A new study sheds light on how excessive usage of antimicrobials among livestock may threaten human immunity. It may do so by facilitating bacteria evolution until their strains become resistant to human immunity's first-line defenses.
Rise of Drug-Resistant Infections
One pressing and most serious threat that the world faces today is the rise of drug-resistant infections. Science Daily notes that, with this, the development of new and effective antimicrobials is urgent.
While several approaches are at work, one potential solution is antimicrobial peptides (AMPs). These are naturally made by the majority of living creatures and play vital roles in fostering immunity. Science Daily notes that they serve as the "first-line defense against bacterial infections."
The downside of things, however, is that AMPs are also utilized in livestock production. They serve as growth promoters and infection management.
Given this, concerns regarding agricultural AMP have been raised. These AMPs may lead to the generation of bacteria that are cross-resistant and that may potentially overpower the innate and first-line defense.
Antimicrobial Use Among Livestock
Now, a study led by the University of Oxford shows that the evolution of such resistant bacteria is very probable and not just possible.
To test their notions, the specialists made use of colistin, which is an AMP that a bacterium (Bacillus polymyxa) produces that is functionally and chemically similar to the AMPs that animals make. The researchers note in a statement that colistin is often referred to as the last-line defense for treating multidrug-resistant bacterial infections.
However, their extensive usage in livestock cultivation for the past four decades or so has fostered E.coli bacteria spreading. These bacteria harbor MCR, or mobile colistin resistance, genes.
As part of the study, E. coli got exposed to the AMPs that are acknowledged for playing vital roles in pig, chicken, and human immunity. The bacteria also were tested for their capacity to infect larvae of wax moths and susceptibility to human serums.
Their findings revealed that on average, the MCR-1 gene boosted resistance to innate AMPs by roughly 62%. This was in comparison to bacteria that did not have this gene.
At the same time, E. coli that carried the said gene had an at least doubled resistance to being eradicated by human serums.
Boosted virulence in wax moth larvae was also observed for E. coli that carried this gene. Larvae that were injected with this gene-filled E. coli had a roughly 50% less likelihood of survival.
Science Daily notes that such findings show that using AMPs for agricultural purposes may lead to cross-resistance to innate human immunity defense lines.
Potentially More Dangerous Than Antibiotic Resistance
The researchers note that cross-resistance may be widespread, considering the similar cellular targets and physico-chemical properties of AMPs.
WION adds that professor Craig MacLean, the study's lead researcher, explains how this could be more dangerous compared to antibiotic resistance. He notes how the study stresses how dangerous it is to indiscriminately use antimicrobials for agricultural purposes. Fatter chickens are being cultivated at the expense of human immunity.
AMPs have been seen to be promising antibiotic alternatives for treating resistant bacterial infections. However, the use of AMPs in such a manner will foster AMP resistance.
Professor MacLean also adds that such realities have serious implications on the use and design of therapeutic AMPs. Genes that are resistant could be hard to eradicate, even if agricultural use of AMPs is stopped.
He further stresses the need to properly cater to the effects of AMP-resistant virulencies before these are incorporated into patient treatment.
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