Durable remission after successful treatment of multidrug-resistant tuberculosis (MDRTB) among HIV-negative patients

We have previously described a 96% response rate to treatment among HIV-negative patients with MDRTB (resistance to at least isoniazid and rifampin). However, relapses may occur after treatment and initial median follow-up was only 22 months. Longer-term follow-up data for this cohort are now presented. All cases of MDRTB among confirmed HIV-negative persons at 7 New York City teaching hospitals were identified. Therapeutic response was evaluated by microbiologic and clinical criteria. Duration of follow-up was defined as the interval between the date appropriate therapy was initiated and the date of the last contact. Between 3/91 and 9/94, 25 patients were identified. Median age was 37 years and 14 (56%) were male. Fifteen (60%) patients were Black, 4 (16%) Hispanic, 4 Asian and 2 White. Seventeen (68%) had previously established risk factors for MDRTB, of whom 9 had known exposures to MDRTB including 8 health care workers. Twelve patients had isolates resistant to ≥ 4 first-line TB agents. Of the 25 patients, 22 (88%) responded to ≥ 3 drugs with in vitro activity against the isolate and remain free of disease (median of 44.5 months). One patient (4%) relapsed (after 17 months of treatment) and he responded to retreatment with 3 drugs with in vitro activity against the isolate. As previously reported, one patient died of overwhelming tuberculosis without receiving appropriate therapy and one resolved without treatment and remains in remission 71 months after diagnosis. With almost 4 years of follow-up, the relapse rate among HIV-negative persons with MDRTB is low. Patients can be expected to maintain durable remissions after responding successfully to appropriate treatment.