Survey of multidrug resistance integrative mobilizable elements SGI1 and PGI1 in Proteus mirabilis in humans and dogs in France, 2010-13.

Objectives: To characterize MDR genomic islands related to Salmonella genomic island 1 (SGI1) and Proteus genomic island 1 (PGI1) in Proteus mirabilis from human and animal sources in France in light of the previously reported cases.

Methods: A total of 52 and 46 P. mirabilis clinical strains from human and animal sources, respectively, were studied for the period 2010-13. MDR was assessed by antimicrobial susceptibility testing, PCR detection of SGI1 and PGI1 and PCR mapping of the MDR regions. The diversity of the SGI1/PGI1-positive P. mirabilis strains was assessed by PFGE.

Results: Twelve P. mirabilis strains (5 humans and 7 dogs) were found to harbour an MDR island related to SGI1 or PGI1. Among them, several SGI1 variants were identified in diverse P. mirabilis genetic backgrounds. The variant SGI1-V, which harbours the ESBL bla VEB-6 gene, was found in closely genetically related human and dog P. mirabilis strains. The recently described PGI1 element was also identified in human and dog strains. Finally, one strain harboured a novel SGI genomic island closely related to SGI1 and SGI2 without an insertion of the MDR region.

Conclusion: This study reports for the first time, to our knowledge, SGI1-positive and PGI1-positive P. mirabilis strains from dogs in France. The genetic diversity of the strains suggests several independent horizontal acquisitions of these MDR elements. The potential transmission of SGI1/PGI1-positive P. mirabilis strains between animals and humans is of public health concern, notably with regard to the spread of ESBL and carbapenemase genes, i.e. bla VEB-6 and bla NDM-1.