Treatment of isoniazid-resistant tuberculosis in southeastern Texas

Background Isoniazid-resistant tuberculosis (INHr-TB) can be treated successfully with several treatment regimens. However, the optimal regimen and duration are unclear. Studyobjective To analyze the efficacy of treatment regimens used for INHr-TB in the southeastern Texas region. Design Retrospective cohort study. Setting Health-care facilities reporting tuberculosis (TB) patients in the Houston and Tyler areas. Subjects All patients reported to have INHr-TB from 1991 to 1998. Exclusion criteria included poor compliance, additional first-line drug-resistance (except aminoglycosides), and death before completion of 1 month of treatment. Measurements and results Main treatment outcomes were treatment failure, relapse, and TB-related death. Fifty-three of 83 patients were included in the study; aminoglycoside resistance coexisted in 37.5% of isolates. Seven types of treatment regimens were identified. Eighteen patients (34%) received rifampin, pyrazinamide, and ethambutol thrice weekly for 9 months. Four patients (7.5%) had a total effective treatment duration of Conclusions Several treatment regimens were prescribed for INHr-TB in southeastern Texas. INHr-TB treatment durations were > 7 months, and treatment regimen efficacy was adequate. Twice-weekly treatment was associated with relapse, whereas thrice-weekly and daily treatments performed similarly. A prospective study with different treatment durations is needed to determine the optimal treatment regimen for patients with INHr-TB.