Colistin Drug Resistant Determinant Mcr-1 Gene Spreads in Conjugative Plasmids Creating Huge Confusion for the Treatment of Multi-Drug Resistant Infections
Post Graduate Department of Biotechnology & Biochemistry, OIST, Vidyasagar University, West Bengal Midnapore-India.
Citation: Asit Kumar Chakraborty, “ Colistin Drug Resistant Determinant Mcr-1 Gene Spreads in Conjugative Plasmids
Creating Huge Confusion for the Treatment of Multi-Drug Resistant Infections”, American Research Journal of
Biotechnology, Vol 1, no. 1, 2022, pp. 1-6.
Abstract
Worldwide spread of new MDR gene, Phosphoethanolamine –Lipid A transferase (Mcr-1) in superbug plasmids has
threatened the treatment options of multi-drug resistant infections. Colistin is higher derivative of polymyxin that
facilitates cell-membrane leakage in bacteria after binding to the membrane phospholipids. The Mcr-1 enzyme actively
transfer phosphoethanolamine to membrane phospholipid-A inhibiting the asses of colistin to bind on membrane to
exert its toxicity. Colistin is very active against MDR bacteria with plasmids borne or chromosomal-mediated blaTEM,
blaCTX-M, blaOXA, catB3, strA/B, sul1/2, aacA1, aacC1, aadA2 and aphA4 mdr genes as well as many drug efflux genes.
Although Mcr-1 gene discovered in 2015 in China but already had identified in most continents with many mutations
(Mcr-1.1 to Mcr-1.8) and different isoforms (Mcr-2.1, Mcr-2.2, Mcr-3.1, and Mcr-4.1 ). TheMcr-1 plasmids are small 33kb
with no other mdr gene but 60kb Mcr-1 plasmids have CTX-M, aadA2, arr3 types mdr genes. Very recently discovered high
molecular weight (>200kb) conjugative plasmids however, have 4-6 mdr genes with one dozen metal drug resistant genes.
Un-noticed deaths by NDM-1, MCR-1, CTX-M-15, MecA, VanA, AAC6’-1b-cr and OXA-23 superbugs are highly occurring in
poor nations. Sadly, superbugs have greatly activated by acquiring 6-12 mdr genes during sexual conjugation and also
mobilizing mdr genes into chromosome as well as target specific mutations of rRNA and porin genes. Thus development
of alternative medicines like gene medicines (Antisense, Crisper-Cas, miRNA, SiRNA, Ribozymes), phyto-antibiotics and
nano-drug carriers is urgent need to stop huge loss of life and wealth worldwide. G-20 Nations were gathered at Berlin
(May 2017) and Hamburg (July 2017) and issued action plans to stop superbug horror.
