Colistin was regarded as the antibiotic of last resort as resistance to all the others had developed in various bacteria. That is no longer the case.
Chinese scientists identified a new mutation, dubbed the MCR-1 gene, that prevented colistin from killing bacteria.
The report in the Lancet Infectious Diseases showed resistance in a fifth of animals tested, 15% of raw meat samples and in 16 patients. And the resistance had spread between a range of bacterial strains and species, including E. coli, Klebsiella pneumoniae and Pseudomonas aeruginosa.
There is also evidence that it has spread to Laos and Malaysia.
Unlike previous resistance to Colistin, this mutation is very easily transmitted to other bacteria. The development has been put down to the over-use of the antibiotic by farmers. Professor Timothy Walsh of Cardiff University who collaborated on the study told the BBC:
All the key players are now in place to make the post-antibiotic world a reality. If MRC-1 becomes global, which is a case of when not if, and the gene aligns itself with other antibiotic resistance genes, which is inevitable, then we will have very likely reached the start of the post-antibiotic era.
Unless new families of antibiotics are developed, a likely outcome could be that by 2050, over 4 million deaths from antibiotic resistant diseases every year will occur in both Africa and Asia. Europe, North America and South America could each see over 300,000 deaths every year.