RELATIONSHIP OF ISONIAZID RESISTANCE TO HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION IN PATIENTS WITH TUBERCULOSIS

To investigate the relationship between isoniazid resistance and HIV i nfection in patients with tuberculosis, we evaluated data in the Los A ngeles County tuberculosis registry on 1,506 patients for whom drug su sceptibility results were available. Among 235 HIV-infected patients, isoniazid resistance was less common than in 1,271 patients who were H IV-seronegative or who had not been tested for HIV, with an unadjusted odds ratio of 0.3. After adjustment for other factors that affect dru g resistance (ethnicity, country of birth, prior diagnosis of tubercul osis, and cavitation), the frequency of isoniazid resistance remained lower than that in patients without HIV infection, with an odds ratio of 0.4 (95% confidence interval, 0.2 to 0.8; p = 0.02). We conclude th at in Los Angeles, a setting where there is no ongoing outbreak of dru g-resistant tuberculosis, isoniazid-resistant tuberculosis is not more common in HIV-infected patients.