Letting Down Our Defences

Humans are proving pretty effective at damaging their own immune defences. The use of antibiotics as growth enhancers by farmers, enhances the development of resistant strains of bacteria. Fatter pigs and chickens means bigger profits! There's now evidence that the efficacy of Antimicrobial peptides (AMPs) is also being challenged in the same way (https://www.theguardian.com/society/2023/apr/25/use-of-antibiotics-in-farming-endangering-human-immune-system). AMPs are part of the body's innate first line of defence against micro-organisms. They are part of a system that 'kicks in', before the production of antibodies (the second line of defence). Like antibiotics, AMPs have been given by farmers to their animals. One AMP, Colistin was used from the 1980s on Chinese farms, to fatten pigs and chickens. Fortunately, it's now banned. These AMPs are similar, however, to those produced by the human immune system. A study published in the journal eLife has shown that using AMPs in farm animals, encourages the survival of resistant bacteria. E. coli , with the MCR-1 resistance gene increased in bacterial populations. The MCR-1 gene essentially creates a version of the bacterium that's likely to be resistant to human AMPs. Medicines are created and then commercial pressures often reduce their effectiveness. Like antibiotics, AMPs should be used, only where appropriate. Overuse always reduces effectiveness.