New Drug-Resistant 'Superbug' Reaches U.S. Shores
But the nation already has its own version of this antibiotic-resistant bacteria, CDC says
TUESDAY Sept. 14, 2010 (HealthDay News) -- A new antibiotic-resistant germ that apparently has it origins in India has sickened a handful of people in North America, with three of the cases reported in the United States, health officials said Tuesday.
But the bacterium -- designated New Delhi metallo-beta-lactamase NDM-1 -- is a close genetic cousin of another bacterium that's been present in the United States for many years. Both germs produce an enzyme that makes them resistant to a group of antibiotics called carbapenems, which include drugs such as penicillin and ampicillin.
"NDM-1 is a newly recognized mechanism of resistance that allows certain bacteria to become resistant to certain antibiotics," said Dr. Alexander J. Kallen, a medical epidemiologist and outbreak response coordinator with the U.S. Centers for Disease Control and Prevention's Division of Healthcare Quality Promotion.
"Unfortunately, carbapenem resistance is not uncommon even in the United States," Kallen added. "We have our own homegrown version of NDM-1 that has been recognized for quite a few years."
In the United States, carbapenem-resistant bacteria -- designated carbapenem-resistant carbapenemase (KPC) -- are usually transmitted in health-care facilities such as hospitals and nursing homes, and are typically spread from patient to patient from contaminated surfaces and hands, he said.
While none of the patients in the United States died from their infections with the NDM-1 germ from India, people should be very concerned about this new breed of germs that are showing resistance to carbapenem antibiotics, Kallen said.
"What is new in NDM-1 is a new mechanism that produces a strain [of bacterium] that looks the same as KPC," Kallen said.
NDM-1 appears to have started in India and is now found in countries such as Canada, Pakistan and some nations in Europe. Some people have died from their infections, but Kallen couldn't say how many.
In the United States, three cases have been reported. They were in Massachusetts, Illinois and California, Kallen said. None of the U.S. patients died from their infections, he said.
While NDM-1 is new, carbapenem resistance has been increasing, Kallen said.
How dangerous NDM-1 will become isn't known, Kallen said. But some studies have found the death rate from KPC [the North American bacterium] to be as high as 40 percent, he said.
Most of the transmission of the NDM-1 (Indian) and the KPC (North American) bacteria happen as infected people travel around the world, Kallen added. "These people carry with them all their antibiotic-resistant bacteria and that mechanism [travel] has been recognized lots of times, including with NDM-1 and KPC," he said.
Kallen said routine testing can reveal bacteria resistance. "As far as treating the patient or infection control, it doesn't matter what the mechanism is -- they're all bad and they all need to be controlled in the same way," he said.
Hospitals that identify cases of NDM-1 or KPC infection should isolate the patient before treatment. Hospitals should also check to see if other patients have had contact with infected patients.
One of the most common ways that bacteria become resistant to antibiotics is through the overuse of the drugs, Kallen noted.
Infectious diseases expert Dr. Marc Siegel, an associate professor of medicine at New York University in New York City, said that "the number of [NDM-1] cases is small, but what is concerning about this is this is a new bacteria that is emerging because of a genetic change that is causing a garden-variety bacteria to become resistant to most antibiotics."
Antibiotic-resistant bacteria are emerging because of lack of cleanliness and sterility in hospitals, too many antibiotics being prescribed, and drug companies not developing new antibiotics because they aren't profitable, Siegel said.
Dr. Pascal James Imperato, dean and distinguished service professor at the School of Public Health at SUNY Downstate Medical Center in New York City, explained: "Bacteria with this resistance capability are most likely to pose a problem first in hospitals. Some antibiotics are still effective against NDM-1. The first three cases in the U.S. were successfully treated. It is difficult to predict the future role of NDM-1 bacteria since they were only first detected in December, 2009."
For more information on antibiotic resistance, visit the U.S. Centers for Disease Control and Prevention.