Tuesday, February 21, 2012 

Aggressive infections in hospitals are an increasing health problem worldwide and the development of bacterial resistance is alarming. Now, a young Danish scientist has found a natural substance, present in a Chilean rainforest plant, which effectively supports traditional antibiotic treatment. In a research project, Dr Jes Gitz Holler, University of Copenhagen, discovered a compound that targets a particular resistance mechanism in yellow staphylococci. The development of resistance in these specific bacteria is extremely rapid and strains that do not respond to treatment have already been found in the USA and Greece.

Dr Holler explains: "I have discovered a natural substance in a Chilean avocado plant that is active when combined with traditional antibiotics. Resistant bacteria have an efflux pump in their bacterial membrane that efficiently pumps out antibiotics as soon as they have gained access. This natural substance inhibits the pumping action, breaking down the bacteria’s defence mechanisms and allowing the antibiotic treatment to work." Specimens of the plant, which is part of the Persea family, were gathered in Chile, where the Mapuche people use the leaves of the avocado plant to heal wounds. The results have been published in the Journal of Antimicrobial Chemotherapy.
The lowest possible concentration of an antibiotic that inhibits bacterial growth is referred to as the MIC value — and it can be reduced by at least eight times with the use of this new substance. Holler continues: "The natural compound has great potential and can perhaps in the long-term be developed into an effective drug to combat resistant staphylococci. There are no products currently on the market that target this same efflux-inhibitor mechanism. We want to improve the active substance using synthetic chemistry in the laboratory, which will also ensure sustainable production of a potential drug while protecting rainforest plants." It is believed that such a commercial product would benefit the Mapuche people; at present there is a written agreement between their representative, Dr Alfonso Guzmán, who helped to procure the plant material, and the Faculty of Health and Medical Sciences.
Yellow staphylococcus (Staphylococcus aureus) is the most common cause of post-operative wound infections and can be the cause of many diseases, from abscesses and food poisoning to life-threatening infections such as infective endocarditis and sepsis. The bacteria have been a major problem in hospitals worldwide since the 1940s and, until now, the drug industry has managed to develop new antibiotics to keep step with the increasingly aggressive behaviour of the bacteria. Unfortunately, this ability appears to be waning.
"To all intents and purposes, the drug industry is not pursuing research into new antibiotics; it is simply too expensive relative to possible earnings and drugs to treat chronic diseases, such as diabetes, are more profitable. Therefore, the bacteria are winning the race: resistance is increasing and treatment options are scarce. Research will have to identify new paths and natural substances offer huge potential."

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