Determination of risk factors for isoniazid monoresistance and multidrug-resistant tuberculosis in treatment failure patients.

India has a high number of drug-resistant tuberculosis cases. Patient records were screened to determine risk factors possibly associated with monoresistance and multidrug-resistant tuberculosis (MDR-TB) in comparison with patients with susceptible TB. We retrospectively screened and selected 250 patient records from a tertiary care centre, in which detailed clinical histories were provided. Of the 250 patients, 10 had isoniazid monoresistant TB, 184 patients had MDR-TB, and 56 patients had TB susceptible to first-line drugs. Binary regression analysis revealed that previous treatment with a fluoroquinolone and an injectable other than streptomycin (odds ratio (OR) 3.889, 95% confidence interval (CI) 1.828-8.272) was associated with MDR-TB. Previous history of TB (OR 0.697, 95% CI 0.363-1.338) and the presence of cavities on radiographs (OR 0.371, 95% CI 0.160-0.862) did not show any association. None of these reported risk factors were associated with isoniazid monoresistance. In conclusion, a history of previous treatment with a fluoroquinolone and an injectable other than streptomycin was found to be a risk factor for MDR-TB.