Plasmid-Mediated Co-Occurrence of mcr-1.1 in Extended-Spectrum β-Lactamase (ESBL)-Producing Escherichia coli Isolated From the Indigenous Seminomadic Community in Malaysia.

The growing prevalence of commensal antibiotic resistant Escherichia coli poses a significant concern for the global spread of antibiotic resistance. Stool samples (n = 35) from a seminomadic indigenous community in Malaysia, the Jehai, were screened for multidrug-resistant bacteria, specifically the extended-spectrum β-lactamase (ESBL) producers. Subsequently, whole-genome sequencing was used to provide genomic insights into eight ESBL-producing E. coli that colonised eight individuals. The ESBL E. coli isolates carry resistance genes from various antibiotic classes such as the β-lactams (bla TEM, bla CTX-M-15 and bla CTX-M-55), quinolones (gyrA, qnrS and qnrS1) and aminoglycosides (aph(3')-Ia, aph(6)-Id and aac(3)-IId). Three concerning convergence of ESBL, colistin and metal resistance determinants, with three plasmids from H-type lineage harbouring bla CTX-M and mcr-1.1 genes were identified. Using the Oxford Nanopore Technology (ONT) Native Barcoding Kit (SQK-NBD114.24) in conjunction with the R10.4.1 flow cell, which achieved an average read accuracy (Q > 10) of 99.84%, we further characterised the mcr-1.1-bearing plasmids, ranging in size from 25 to 28 kb, from three strains of E. coli. This report represents the first whole genome analysis of multidrug-resistant bacteria, specifically those resistant to colistin, found within the indigenous population in Malaysia. It strongly indicates that the pertinent issue of colistin resistance in the country is far more significant than previously estimated.