Scientists have cautioned that the widespread use of antibiotics in agriculture has resulted in the creation of germs that are more resilient to the human immune system.

The research implies that the rise of E.coli strains that are more likely to elude the human immune system's first line of defense was caused by the antibiotic colistin, which was used for decades as a growth promoter on pig and poultry farms in China.

Despite the fact that colistin is already prohibited in China and many other nations as a livestock food additive, the research raises concerns about a fresh and serious hazard posed by the abuse of antibiotics.

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Prof. Craig MacLean, who oversaw the research at the University of Oxford, said that colistin might be considerably more harmful than antibiotic resistance, and emphasized the peril of using antimicrobials in agriculture carelessly. MacLean believes that in order to make hens bigger, we unintentionally compromised our own immune systems.

The discoveries may also have important ramifications for the creation of novel antimicrobial peptides (AMPs), a class of antibiotics that includes colistin and which the researchers believe may offer a special danger of undermining innate immunity.

The majority of living things make AMPs as part of their innate immune response, which is their first line of defense against infection. Colistin is based on a bacterial AMP, which germs employ to protect themselves against rivals, but it has certain chemical properties with other AMPs made by the human immune system.

Since the 1980s, when colistin was widely used in cattle, colistin-resistant E.coli bacteria have been on the rise. This has led to significant limits on the drug's usage in agriculture. However, the most recent research indicates that the same genes may also make it easier for infections to avoid AMPs, which are essential to our own immune response.

The researchers discovered that MCR-1-positive E. coli had at least two times the resistance to being killed by human serum. When compared to bacteria that lacked the gene, the resistance to human and animal AMPs rose by an average of 62%. The research, which was written up in the journal eLife, also revealed that the resistant E.coli was twice as likely to infect and kill moth larvae when compared to the control E.coli strain.

According to MacLean, it is impossible to predict the effects this would have in the real world. And since China outlawed the use of colistin as a growth promoter, the predominance of these strains of E.coli has sharply decreased, indicating that these genes may have additional "fitness disadvantages" for the pathogens. The results, however, draw attention to a crucial danger that hasn't been fully taken into account.

Deadly superbugs

The risk, according to MacLean, is that if bacteria develop resistance to [AMP-based treatments], they may also develop resistance to a key component of the human immune system.

While MacLean and colleagues do not advocate for halting the development of these medications, they do argue that very rigorous risk evaluations of the chance of resistance developing and any potential repercussions are necessary. There might be some extremely substantial negative effects for AMPs, he noted.

According to Dr. Jessica Blair from Birmingham University, “Antimicrobial peptides, including colistin, have been heralded as a potential part of the solution to the rise of multidrug-resistant infections. This study, however, suggests that resistance to these antimicrobials may have unintended consequences on the ability of pathogens to cause infection and survive within the host.”

Dr. George Tegos of the Mohawk Valley Health System in New York stated that general conclusions regarding the possible hazards of AMPs could not be taken from a single research, but added that the results "raise concerns that are reasonable and make sense".

This new study demonstrates that colistin resistance is likely far more hazardous than previously believed, according to Coiln Nunan, a consultant for the Alliance to Save Our Antibiotics who was not involved in the study. The British government's continued opposition to the EU's prohibition on the widespread use of antibiotics for prophylactic purposes in intensive livestock farming is also noteworthy.