Bacteria resistant to colistin antibiotics - a last resort treatment in human medicine - have been detected in the United States.

Colistin resistant bacteria were first detected in 2015 in China, where the antibiotic class is widely used in animal agriculture. The bugs were detected in a number of European countries later the same month. The scientists who discovered the resistance in China said there is a strong link between its development and the use of crucial antibiotics on farms.

Resistant bacteria were discovered in the United States when a Pennsylvania woman’s E.Coli infection was found to be untreatable with colistin. A paper detailing the discovery was published in a journal of the American Society for Microbiology on Thursday. The authors warned that this "heralds the emergence of a truly pan-drug resistant bacteria.”

The US Centers for Disease Control and Prevention (CDC) announced it is launching a “coordinated public health response,” in Pennsylvania in order to prevent the spread of the resistant bug.

Colistin is only used as a last line of defence in human medicine, as it carries serious side effects, and is therefore used only when other treatments have failed.

What makes colistin resistance more alarming is that the gene conferring resistance is easily passed between bacteria species. The researchers who first identified the resistant gene found it in a family of bacteria that contains E.Coli, Salmonella, Klesbsiella pneumoniae (which can cause pneumonia and a variety of other infections) and Yersinia pestis (bubonic plague).

The discovery in Pennsylvania was made as the EU’s medicines regulator - the European Medicine Agency (EMA) - and UK Prime Minister David Cameron came under fire over proposals to limit the use of colistins in agriculture, which campaigners do not think go far enough. Responding to proposals from the UK government and EMA earlier in the week, Cóilín Nunan, scientific adviser to the Alliance to Save our Antibiotics said, “The European Medicine Agency is being grossly irresponsible and putting people’s lives at risk by supporting the mass medication of farm animals with a last-resort human antibiotic.

“We believe that the targets announced by Mr Cameron are not nearly ambitious enough as it would only require a relatively small reduction from current levels… if the Prime Minister is serious about protecting critically important antibiotics, he must immediately ban the use of colistin in farm animals.”
 
Campaigners said regulators are failing to meet recommendations set out in the UK government-commissioned O’Neill Review on Antimicrobial Resistance, which was published in full earlier this month. The review sets out a number of recommendations for action to avoid entering a ‘post-antibiotic age’ in which antibiotic resistant bacteria kill one person every three seconds - this could become reality by 2050, according to the review. Lord Jim O’Neill, who chaired the review, called for incentives to develop new antibiotics, improved diagnostics and vaccines, and country-specific targets for reducing antimicrobial use in livestock (including a ban on last resort treatments in animal agriculture).