UTI: Cranberry juice may boost the effectiveness of antibiotics

Urinary tract infections affect more than 400 million people every year. More than half of all women will develop a UTI at least once in their lifetime. Most UTIs are caused by pathogenic strains of Escherichia coli bacteria. Fosfomycin, an antibiotic, is often the first line of defence against UTIs. However, rising antibiotic resistance is becoming a concern.

Researchers at the American Society for Microbiology may have found a solution to this problem. The findings of their new study suggest that cranberry juice may improve the effectiveness of antibiotics, at least in lab-grown strains. The findings are published in Applied and Environmental Microbiology.

The role of cranberry juice

Cranberry juice has long been regarded as a folk remedy for preventing and treating urinary tract infections. However, scientists thought the benefit might come from its high acidity. Recent studies have linked its effect to compounds in the juice that can block bacteria from attaching to cells lining the urethra. However, until now, researchers had not examined cranberry juice’s interactions with antibiotics.



In the paper, the researchers explained how cranberry juice interacts with fosfomycin and bacteria. Fosfomycin enters bacterial cells through the same entry channels used by microbes to acquire certain sugars. According to Déziel, something in cranberry juice induces the bacteria to increase their uptake of sugars through one of those channels, which means they also absorb more fosfomycin. However, scientists are not yet sure what this substance is. Resistance to antibiotics often results from mutations in these same nutrient pathways.

Study shows promising results

The researchers found that in 72% of the E. coli strains tested, cranberry juice enhanced the antibiotic’s activity. This also suppressed the emergence of mutations related to resistance. The lead author and microbiologist Eric Déziel, PhD, at the Institut National de la Recherche Scientifique in Montreal, Canada, noted, however, that the work is promising but preliminary.

The study also does not show whether the same benefits exist after consumption. “We don’t know if the metabolites will reach the infection,” Déziel said. If they do, this could certainly increase the efficiency of antibiotic treatment. However, further studies are required to determine how much cranberry juice would confer any benefit.

Déziel’s lab studies how bacteria communicate and looks for natural substances that can disrupt this process to help treat infections. In earlier lab research, his team found that cranberry extracts could make antibiotics work better against resistant bacteria. These results drew interest from the Cranberry Institute. They wanted to know whether cranberry juice had the same effect on bacteria as cranberry extracts. “It’s a very good question. People actually drink juice. They don’t consume these very specific extracts,” Déziel said.

Déziel emphasised that while the findings show promise, this study does not establish a connection between drinking juice and antibiotic potency. The study, however, supports the idea that natural compounds may be a useful frontier in fighting antibiotic resistance. “With the challenge of multi-drug resistance, we need to work from many different directions,” Déziel said.