmonella Genomic Island 1 Variants in Proteus mirabilis Isolates from Swine Farms in China

“…A few variations in the SGI1 backbone are also described due to deletion, insertion, and transposition (3,9,10,(12)(13)(14)(15). Furthermore, several novel resistance genes, including the extended-spectrum ␤-lactamase (ESBL) gene bla VEB-6 and the fluoroquinolone resistance genes qnrA1 and qnrB2, have been reported in SGI1 (9, 11), suggesting that SGI1 could act as a mobilizable element to disseminate the critical resistance genes.…”

“…Many SGI1 variants result from the homologous recombination of gene cassettes within the MDR regions (3,(8)(9)(10)(11). A few variations in the SGI1 backbone are also described due to deletion, insertion, and transposition (3,9,10,(12)(13)(14)(15).…”

Molecular Characteristics of Salmonella Genomic Island 1 in Proteus mirabilis Isolates from Poultry Farms in China

“…In 2007, SGI1-L was detected in a P. mirabilis clinical isolate, first confirming SGI1 was present in a genus other than Salmonella (7). Some novel SGI1 variants have been recently described in P. mirabilis (8)(9)(10)(11). Three studies have reported that SGI1-containing P. mirabilis could disseminate through meat food consumption, which poses a threat to public health (8,9,12), suggesting that SGI1-containing P. mirabilis clinical isolates might partly come from food-producing animals.…”

“…The complete SGI1 structures (backbone and MDR region) were established by PCR linkage and sequencing using primers listed in Table S1 in the supplemental material (11). Through PCR mapping, the complete nucleotide sequences of the six SGI1s ranged from 33.2 to 42.5 kb.…”

Scientific Opinion on the evaluation of molecular typing methods for major food‐borne microbiological hazards and their use for attribution modelling, outbreak investigation and scanning surveillance: Part 1 (evaluation of methods and applications)

“…Salmonella bacteriophages are often involved and mediate horizontal transfer of virulence genes among Salmonella strains by transduction and lysogenic conversion (Rabsch et al, 2002b). Integrons, genomic islands and plasmids (which may carry integrons with them) may be involved in transfer of bacterial secretion systems, virulence and antimicrobial resistance genes (Guerra et al, 2001;Dobrindt et al, 2004;Randall et al, 2004;Sandvang et al, 2006, Bhatty et al, 2013) from other organisms to Salmonella, and vice versa (Siebor and Neuwirth, 2013). …”