Rifabutin Cross-resistance and Associated rpoB Mutations in Rifampicin-resistant Mycobacterium tuberculosis Complex Isolates

OBJECTIVE: mutations associated with rifabutin susceptibility. MATERIAL AND METHODS: gene were investigated by Sanger sequencing. RESULTS: Among the 43 rifampicin-resistant isolates, 39 (91%) were resistant to rifabutin, while four (9%) remained susceptible. All rifampicin-susceptible isolates were also susceptible to rifabutin. A total of 44 non-synonymous single nucleotide polymorphisms were detected in rifampicin-resistant isolates, whereas no mutations were observed in the control group. Seven distinct mutation patterns were identified, including one isolate with a double mutation. The most common mutations were S531L (76%), H526Y (12%), and D516Y (4%). The mutations D516Y, L511P, and L533P, as well as the M515I+D516Y double mutation, were associated with rifabutin susceptibility. CONCLUSION: studies, including minimum inhibitory concentration testing, and additional clinical data on rifabutin-containing regimens are needed.