Germ warfare

 作者:裘掘辘     |      日期:2019-03-07 06:01:02
By Emma Young, San Francisco From the annual meeting of the American Association for the Advancement of Science in San Francisco Spiking cattle feed with ‘friendly’ bacteria eliminates the dangerous strain E coli 0157 from their intestinal tracts, says a US team. The approach should be a cheap, highly effective method of reducing human exposure to the deadly pathogen, they say. E coli 0157:H7 poisons tens of thousands of people every year. It is transmitted to humans mainly through infected beef or through exposure to cattle manure. Vaccines for use on cattle are available but Michael Doyle of the University of Georgia thinks bacteria could be a better weapon. His team identified about 1,200 strains of bacteria from cattle not infected with E. coli 0157:H7. Next, they isolated strains of E coli that produce antimicrobial agents that kill E coli 0157. When these bacteria were sprayed onto feed, E coli 0157 was eliminated from 80 to 90 per cent of the cattle. “In most animals, friendly E coli will out-compete 0157 in two weeks. It’s like germ warfare in the animal,” Doyle says. The friendly E coli are an ideal weapon against the deadly strain because they colonise exactly the same parts of a cow, says Doyle. Vaccines do not prevent infected animals from shedding E coli 0157 in their faeces, he says. “But our new probiotic treatment shows great promise in this area.” The treatment is also cheap. Doyle estimates that it would cost less than 50 cents per animal. He hopes that similar approaches to combating other bacteria that target humans, such as campylobacter in chickens,