Infectious bacteria are becoming more than some clinicians can handle — they are increasingly resistant to antibiotics, and there are few new treatments being tested to combat them, says Not Exactly Rocket Science's Ed Yong. And as recent studies have shown, horizontal gene transfer is even more prevalent than previously thought, which means the bacteria can evolve more rapidly to resist drugs. Researchers at the University of Jyvaskyla in Finland, however, see the gene transfer as a way of defeating the bacteria, Yong says. In a new study in Biology Letters, the university team led by Matti Jalasvuori found that bacteriophages can drastically cut down on the level of drug resistance in colonies of bacteria by "selectively assassinating" plasmid carriers, Yong says. The team added a phage called PRD1 to E. coli and salmonella colonies that had previously been resistant to antibiotics. Within 10 days of the phage going to work, the colonies' populations had dropped to just 5 percent. "The bacteria adapted to the phage assault by jettisoning their plasmids, and with them, their antibiotic-resistance genes. These survivors were now resistant to phages, but the vast majority of them could once again be killed by antibiotics," Yong adds. A small proportion of the bacteria did resist, but the researchers found that they had lost their ability to transfer genes.
Jun 02, 2011