Colistin Resistance Mediated by -Related Phosphoethanolamine Transferase Genes in Species Isolated from Aquatic Environments in Avaga and Pakro Communities in the Eastern Region of Ghana.

Purpose: Colistin is classified by the World Health Organization (WHO) as a critically important and last-resort antibiotic for the treatment of infections caused by carbapenem-resistant bacteria. However, colistin resistance mediated by chromosomal mutations or plasmid-linked mobilized colistin resistance () genes has emerged.

Methods: Thirteen -positive species isolated from water samples collected in Eastern Ghana were analyzed using whole-genome sequencing (WGS). Antimicrobial susceptibility was tested using the broth microdilution method. Resistome analysis was performed using a web-based platform.

Results: The minimum inhibitory concentration (MIC) of colistin for all except three isolates was >4 µg/mL. Nine new sequence types were identified and whole-genome analysis revealed that the isolates harbored genes (-related genes) that code for Lipid A phosphoethanolamine transferases on their chromosomes. BLAST analysis indicated that the amino acid sequences of the -related genes detected varied from those previously reported and shared 79.04-99.86% nucleotide sequence identity with publicly available variants and -related phosphoethanolamine transferases. Analysis of the genetic context of -related genes revealed that the genetic environment surrounding -related genes was diverse among the different species of but conserved among isolates of the same species. -related-gene-IS--related-gene segment was identified in three strains.

Conclusion: The presence of -related genes close to insertion elements is important for continuous monitoring to better understand how to control the mobilization and dissemination of antibiotic resistance genes.