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CDC launches action plan to combat XDR-TB
Educating HCWs important to prevent spread
Although tuberculosis has reached an all-time low in the United States, the persistence of TB globally including extensively drug-resistant (XDR)-TB means that U.S. hospitals must remain vigilant to prevent spread of the disease, public health experts say.
An action plan to combat XDR-TB released by the Centers for Disease Control and Prevention promises more guidance on infection control, better lab resources and a focus on education of health care personnel. Health care workers are at greatest risk from the undiagnosed case,1 says Philip LoBue, MD, associate director for science in the CDC's Division of Tuberculosis Elimination.
Even hospitals in communities with a low prevalence of TB must be alert to the possibility, especially among foreign-born individuals or those who have visited countries in which TB is still endemic, he says. "It's not unusual to see outbreaks of transmission in places that don't usually have a lot of TB because they're not looking for it and they don't expect it," LoBue says.
The specter of extensively drug-resistant TB, which doesn't respond to first- or second-line antibiotic treatments, has focused new attention on the worldwide threat of TB. In 2006, there were 9.2 million cases of TB globally and 1.7 million deaths, according to the World Health Organization. India, China, Indonesia, South Africa, and Nigeria have the highest number of TB cases overall, and India, China, and Russia have the most drug-resistant strains.
"Overall, in the United States, the [TB] risk is low. Globally, it's a different story," says LoBue. "There are estimated to be about 500,000 MDR [multidrug-resistant] TB cases in the world. The estimates of how many of those are XDR are fairly rough, but probably 7% are XDR, or 35,000 cases globally."
There's no reason for U.S. health care workers to be fearful of XDR-TB, says LoBue. Administrative and engineering controls, such as the isolation of patients with suspected TB need to be isolated in a negative pressure room, and respiratory protection reduce risk of transmission, he says.
"There's no reason to think [XDR] is more transmissible [than other forms of TB]," he says. "Back in the mid-1980s through early 1990s, we had about four times the amount of MDR-TB in the United States than we do now, and there was definitely transmission occurring in health care settings. Implementing those [guidelines] was effective in stopping transmission."
In promising news, researchers at the National Institute of Allergy and Infectious Diseases found that two existing antibiotics meropenem and clavulanate may be effective against XDR-TB. The combination stopped the growth of 13 strains of XDR-TB in the laboratory.2
"Right now, there are probably four or five [new drug regimens] in the pipeline in various stages of clinical trials," says LoBue. "A number of them are promising, but it's going to take another decade or so before we really know how effective they are."
An ongoing major clinical trial also is investigating a shorter regimen for treating latent TB infection, which may improve compliance, says LoBue. Results of that trial are expected in about two years.
XDR-TB results from poorly treated TB
At the New Jersey Medical School Global Tuberculosis Institute in Newark, executive director Lee Reichman, MD, MPH, is pleased to see heightened attention to combating TB. But he notes that the worldwide burden of TB drug-resistant or not is great enough to warrant an "action plan."
"Since TB is a preventable, curable disease and it kills more people than any single infection worldwide, they should have done something before waiting for the XDR outbreak," he says.
Every case of XDR-TB can be traced back to a case of susceptible TB that was not treated fully, Reichman notes. "If you treat regular TB properly, you don't get MDR. If you treat MDR properly, you don't get XDR," he says.
While health care workers need to be alert for TB as a possible diagnosis, developing countries need better lab capabilities and improved surveillance, Reichman says.
"Anybody can get TB," he says. "To control TB anywhere, we need to control it everywhere. We need to control TB where the hotbeds are."
LoBue offers the following advice to minimize the risk of TB transmission in hospitals:
Be aware of the patients who are at higher risk for tuberculosis and have symptoms consistent with the disease: weakness, weight loss, fever, night sweats, persistent cough, chest pain, and the coughing up of blood. In the United States, about half of cases among foreign-born individuals were from Mexico, the Philippines, India, and Vietnam.
Be sure that health care workers comply with the infection control measures that their institution has in place because experience tells us they are effective.
Health care workers should feel secure when they're caring for patients that if they're following the recommended infection control practices they have no significant risk.
Promote awareness and combat complacency. "Complacency leads to problems and breakdowns in people not adhering to control measures that we know work," he says.
1. Centers for Disease Control and Prevention. Plan to combat extensively drug-resistant tuberculosis: Recommendations of the Federal Tuberculosis Task Force. MMWR 2009; 58(RR03): 1-43.
2. Hugonnet JE, Tremblay LW, Boshoff HI, et al. Meropenem-clavulanate is effective against extensively drug-resistant Mycobacterium tuberculosis. Science 2009; 323:1,215-1,218.