Co-occurrence of mcr-2 and mcr-3 genes on chromosome of multidrug-resistant Escherichia coli isolated from healthy individuals in Thailand

•Three different sequence types (STs) of Escherichia coli harboring mcr genes including ST165, ST1602, and ST34 were isolated from healthy individuals.•Co-occurrence of plasmid derived mcr-1 and chromosomal mcr-3 was found in E. coli ST34.•Co-occurrence of mcr-2 and mcr-3 on E. coli chromosome was first reported.•Novel mobile genetic element (MGE) harboring mcr-2 integrated into the chromosome by phage integrase was first discovered.