Rifamycin Resistance Seen in AIDS Patients With TB Receiving Intermittent Therapy

Originally published by Reuters Health, March 15, 2002

NEW YORK (Reuters Health) — In a "Notice to Readers," the US Centers for Disease Control and Prevention (CDC) warn that once- or twice-weekly therapy with rifamycin for patients co-infected with HIV and Mycobacterium tuberculosis has resulted in cases of rifamycin resistance.

The CDC's TB Trials Consortium Study 23 was initiated to evaluate twice-weekly rifabutin-based therapy in co-infected patients. The study was suspended when five patients acquired resistance to rifamycin. The patients were characterized by CD4 cell counts <60/ L when TB was diagnosed. Four patients had received the twice-a-week therapy during both the intensive and the continuous phase of treatment.

In the agency's Morbidity and Mortality Weekly Report, the CDC recommends that HIV-TB co-infected patients with CD4 cell counts below 100/ L undergo directly observed therapy with daily doses of rifabutin during the intensive phase of treatment, and no less than three doses a week during the continuation phase.

The agency does not advise any steps be taken in clinically stable patients who have completed TB therapy. However, clinicians should be alert to the development of rifamycin resistance, conducting susceptibility testing and implementing regimens active against rifamycin-resistant TB in cases of suspected TB relapse.

The currently recommended duration of treatment appears to be fine, the CDC writes. The 6-month minimum treatment should be extended to 9 months only if patients exhibit a delayed response to rifamycin.