Sept. 20--The emergence of any drug-resistant bacteria is the kind of news infectious-disease experts loathe hearing.
The discovery that the new bacteria NDM-1 has infected at least three U.S. residents -- all of whom had medical care in India -- has them concerned but not panicked.
Drug-resistant infections can be deadly, and the tools to fight them are limited.
This is just one more reason that doctors and patients need to take seriously the warning that antibiotics should be used only when necessary, said Dr. Madhuri Sopirala, an epidemiologist and infectious-disease specialist at Ohio State University Medical Center.
The overuse of antibiotics contributes significantly to resistance. About one-third of antibiotic prescriptions aren't necessary, according to the federal Centers for Disease Control and Prevention.
This new bacteria is in a class called gram negative, which makes it even more of a concern than more-common superbugs, including methicillin-resistant Staphylococcus aureus, or MRSA, Sopirala said.
"It's very problematic ... these are actually more of a challenge to treat because the drugs that we have available are very limited," she said.
The bug is moving through India, Pakistan and Bangladesh at a good clip and has been found across the United Kingdom. A related bacteria, known as CRKP, is emerging in the United States, prompting the CDC to issue guidelines last year for controlling infections. Both are resistant to carbapenem, one of the last-resort antibiotics for many infections.
Sopirala said infectious-disease doctors in the United States have been asked to take a close look at antibiotic-resistant infections in an effort to identify any additional NDM infections in this country.
"We must continue judicious use of antibiotics to try to curb or curtail this," said Dr. Larry Schlesinger, who directs Ohio State's division of infectious diseases and the Center for Microbial Interface Biology.
As cold and flu season begins, it bears mentioning: Antibiotics do nothing for colds and nothing for the flu, which is caused by a virus. Most sore throats also are caused by viruses, not bacteria. So if you demand antibiotics from your doctor, and he or she complies, you might contribute to the problem by encouraging mutations and making yourself more vulnerable when you truly need antibiotics.
From January 2006 through October 2007, a total of 28,502 drug-resistant infections acquired within hospitals were reported to the CDC's National Healthcare Safety Network.
Bacteria develop resistance to conventional antibiotics through mutations, or changes in the genetic material. They also can become resistant by exchanging genes with other bacteria.
"I see this as just another example of a continuing crisis," Schlesinger said. "The pipeline for new drug discovery against infectious diseases remains small."
Schlesinger and his colleagues are working to screen different compounds to see what might work against infectious diseases and are looking to partner with pharmaceutical companies to bring discoveries to the market.
Although there's not much in the way of market-ready new drugs, there is some promise in Ohio and in labs nationwide.
This past week, a biochemist at Case Western Reserve University in Cleveland shared news of his discovery of compounds that, without killing the bacteria like an antibiotic would, could render MRSA harmless.
The drugs prevent the production of toxins that make people sick, and the concept has potential applications for other antibiotic-resistant bugs, said the researcher, Menachem Shoham, an associate professor at Case Western.
A potential side benefit to such treatments is that they'd be unlikely to contribute to antibiotic resistance, he said. The research is in early stages and far from use in clinical applications, but it offers some hope in the quest to better fight resistant bacteria, Shoham said.
In the meantime, he joins the chorus calling for careful use of antibiotics, pointing to developing countries where the medicines don't require a prescription and to the widespread agricultural use of prophylactic antibiotics as problems that need addressed.
"It only takes a few months before a resistant bug travels all over the world and can become a real dangerous and nasty superbug," Shoham said.
mcrane@dispatch.com
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