TREATMENT OF TB

Today, the treatment of tuberculosis consists of drug therapy and methods to prevent the spread of infectious bacilli. Historically, treatment of tuberculosis consisted of long periods, often years, of bed rest and surgical removal of useless lung tissue. In the 1940s and ’50s several antimicrobial drugs were discovered that revolutionized the treatment of patients with tuberculosis. As a result, with early drug treatment, surgery is rarely needed. The most commonly used antituberculosis drugs are isoniazid and rifampicin (rifampin). These drugs are often used in various combinations with other agents, such as ethambutol, pyrazinamide, or rifapentine, in order to avoid the development of drug-resistant bacilli. Patients with strongly suspected or confirmed tuberculosis undergo an initial treatment period that lasts two months and consists of combination therapy with isoniazid, rifampicin, ethambutol, and pyrazinamide. These drugs may be given daily or two times per week. The patient is usually made noninfectious quite quickly, but complete cure requires continuous treatment for another four to nine months. The length of the continuous treatment period depends on the results of chest X-rays and sputum smears taken at the end of the two-month period of initial therapy. Continuous treatment may consist of once daily or twice weekly doses of isoniazid and rifampicin or isoniazid and rifapentine.




If a patient does not continue treatment for the required time or is treated with only one drug, bacilli will become resistant and multiply, making the patient sick again. If subsequent treatment is also incomplete, the surviving bacilli will become resistant to several drugs. Multidrug-resistant tuberculosis (MDR TB) is a form of the disease in which bacilli have become resistant to isoniazid and rifampicin. MDR TB is treatable but is extremely difficult to cure, typically requiring two years of treatment with agents known to have more severe side effects than isoniazid or rifampicin. Extensively drug-resistant tuberculosis (XDR TB) is a rare form of MDR TB. XDR TB is characterized by resistance to not only isoniazid and rifampin but also a group of bactericidal drugs known as fluoroquinolones and at least one aminoglycoside antibiotic, such as kanamycin, amikacin, or capreomycin. Aggressive treatment using five different drugs, which are selected based on the drug sensitivity of the specific strain of bacilli in a patient, has been shown to be effective in reducing mortality in roughly 50 percent of XDR TB patients. In addition, aggressive treatment can help prevent the spread of strains of XDR TB bacilli.