Rainforest plant combats bacterial strains

20 February 2012

A Danish scientist has identified a plant that could be effective in combating multi-resistant bacterial strains, such as those found in hospitals. A substance, which occurs naturally in a Chilean rainforest plant, could be used to supplement traditional antibiotic treatments.

Yellow staphylococcus (Staphylococcus aureus) is the most common cause of infection following hospital operations. The bacteria can cause a wide range of diseases, from abscesses and food poisoning to life-threatening infections such as infective endocarditis and sepsis.

The University of Copenhagen's Dr Jes Gitz Holler, whose results were published in the Journal of Antimicrobial Chemotherapy, gathered specimens of the plant from Chile, where the Mapuche people use its leaves to heal wounds.

The rate at which yellow staphylococci can develop resistance is extremely rapid, and bacterial strains that do not respond to treatments have already been found in the United States and Greece. The newly identified compound, however, targets a specific resistance mechanism in yellow staphylococci.

"I have discovered a natural substance in a Chilean avocado plant that is active in combination treatment with traditional antibiotics," said Dr Holler. "Resistant bacteria have an efflux pump in their bacterial membrane that efficiently pumps out antibiotics as soon as they have gained access. The identified natural substance inhibits the pumping action, so that the bacteria's defence mechanisms are broken down and the antibiotic treatment allowed to work."

The Minimum Inhibitory Concentration (MIC) value is the lowest possible concentration of an antibiotic that inhibits bacterial growth. The compound identified by Dr Holler is capable of lowering the MIC value by at least eight times. Dr Holler is confident that it will be possible to exploit the plant's attributes whilst protecting natural resources.

"The natural compound has great potential and perhaps in the longer term can be developed into an effective drug to combat resistant staphylococci," he said. "At this time there are no products on the market that target this same efflux-inhibitor mechanism. We want to improve the active substance using synthetic chemistry in the laboratory. That will also ensure sustainable production of a potential drug while protecting rainforest plants."

Dr Holler contends that further research will be necessary if we are to regain the advantage in the fight against yellow staphylococci.

"For all intents and purposes, the drug industry is not pursuing research into new antibiotics," he explained. "It is simply too expensive relative to possible earnings, and there is more money in drugs to treat chronic diseases such as diabetes. Therefore, the bacteria are winning the race - resistance increases and treatment options are scarce. Research will have to find new paths and natural substances are one of them."


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