Colistin-resistance genes in Central Asia: a public-data gap map and a sequence-based screen of conserved mcr-1 target windows

Background. Colistin is a last-resort antibiotic. The mcr genes let bacteria resist it and pass that ability on through plasmids. Public genomic data from Central Asia are scarce, and a DNA or RNA test for mcr-1 needs targets that stay the same across variants but differ from related genes. Methods. NCBI Pathogen Detection metadata (2,967,802 isolates, downloaded 25 October 2026) were searched for genomes from Kazakhstan, Uzbekistan, Kyrgyzstan, Tajikistan and Turkmenistan, and the literature in PubMed, Europe PMC and CyberLeninka. On 29 October 2026 NCBI BioSample and Assembly were also searched for bacterial records from the same countries, and the 1,481 public assemblies found were screened for mcr genes. Thirty-seven mcr-1 alleles were aligned with Clustal Omega. Windows of 30 letters identical in every allele were compared, by counting differing letters, with 90 related alleles, 9,749 other resistance genes, 37 bacterial genomes, human RNA and DNA, real mcr-1 copies (246 GenBank records and 513 copies in public assemblies) and published primers. Results. None of the 286 Central Asian genomes (262 from Kazakhstan) had an mcr call, whereas 74 of 7,208 Russian genomes did, and no source searched reported mcr in the region. The 286 genomes are 5.5% of the 5,214 bacterial BioSamples with sequence data from the five countries. A screen of the 1,481 public assemblies found mcr-3-like chromosomal genes in two Aeromonas genomes (68 to 80% protein identity to the closest catalogued MCR protein); no other flagged gene was more than 53% identical. In mcr-1.1, 1,519 of 1,626 letters (93.4%) were identical in all 37 alleles. Four of five windows passed all five pass-or-fail lines. The best, at positions 118–147, differed from every relative in at least 12 of 30 letters and was identical in 244 of 244 GenBank records and 454 of 455 assembly copies. Conclusions. The public data cannot show whether mcr genes are present in Central Asia; they show how little is sequenced. The windows are predicted from sequence comparison only; no laboratory test was done. Keywords: colistin resistance; mcr-1; Central Asia; Kazakhstan; genomic surveillance; conserved target; sequence comparison