ST. PETERSBURG, June 1 (Xinhua) — A substance extracted from meat fly maggots can increase the effectiveness of existing antibiotics, said Russian biologists.According to their research published in the journal Infection and Drug Resistance, the extract can intensify the effect of antibiotics and destroy biofilms – specific groups of microorganisms that complicate wound healing and often cause chronic ulcers, the RIA Novosti news agency reported Friday.Russian scientists are working on the creation of a technology that allow mass production of this extract, the news agency said.