Gonorrhea Evolved by Looting Human DNA, Scientist Says

We have met the enemy -- and he is us?

The first direct transfer of human DNA to bacteria was recently discovered by researchers in an unlikely source: gonorrhea.

Northwestern Medicine researchers discovered that Neisseria gonorrhoeae, the bacterium that causes gonorrhea, had evidence of a human DNA fragment. And further research shows this transfer as an evolutionary event.

The finding provides more insight into the sexually transmitted disease -- one of few exclusive to humans -- showing its ability to evolve and thrive in its hosts.

"This has evolutionary significance, because it shows you can take broad evolutionary steps when you're able to acquire these pieces of DNA," said Hank Seifert, professor of microbiology and immunology at Northwestern University's Feinberg School of Medicine, in a statement.

"The bacterium is getting a genetic sequence from the very host it's infecting. That could have far reaching implications as far as how bacteria can adapt to the host."

The discovery has researchers wondering if the extra DNA will lead to new strains of the disease, but as Seifert said in a statement on the school's website, “whether this particular event has provided an advantage for the gonorrhea bacterium, we don't know yet.”

Researchers discovered the transfer while studying the genomic sequences of gonorrhea at the Broad Institute in Cambridge, Mass. They found that three of the 14 isolates had DNA where the sequence of bases (As, Ts, Cs and Gs) was identical to DNA found in humans.

The bacterium that causes meningitis, Neisseria meningitidis, was also tested and found to be genetically similar to gonorrhea, but with no sign of human fragment, showing gonorrhea’s particular gene transfer to be an evolutionary event.

Fifty million people acquire gonorrhea every year worldwide. The disease can be treated through antibiotics, but can lead to pelvic inflammatory disease in women, and in rare cases can enter the bloodstream to cause arthritis and heart infection.