Genetic characterization and virulence of a carbapenem-resistant Raoultella ornithinolytica isolated from well water carrying a novel megaplasmid containing blaNDM-1.

Infections caused by carbapenem-resistant Enterobacteriaceae are a growing concern worldwide. Raoultella ornithinolytica is a species in the Enterobacteriaceae family which can cause hospital-acquired infections and is sporadically reported as carbapenem-resistant from human and environmental sources. In this study, we firstly report on an NDM-1-producing R. ornithinolytica , Rao166, isolated from drinking water in an animal cultivation area in China. In addition to carbapenem-resistance, Rao166 was resistant to several other antibiotics including gentamicin, sulfamethoxazole-trimethoprim, tetracycline and fosfomycin. Rao166 carried a novel IncFIC-type megaplasmid, 382,325 bp in length (pRAO166a). A multidrug resistance region, 60,600 bp in length, was identified in the plasmid containing an aac(3)- IId-like gene, aac(6′)- Ib-cr, bla DHA-1 , bla TEM-1B , bla CTX-M-3 , bla OXA-1 , bla NDM-1 , qnrB4 , catB3 , arr-3 , sul1 , and tet(D). Results from virulence assays implied that Rao166 has considerable pathogenic potential. Although pRAO166a was found to be non-transmissible, dissemination of the NDM-1 producing strain may occur from well water to humans or animals through cross-contamination during food preparation or directly via drinking water, and potentially lead to difficult-to-treat infections. Thus, contamination of well water by this carbapenem-resistant and presumptively virulent strain of R. ornithinolytica should be considered a potential public health risk. Image 1 • This is the first report of NDM-producing R. ornithinolytica in the environment. • A novel megaplasmid containing diverse ARGs and integrons was identified. • The isolate showed considerable virulence potential in in vivo infection assays. • Presence of pathogenic R. ornithinolytica in well water posed the public threat. Novel blaNDM-1-containing megaplasmid in a potentially virulent Raoultella ornithinolytica isolated from well water in rural China. [ABSTRACT FROM AUTHOR]