Tuberculosis treatment requires medication and monitoring

Tuberculosis (TB) continues to be a problem in the United States, particularly among at-risk populations. The groups at highest risk for TB include people living with someone who has active disease, and those with a lowered immune response, such as HIV patients.

“Every medical center in our region has tuberculosis on its risk assessment list, that is, its list of potential issues to monitor on a continuing basis,” says Stephen Parodi, MD, chief of infectious disease for Kaiser Permanente, Northern California. “We make it a priority to ensure that patients at risk for infection with TB are screened for latent infections.”

The region includes 20 medical centers serving 3.1 million members. Dr. Parodi says the plan encourages screening for those who have been incarcerated or have a history of IV drug use and has educated primary care physicians and pediatricians to screen for TB.

“We saw a significant surge in TB cases when the HIV epidemic first hit; since then we’ve seen a leveling off,” he says. “In terms of epidemiology, it’s interesting to note that many cases we’re now seeing are in foreign-born individuals. We live in a global world, and we need to be aware that constant vigilance and aggressive, early recognition of latent and active disease will prevent further spread.”

Most people infected with tuberculosis don’t have any symptoms. When a patient is positive for latent TB, the clinician looks at the risk factors and determines (based on criteria from the Centers for Disease Control) whether the person is a candidate for preventive medicine.

“Preventive medicine is a lot easier than treating the active form of the disease,” Dr. Parodi says. “With latent disease we can treat with one drug, as opposed to active disease, where we typically have to use a minimum of four drugs initially.”

Patients who develop active TB experience symptoms such as weight loss, fever, night sweats, cough, chest pain and bloody sputum.

“Until susceptibility results are available, empiric initial treatment for active TB should include four drugs: isoniazid, rifampin, pyrazinamide and ethambutol,” says Mark Abramowicz, MD, editor-in-chief of The Medical Letter on Drugs and Therapeutics, a non-profit newsletter that critically appraises drugs. “When susceptibility to isoniazid, rifampin and pyrazinamide has been documented, ethambutol can be omitted.”

DIRECT PATIENT OBSERVATION NEEDED

One of the greatest problems in TB treatment today is the emergence of drug-resistant strains of the bacteria.

“Poor adherence to TB therapy is the most common cause of treatment failure, and can lead to drug resistance,” says Dr. Abramowicz. “Medical Letter consultants recommend that most patients, including those with disease due to drug-susceptible strains, take drugs for active TB under direct observation.”

At Kaiser, patients with active TB are monitored closely, typically with a monthly office visit. Kaiser physicians sign the orders for directly observed therapy, which is provided by the county public health department.

“We provide medications, lab testing to monitor potential side effects, symptom assessments, and imaging, x-rays or CT scans as needed,” Dr. Parodi says. “Protocols differ from jurisdiction to jurisdiction in terms of exactly who gets directly observed therapy, but in our experience, most counties are aggressive. If there is an identified case of active, potentially contagious TB, that person is receiving directly observed therapy.”

Extensively drug-resistant TB is a form of the disease caused by strains that are resistant to all the most effective anti-TB drugs. The World Health Organization reports that 41 countries have cases of extensively drug-resistant TB, including the United States.

“Confirmed multidrug-resistant tuberculosis and extensively drug-resistant tuberculosis should be treated with directly observed therapy in collaboration with a clinician familiar with management of these conditions,” says Dr. Abramowicz. “Regimens for these conditions must include at least four drugs to which the organism is susceptible; the duration of therapy usually should be 18 to 24 months.”

In recent years, researchers have made considerable progress toward developing new medications that could treat tuberculosis more effectively. Eleven new medications from seven different drug classes are currently in clinical trials for tuberculosis.

“The medications that are farthest along are antibiotics called fluoroquinolones, which have the potential to shorten the duration of therapy,” says Eric Nuermberger, MD, associate professor of medicine and international health at Johns Hopkins School of Medicine, who is on the faculty of Hopkins’ Center for Tuberculosis Research. “Current medications require six to nine months; we hope fluoroquinolones will reduce that to four months. Four phase II studies of fluoroquinolones are currently underway, and we should have an answer in about two years.”

Fluoroquinolone drugs are already on the market in the United States for acute conditions such as community-acquired respiratory tract infections and urinary tract infections.

Of the medications that are being developed solely for tuberculosis, the one that’s furthest along is TMC207, developed by Tibotec.

According to a recent study in The New England Journal of Medicine, when researchers added TMC207 to a standard regimen for multidrug-resistant tuberculosis, a significantly higher proportion of patients had negative sputum cultures at two months.

Elaine Zablocki has been reporting on healthcare for more than 20 years. She is based in Oregon.

This article is based on information supplied by The Medical Letter (www.medicalletter.org), a non-profit organization that publishes newsletters offering critical appraisals of new drugs and comparative reviews of older drugs. The Medical Letter is independent of the pharmaceutical industry and supported entirely by subscription sales. Institutional site license inquiries can be sent to info@medicalletter.org [info@medicalletter.org]

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