New research highlights how dietary zinc could slow the transmission of antimicrobial resistance (AMR) genes in the gut.
Antimicrobial resistance poses a significant threat to global health, with millions of infections diagnosed each year, resulting in 35,000 deaths annually in the US alone.
A new study sheds light on a potential solution to help slow the spread of AMR genes—dietary zinc supplements.
Zinc supplements disrupt AMR gene transfer
Researchers at Iowa State University have discovered that zinc may play an essential role in inhibiting the transmission of AMR genes through plasmids, circular pieces of genetic material that bacteria use to exchange genetic information.
This exchange, known as horizontal gene transfer, typically occurs in the gut and allows bacteria to acquire resistance to multiple drugs.
Lead microbiologist and senior author of the study, Melha Mellata, PhD, emphasised the importance of this discovery.
“This is the first time where we’ve discovered that zinc inhibits the process of plasmid transfer, and at lower concentrations, it has minimal effect on bacteria,” Mellata explained.
This finding is crucial because destroying gut bacteria can negatively impact the microbiome, leading to various health issues.
By inhibiting plasmid transfer rather than killing the bacteria, the spread of AMR genes can be controlled without disturbing the delicate balance of microorganisms in the gut.
AMR: A growing health threat
The rise of AMR genes is becoming an increasing concern in the medical community. When bacteria acquire AMR genes, they can become resistant to several antibiotics before a person even begins treatment. This resistance makes infections more difficult to treat and can lead to more severe outcomes.
Mellata’s lab has been exploring the connections between gut health and overall health, which led to the discovery of zinc’s potential in halting the spread of AMR genes.
Previous research conducted by her team found that chickens treated with probiotics and a live Salmonella vaccine had fewer plasmids in their gut bacteria.
This observation inspired them to explore other ways to reduce plasmid transmission, particularly through dietary interventions.
Zinc’s surprising impact
To test zinc’s effects, Logan Ott, a researcher in Mellata’s lab, conducted experiments in which avian pathogenic Escherichia coli (E. coli) containing multi-drug resistant plasmids interacted with a plasmid-free human E. coli isolate.
Zinc supplementation was added to the bacterial strains, and the results were striking—plasmid transfer rates dropped significantly compared to bacterial strains without zinc.
Interestingly, higher concentrations of zinc further reduced the levels of plasmid transfer, a discovery that surprised researchers.
Previous studies had shown that heavy metals like zinc could actually promote plasmid transfer, but Mellata’s team found that zinc triggered overexpression of replication genes.
This caused an overload, ultimately inhibiting the process of plasmid transfer. Additionally, zinc appeared to block specific proteins necessary for building the structures bacteria use to transfer plasmids.
Testing zinc’s efficacy on other genes
While the initial findings are promising, Mellata and her team aim to expand their research to other AMR genes and animal models. Testing zinc’s impact in vivo will provide crucial insights into whether these results can be replicated in living organisms.
The study also opens the door to further exploration of how gut bacteria interact and share AMR genes, an area that remains poorly understood. Future research could help uncover more about the mechanisms behind bacterial conjugation and the role that zinc, and potentially other readily available supplements, could play in slowing down the spread of AMR genes.
A new tool in the fight against AMR
The discovery that dietary zinc can inhibit the transfer of AMR genes through plasmids presents a new avenue for combating the spread of drug-resistant infections.
As researchers continue to investigate the effects of zinc and other dietary supplements, this study offers hope that easily accessible solutions could make a significant impact in the ongoing battle against antimicrobial resistance.
