Background and purpose: This study analyzed rpoB gene mutation and its correlation with demographic and clinical data, and the drug resistance profile in 41 consecutive patients with rifampin (RIF)-resistant Mycobacterium tuberculosis isolated at National Taiwan University Hospital from 2000 to 2002.
Methods: The 411-bp fragment of the rpoB gene from 94 M. tuberculosis isolates (including 41 RIF-resistant and 53 RIF-susceptible isolates) was amplified and sequenced.
Results: Of the 41 RIF-resistant isolates, 87.8% (36/41) showed mutations in rpoB. The following mutations were identified: Ser531 (68.3%), His526 (9.8%), Ser522 (4.9%) and Gln513 (4.9%). No silent substitutions were observed. No mutation within the entire 411-bp fragment was found in 12.2% (5/41) of the RIF-resistant isolates and 100% (53/53) of the RIF-susceptible isolates. Patients whose RIF-resistant isolates did not have rpoB mutation had higher frequencies of the following characteristics: elderly, no previous history of tuberculosis, human immunodeficiency virus-negative, no extrapulmonary tuberculosis involvement and favorable prognosis. Drug resistance patterns in RIF-resistant M. tuberculosis strains were significantly correlated with isoniazid resistance, i.e., multidrug-resistant strains (90.2%).
Conclusions: RIF-resistant M. tuberculosis isolates with rpoB mutation were clustered in the 69-bp core region in this study. Rapid detection of RIF resistance could be achieved by testing for rpoB mutation in Taiwan.