Transferring toxic genes to other microbes, bacteria gain in virulence

January 7th, 2009 - 4:22 pm ICT by IANS  

New York, Jan 7 (IANS) Scientists have identified a new way whereby bacteria transmit toxic genes to other unrelated bacterial species and gain greater virulence.They also suspect that such exchanges may be more common than previously imagined.

New York University (NYU) School of Medicine scientists discovered that Staphylococcus aureus, a notorious bacterium that causes toxic shock syndrome and is the scourge of hospitals worldwide, 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, said a NYU release.

The startling finding by John Chen and Richard Novick, 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.

When Chen, a postdoctoral fellow in Novick’s lab, suggested doing some transfer experiments with bacteriophages, Novick said “go ahead, but it won’t work.” To his surprise, the bacterial viruses did the completely unexpected.

“We have found that a bacteriophage can transfer genetic elements, or DNA, between unrelated bacterial species in a way that was really not expected,” Novick said.

These findings were published in the January issue of Science.

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