Wastewater as a Breeding Ground for Antibiotic Resistance: Natural Compounds Offer Potential Solution
A growing threat to global public health, antibiotic resistance is increasingly linked to the presence of multi-drug resistant bacteria in wastewater, according to new research published in Frontiers in Microbiology in July 2025. Scientists have identified concerning strains capable of withstanding multiple classes of antibiotics in a wastewater treatment facility in Logan, Utah, raising fears about the potential for these genes to transfer to more dangerous pathogens.
The Rising Tide of Antibiotic Resistance
Antibiotic resistance occurs when bacteria evolve to survive exposure to drugs designed to kill them or halt their growth. This adaptation is accelerated when bacteria encounter sub-lethal doses of antibiotics – a common occurrence as medications are processed by the human body and released into wastewater systems through urine and feces. Wastewater treatment plants, while designed to purify water, can inadvertently become environments where these resistant bacteria thrive.
Utah Study Reveals Troubling Findings
Researchers at Utah State University screened wastewater samples for strains resistant to sulfamethoxazole, identifying nine strains exhibiting resistance to several antibiotic classes. One strain, designated U2, demonstrated resistance to all drugs tested, including colistin, a critical “last-resort” antibiotic. “Without improved treatment, wastewater could serve as a breeding ground for ‘superbugs’ that may enter water resources such as rivers, lakes, and reservoirs, posing potential risks to public health,” warned Dr. Liyuan ‘Joanna’ Hou, lead researcher on the project.
The identified strains belonged to species including Microbacterium, Chryseobacterium, Lactococcus lactis, and Psychrobacter. While generally not harmful to healthy individuals, these bacteria can cause illness in those with compromised immune systems and, crucially, can act as reservoirs for resistance genes that could transfer to more virulent bacteria like Escherichia coli.
Harnessing Nature’s Pharmacy
To explore potential solutions, the research team investigated the effectiveness of 11 natural compounds known for their antimicrobial or anti-biofilm activity. A biofilm is a structured community of bacteria that grows on surfaces and produces a protective layer, making them more resistant to treatment. Among those tested, curcumin – a compound found in turmeric – and emodin – found in rhubarb – showed the most promise in limiting the growth and activity of the antibiotic-resistant strains.
Promising Results, But Further Research Needed
The study revealed that curcumin reduced bacterial cell activity, inhibited growth, and disrupted biofilm development. Emodin, particularly at higher concentrations, also suppressed bacterial activity, although lower concentrations unexpectedly stimulated some strains. However, Gram-negative bacteria, such as Chryseobacterium, proved unaffected by any of the tested compounds.
Gram-negative and Gram-positive bacteria are classified based on differences in their cell walls. Gram-negative bacteria possess an additional outer membrane, making them generally more resistant to antibiotics, while Gram-positive bacteria are often more susceptible. These initial findings suggest that plant-derived compounds may be particularly effective against Gram-positive strains in wastewater.
Despite these encouraging results, researchers emphasize the need for further investigation. Future studies must evaluate the performance of these compounds in complex, real-world wastewater environments, assess their compatibility with existing treatment methods, and determine their long-term impact on microbial populations. .
The research was published under the following citation: Li M, Zhan A, Rahman TT, Jiang T, Hou L. From wastewater to resistance: characterization of multidrug-resistant bacteria and assessment of natural antimicrobial compounds. Front Microbiol. 2025;16. doi: 10.3389/fmicb.2025.1612534. This article has been republished from original materials and may have been edited for length and content.
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