[Study on the characteristics of mutation on Mycobacterium tuberculosis rifampicin-resistance gene].
OBJECTIVE
To elucidate the characters of rpoB mutation in rifampin-resistant clinical isolates of Mycobacterium tuberculosis.


METHODS
286 bp DNA fragment of rpoB gene including 81 bp code region (rifampin resistance deteremination region, RRDR) was analyzed by PCR-single-strand conformation polymorphism(SSCP). The 286 bp DNA fragment of each strain which had been proved to have mutation by PCR-SSCP was then sequenced. 110 strains of M. tuberculosis, including 73 rifampin-resistant strains, 11 rifampin-susceptible drug-resistant strains and 26 drug-susceptible strains were studied.


RESULTS
47 rifampin-resistant strains were detected to have mutations by PCR-SSCP method. 76.6% rifampin-resistant strains showed that rpoB gene was carrying single point mutation analyzed by direct sequencing technique, which mainly located at 531-Ser (61.1%) and 526-His (25.0%). The combined mutation rate was 23.4%. In addition, 2 rifampin-susceptible drug-resistant strains and 1 drug-susceptible strain were mutated, detected by PCR-SSCP method. Sequencing results showed that the mutations located at 511-Leu, 526-His and 535-Pro.


CONCLUSIONS
Mutations in the 81 bp RRDR of rpoB were the main reasons of M. tuberculosis resistant to rifampin. 531-Ser and 526-His were the most common positions of mutations.
Liu
Jing-hua
JH
State Key Laboratory for Infectious Diseases Prevention and Control , National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China.
Zhang
Li-shui
LS
Liu
Zhi-guang
ZG
Huang
Ming-xiang
MX
Zhao
Xiu-qin
XQ
Wang
Lin
L
Wan
Kang-lin
KL
D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D004252:DNA Mutational Analysis; D012321:DNA-Directed RNA Polymerases; D024881:Drug Resistance, Bacterial; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics*; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D012293:Rifampin / Q000494:pharmacology*
D000904:Antibiotics, Antitubercular; D001426:Bacterial Proteins; C505805:rpoB protein, Mycobacterium tuberculosis; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin