Isolation of four carbapenem-resistant gram-negative species from a single fly

The widespread occurrence of carbapenem-resistant organisms has garnered significant public attention. Arthropods, including flies, are important vectors of multidrug-resistant bacteria. In this study, we reported the simultaneous carriage of four carbapenem-resistant isolates from different species, namely, Escherichia coli ( E. coli ), Providencia manganoxydans ( P. manganoxydan ), Myroides odoratimimus ( M. odoratimimus ) and Proteus mirabilis ( P. mirabilis ), from a single fly in China. These isolates were characterized through antimicrobial susceptibility testing, conjugation assays, whole-genome sequencing, and bioinformatics analysis. M. odoratimimus showed intrinsic resistance to carbapenems. The mechanisms of carbapenem resistance in E. coli , P. manganoxydans , and P. mirabilis were due to the production of NDM-5, NDM-1 and NDM-1, respectively. Genetic context of the bla NDM genes in these three isolates varied. The bla NDM-5 gene in E. coli was located on an IncHI2/HI2A multidrug-resistant plasmid, which was conjugatively transferable. The bla NDM-1 gene in P. mirabilis resided on the pPM14-NDM_123k-like nonconjugative plasmid. The bla NDM-1 gene in P. manganoxydans was found in a nonconjugatively transferable, multidrug-resistant region. The results of this study enhance our understanding of the dissemination of carbapenem-resistant organisms and suggest the need for a more comprehensive approach to antibiotic resistance research encompassing humans, animals, and the environment.