Sequencing and Analysis of pmrA and pmrB Genes

The coding sequences of the pmrA and pmrB genes in E. coli and K. pneumoniae were amplified as previously described by Jayol et al. (2014) (link), Quesada et al. (2015) (link), and Haeili et al. (2017) (link). PCR amplicons were purified using the innuPREP DOUBLEpure Kit (Analytik Jena AG, Jena, Germany) and sequenced at Microsynth Seqlab (Göttingen, Germany). Genomic DNA from five randomly selected mcr-1-negative colistin-susceptible E. coli and K. pneumoniae isolates (colistin MIC < 2 mg/L) originating from the same samples were used as control. Sequence analysis was conducted with Chromas lite v.2.6.5 (Technelysium Pty. Ltd.) and BioEdit v.7.2.5 (Hall, 1999 ).