A natural antioxidant commonly found in green tea could help boost the ability of antibiotics to fight infections caused by certain strains of bacteria that are becoming more resistant to current treatments, new research finds.

The compound, epigallocatechin (EGCG), can restore the efficacy of aztreonam, an antibacterial commonly used to treat infections caused by a bacterial pathogen Pseudomonas aeruginosa. P. aeruginosa causes a variety of ailments – from ear and blood infections to skin rashes – and is considered a “serious” global threat by world leaders

"The World Health Organisation has listed the antibiotic-resistant Pseudomonas aeruginosa as a critical threat to human health. We have shown that we can successfully eliminate such threats with the use of natural products, in combination with antibiotics already in use," said study co-author Roberto La Ragione, from the University of Surrey, in a statement.

Resistance makes bacteria stronger and more difficult to kill and has been observed in bacteria prevalent in both humans and wildlife populations. An estimated 51,000 infections in people who had recently been in a hospital or doctor’s office are reported in the US every year, more than 6,000 (13 percent) of which are resistant to multiple drugs, resulting in about 400 deaths every year.

To determine the effects of EGCG when used in combination with aztreonam, researchers conducted in vitro tests to see how the two interacted with P. aeruginosa both individually and when used in tandem. When used together, EGCG and aztreonam “significantly enhanced bacterial killing” than when used individually. Additionally, testing of the two in vivo with moth larvae confirmed those findings, while human skin cell tests show minimal-to-no toxicity.

The researchers believe that EGCG may help facilitate increased uptake of aztreonam by increasing permeability in the bacteria and could also interfere with a “biochemical pathway” linked to antibiotic susceptibility. Published in the Journal of Medical Microbiology, the findings could help inform how healthcare professionals combat antibiotic resistance.

"Antimicrobial resistance (AMR) is a serious threat to global public health. Without effective antibiotics, the success of medical treatments will be compromised. We urgently need to develop novel antibiotics in the fight against AMR,” said study author Jonathan Betts, from the University of Surrey, in a statement. “Natural products such as EGCG, used in combination with currently licensed antibiotics, may be a way of improving their effectiveness and clinically useful lifespan."

The study authors note that further developments of alternatives to antibiotics may be useful in future clinical settings.