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Rifampin-resistant Mycobacterium kansasii
R J Wallace1, D Dunbar, B A Brown
1Department of Microbiology, University of Texas Health Center, Tyler 75710.
Summary
Rifampin-resistant Mycobacterium kansasii infections are increasing, partly due to HIV. However, effective chemotherapy alone offers an excellent prognosis for cure, with most patients achieving negative cultures.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Medicine
Background:
- Identified 36 rifampin-resistant Mycobacterium kansasii isolates, with 17 found in Texas (1989-1992).
- Previous rifampin treatment was common in patients with resistant M. kansasii infections.
- A significant percentage of resistant isolates since 1989 were from human immunodeficiency virus (HIV)-positive patients.
Purpose of the Study:
- To evaluate the effectiveness of chemotherapy in treating infections caused by rifampin-resistant Mycobacterium kansasii.
- To assess factors influencing treatment outcomes, including prior drug exposure and HIV status.
Main Methods:
- Retrospective analysis of M. kansasii isolates and patient data.
- In vitro susceptibility testing guided four-drug chemotherapy regimens.
- Treatment outcomes, including culture conversion and relapse rates, were monitored.
Main Results:
- Ninety percent of treatments resulted in negative sputum cultures, with a mean conversion time of 11 weeks.
- Relapses were more frequent in patients with shorter culture-negative periods (< or = 6 months).
- Chemotherapy alone, without surgery, demonstrated high efficacy.
Conclusions:
- Chemotherapy alone provides an excellent prognosis for curing rifampin-resistant M. kansasii infections.
- The increasing incidence of these resistant infections is partly linked to the HIV epidemic.
- Adherence to longer treatment durations appears crucial for preventing bacteriologic relapse.