Genomic insights into multidrug-resistant bacteria: Emergence of mcr-1.1 in Escherichia coli, blaKPC-2 in Klebsiella pneumoniae and Serratia marcescens from clinical settings.

This study presents a comprehensive genomic analysis of multidrug-resistant (MDR) clinical isolates from Anhui Province, China, focusing on Escherichia coli, Klebsiella pneumoniae, and Serratia marcescens. The E. coli strain EC385 belong to ST1011 and rST1640 harbors multiple resistance and virulence determinants and five plasmids, including IncI2 and IncHI2, with a co-occurrence of mcr-1.1 with blaTEM-141, qnrS1, fosA3, rmtB, and dfrA14. Among K. pneumoniae isolates, KP304 (ST15/rST19202) and KP297 (ST15/rST19202) were carrying IncFII(pBK30683) and IncFIB plasmids, while KP69 (ST11/rST31218) harbored five plasmids, including IncHI1B and IncR. Notably, KP304, KP297, and KP69 exhibited MDR due to acquisition of blaKPC-2 along with other multiple resistance determinants including fosA6, tet(A), blaTEM-1B, blaCTX-M, aac(6)-Ib-cr (KP304 and KP297), and qnrS1 (KP69). In the current finding, S. marcescens is reported to carry blaKPC-2, alongside IncFII(pBK30683) and IncR plasmids. These findings highlight the genomic diversity and alarming spread of resistance mechanisms in clinical pathogens, emphasizing the urgent need for surveillance to combat the antimicrobial resistance.