A 49 year old woman from Pennsylvania was recently hospitalised with an infection that the last resort antibiotic Colistin was unable to treat. Researchers studied a sample of her urine and found that the bacteria were carrying a gene called MCR-1, which confers resistance to Colistin.
Colistin was largely phased out in the 1970s due to its harsh side-effects, but in the face of increased antibacterial resistance it has once again found favour. Because resistance to Colistin is generally thought to be extremely rare, doctors often turn to it when all other antibiotics have proven to be ineffective.
MCR-1 was first identified in a swine infection in China in late 2015. MCR-1 is plasmid-borne, which means it can transfer onto different types of bacteria with ease. Healthcare professionals were keen to monitor its spread and have been scouring through samples for any sign. It has already been located in the UK, Africa, South America, parts of Asia, and now the USA.
The fear is that MCR-1 will align with other genes for resistance and spread to other types of bacteria, greatly exacerbating the rate at which resistance is spreading. This would also herald the beginning of the post-antibiotic era.
Because resistance develops naturally, we cannot actually stop it. The best we can do is mitigate its effects by using antibiotics efficaciously, and develop new ones faster than old ones become obsolete. Neither of these things are happening at the moment, and the MCR-1 case highlights just how quickly we are hurtling towards an ‘antibiotic apocalypse’.
The future of antibiotic use will have to be very different if we are to avert the worst of what has been dubbed ‘a clearer threat than climate change in the short term’. Fortunately, a global response is beginning to take shape. An expansive, in-depth report was recently published that outlined a ten-point plan to curb antimicrobial resistance (a blanket term for resistance to treatments for bacteria, parasites, fungi and viruses). It estimated that the costs of doing nothing were up to $100 trillion, and ten million lives.
In the UK, it is estimated that 1 in 4 antibiotic prescriptions are written unnecessarily, in cases where there is not a clear medical need. This is due largely to ‘pushy patients’ on one hand, and a lack of a reliable point-of-care diagnostic test for determining whether antibiotics are needed on the other. The Longitude Prize has set aside £10 million to reward the invention of a suitable test. Researchers have also developed a new type of dressing that changes colour when a wound becomes infected, to prevent unnecessary precautionary use of antibiotics.
Innovations are also shaping up on the supply-side. Recent research has pointed to both the human nose and a novel underground ‘soil hotel’ as potential sources of new antibiotics. The frequency of new discoveries has stagnated in the past forty years, as isolation becomes increasingly difficult and expensive, resulting in less R+D funding allocated by pharmaceutical companies.
The fact that MCR-1 was first identified on a farm draws attention to the role of the farm in spreading resistance. Antibiotics are used to fatten livestock and increase profits – presumably leading some to deny the links to antibacterial resistance. However, others have embraced the tide of change, with a trademark having recently been registered for ‘antibiotic free’ pork.