Pattern of Drug Resistance in Pulmonary TB Patients


1 Department of Infectious Disease

2 Department of Pulmonary Medicine, NRITLD, Shaheed Beheshti University of Medical Sciences and Health Services, TEHRAN-IRAN


Background: Tuberculosis is a common infectious disease these days; it has the highest mortality rate among all infectious causes only after HIV/AIDS. The emergence of tuberculous bacillus species resistant to multiple drugs has become a serious global threat to the human health. Drug resistance is either acquired with the initial infection (from a host harboring resistant tubercle bacilli) or develops during treatment with antituberculous chemotherapeutic agents because of poor patients compliance or inadequate/ inappropriate treatment regimens. This study has been done to evaluate drug resistance and to determine the type of resistance in drug resistant tuberculosis patients. Materials and Methods: The files of patients hospitalized during the past 2.5 years in Massih-Daneshvari clinical mycobacteriology ward due to suspected drug resistant tuberculosis were evaluated. Those who had a sputum antibiogram indicating resistance at least to one anti-TB drug were included in the study. Data, including demographic data, radiologic findings, sputum smear, sputum culture, and antibiogram were recorded in a specified questionnaire. Analysis was done for central indices using the SPSS software. Results: Forty-three cases met the inclusion criteria. Twenty-seven (63%) were male and 16(37%) were female with the age range of 16-80 years (mean ±SD, 36.9 ±16.76). Twenty-five cases (58%) were Afghan and 13(30%) were Iranian (Other nationalities had not been recorded). Antibiograms of 38 patients (88%) showed resistance at least to isoniazid and rifampicin; these patients were considered as multidrug resistant (MDR) cases. In 24 cases (56%), the Mycobacterium tuberculosis was resistant to all four-drug isoniazid (INH), rifampicin (RIF), streptomycin (STM), and ethambutol (EMB). Thirty-six patients (85%) had resistance at least to STM, and 26 patients (60%) were resistant at least to EMB. Bacillus drug susceptibility to pirazinamide (PZA) was not specified. Conclusion: Most drug-resistant cases of TB were seen among Afghan emigrants. Ninety-five percent of cases had a history of treatment at least once, and the resistance was secondary (acquired). Despite discontinuation of streptomycin usage as an anti-TB drug in Iran in the recent years, the most common type of resistance was related to this drug, occurring in 85% of cases. Confirming different studies in other countries, the lowest resistance to the first line anti-TB drugs was for EMB, detected in 56% of cases. (Tanaffos 2003; 2(7): 47-51)