NYU scientists discover dangerous new method for bacterial toxi...( NEW YORK Jan. 6 2009 Scientists hav...)

NEW YORK, Jan. 6, 2009 Scientists have discovered a new way for bacteria to transfer toxic genes to unrelated bacterial species, a finding that raises the unsettling possibility that bacterial swapping of toxins and other disease-aiding factors may be more common than previously imagined.

In a laboratory experiment, the scientists from NYU School of Medicine discovered that Staphylococcus aureus, a notorious bacterium that causes toxic shock syndrome and many other types of infections and is the scourge of hospitals nationwide due to its growing antibiotic resistance, could co-opt viral parasites as secret pipelines for transferring toxin genes to vastly different bacterial species.

Microbes have been known to gain antibiotic resistance through the transfer of plasmids, extra-chromosomal pieces of DNA that can be shuttled between unrelated bacteria. Some Staph aureus strains, in particular, have become major public health concerns after gaining antibiotic resistance through plasmids transferred from other species.

The startling new finding, published in the Jan. 2, 2009, issue of Science by John Chen, Ph.D., and Richard Novick, M.D., suggests that Staph aureus also can take advantage of bacteriophages, viruses that infect bacteria, to pass genetic material on to completely unrelated bacteria. In the lab, the researchers showed that Staph could transfer genes for deadly toxic shock to Listeria monocytogenes, which is already known to cause a potentially deadly form of food poisoning. This is the first time that phages have been observed to serve as shuttle vehicles for bacterial toxins between different species.

The experiments were part of a general exploration of bacteriophages. Until now, scientists did not believe that bacterial viruses could transfer genes between unrelated bacterial species. When Dr. Chen, a postdoctoral fellow in Dr. Novick's laboratory, suggested doing some transfer experiments with bacteriophages, Dr. Novick,
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