Retrospective Analysis of Mobile Colistin Resistance and Plasmid-Mediated Quinolone Resistance Genes in Escherichia coli: China, 1993-2019

Plasmid-mediated quinolone resistance (PMQR) genes and mobile colistin resistance (MCR) genes in Escherichia coli (E. coli) have shown an increasing prevalence in recent years. This rise is particularly notable in China and several Southeast Asian countries, representing a significant threat to public health. In the present study, we conducted a retrospective analysis of MCR genes (mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5) and PMQR genes (qnrA, qnrB, qnrC, qnrD, qnrE1, qnrVC, qnrS, aac(6)-Ib-cr, qepA, and oqxAB). From the 3,663 E. coli isolates examined, 1,613 (44.0%) tested positive for PMQR genes, either individually or in combination. Meanwhile, 262 isolates (7.0%) carried MCR genes. Minimum inhibitory concentration (MIC) analyses of 17 antibiotics for the MCR gene-carrying strains revealed universal multidrug resistance. Resistance to polymyxin varied between 4 g/mL and 64 g/mL, with MIC50 and MIC90 values at 8 g/mL and 16 g/mL, respectively. Additionally, fluctuations in the detection rates of these resistant genes correlated with the introduction of antibiotic policies, host origin, temporal trends, and geographical distribution. IMPORTANCEAntimicrobial resistance (AMR) has emerged as a threat to global health and development, and E. coli resistance remains an ongoing clinical challenge. However, the efficacy of colistin and quinolones has been compromised by the presence of various MCR and PMQR genes. To elucidate the prevalence and distribution of MCR and PMQR genes in E. coli isolates, we analyzed 3,663 E. coli isolates from 29 provinces in China from 1993 to 2019. The results show that 1,613 (44.0%) tested positive for PMQR genes, 262 isolates (7.0%) carried MCR genes. And MICs analyses of 17 antibiotics for the MCR gene-carrying strains revealed universal multidrug resistance. These indicated prohibiting or strictly curtailing antimicrobial use in animal or human is urgently needed to reduce the growing threat from AMR.