Aug. 27 (Bloomberg) -- The stomach may be a breeding ground for drug resistance, a study finds.

Bacteria that fails to respond to standard treatments have been a growing concern since 2006, when methicillin-resistant Staphylococcus aureus, or MRSA, killed more people in the U.S. than HIV/AIDS, the report noted. The study by Harvard Medical School geneticist George Church found a plethora of genes in DNA from saliva and fecal samples that allowed resistance to antibiotics when added to the E. coli bacteria.

The report, published today in the journal Science, suggests that more research must be done on this newly discovered cluster to determine whether it is somehow adding to the difficulty of treating drug-resistant germs, said Stuart Levy, director for the Center for Adaptation Genetics and Drug Resistance at Tufts University in Boston.

“Now the question is why are they there, and what are they doing?” Levy, referring to the gut-based bacteria, said today in a telephone interview. “Were these there in cavemen, or are they fairly new and coming from somewhere else?” The paper doesn’t say, said Levy, who wasn’t involved in the research.

Initially, researchers were studying the resistance of soil bacteria to antibiotics and wanted to see if the soil was more dangerous than the human mouth, Church said.

“There was a lot more resistance in the uncultured bacteria,” said Church, in an Aug. 26 telephone interview from his Boston office.

New Technique

The scientists used multiple drugs at the same time to see if there was resistance. Usually, researchers examine one drug at a time, Church said. The new method of discovering antibiotic resistance may make it easier to diagnose a doctor’s guess that a germ is drug-resistant.

“We’re getting closer to a time where you can just sequence all kinds of things and immediately know what organisms are involved,” Church said. That would be faster than the current method of guessing and checking.

While antibiotic use may not create resistant bacteria, it does make it easier for drug-resistant bugs to spread by wiping out susceptible germs, said Levy. That’s why it’s important to use antibiotics as they’re prescribed, without stockpiling or stopping treatment early. It would be interesting to see what happens to these gut bacteria when a person is given antibiotics, he said.

To contact the reporter on this story: Elizabeth Lopatto in New York at elopatto@bloomberg.net.

Last Updated: August 27, 2009 14:00 EDT