As a result of low drug resistance in pleural tuberculosis (TB), treatment regimens of pleural TB may include fewer drugs and maintain appropriate levels of efficaciousness, according to a study published in the European Journal of Clinical Microbiology & Infectious Diseases.

The effective treatment of TB includes an extended duration of treatment of a combination of at least 3 antibiotics to ensure coverage in case of a resistant strain of bacteria. Occasionally, because of spontaneous mutations, Mycobacterium tuberculosis may show chromosomal resistance against antimicrobial medications, and therefore requires at least 3 drugs in such cases. However, pleural TB has shown a low probability of developing mutations that result in drug resistance, meaning that regimens with fewer drugs could be used because primary resistance is unlikely. Although pleural TB research is lacking, it has been shown that a 6-month regimen of isoniazid and rifampin (6HR) was effective in treating pleural TB; however, regimens with 3 or 4 drugs were not compared for efficacy. Therefore, this study aimed to compare the long-term efficacy of 6-month treatment isoniazid and rifampin with a 6-month treatment regimen of isoniazid, rifampin, and pyrazinamide (6HR2Z) for pleural TB.

In total, 200 patients with pleural TB (male, n=112; female, n=88) who did not have HIV were included. Among the included patients, 99 were treated with an isoniazid and rifampin regimen and 101 were treated with an isoniazid, rifampin, and pyrazinamide regimen.

Results showed that isoniazid and rifampin treatment was as effective as the 3-drug regimen for treatment of pleural TB and had fewer adverse effects. All patients completed the treatment, and compared with participants in the 3-drug group, those in the isoniazid and rifampin group had fewer adverse effects (33% vs 15.3%; P =.005), some of which were rash, pruritus, acne, and digestive intolerance. Compared with the 3-drug regimen, participants who received isoniazid and rifampin had a lower frequency of severe hepatic toxicity (10.9% vs 5%). During the study, 4 patients in the isoniazid, rifampin, and pyrazinamide group died for reasons unrelated to their TB infection. All other patients were cured during a monitoring period of 8.4 years. However, 6 patients in the isoniazid and rifampin group and 10 patients in the 3-drug group developed residual pachypleuritis.

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Overall, the study authors concluded that, “Although the drug resistance seems to be an increasing problem, our results indicate that in many patients with pleural-TB, in areas where resistance to first-line drugs is low, it is not necessary to treat them with the same recommended treatment guidelines for pulmonary TB.”

Reference

Garcia-Rodriguez JF, Valcarce-Pardeiro N, Alvarez-Diaz H, Marino-Callejo A. Long-term efficacy of 6-month therapy with isoniazid and rifampin compared with isoniazid, rifampin, and pyrazinamide treatment for pleural tuberculosis [published online August 3, 2019]. Eur J Clin Microbiol Infect Dis. doi:10.1007/s10096-019-03651-7

This article originally appeared on Infectious Disease Advisor