Characterization of a 411-bp fragment of the rpoB gene in clinical isolates of Mycobacterium tuberculosis in a university hospital in northern Taiwan.
OBJECTIVE
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.
Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
Yuang-Shuang
YS
Liaw
Jyy-Jih
JJ
Tsai-Wu
Po-Ren
PR
Hsueh
Shu-Kuang
SK
Wang
Pan-Chyr
PC
Yang
Kwen-Tay
KT
Luh
D000328:Adult; D000368:Aged; D001426:Bacterial Proteins / Q000235:genetics*; D012321:DNA-Directed RNA Polymerases; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics*; D012293:Rifampin / Q000494:pharmacology
D001426:Bacterial Proteins; C505805:rpoB protein, Mycobacterium tuberculosis; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin