[The studies on the molecular mechanism of rifampin-resistant Mycobacterium tuberculosis].
OBJECTIVE
To evaluate the molecular mechanism of rifampin (RFP)-resistance of M. tuberculosis, and to provide evidence of molecular genetics for basic and clinical research of tuberculosis.


METHODS
rpoB gene mutation of M. tuberculosis was detected with PCR-SSCP from 262 clinical isolates, including 74 drug sensitive strains, and 188 RFP-resistant only or multiple drug-resistant strains of M. tuberculosis, collecting from Henan, Hebei and Anhui province, Beijing and Shanghai cities. Plasmids were extracted from 76 clinical isolates of M. tuberculosis with alkaline bacteriolytic methods.


RESULTS
Mean mutation rate of rpoB gene was 92% in the RFP-resistant clinical isolates of M. tuberculosis. Respectively, the mutation rate was 90.0% in Henan province, 94% in Hebei province, 91% in Anhui province, 91% in Beijing city and 92% in Shanghai city. There was no significant difference between results from the provinces and the cities (chi 2 = 0.42, P > 0.05). However, mutation of rpoB gene was not detected in 74 sensitive clinical isolates of M. tuberculosis. Moreover, in 76 clinical isolates of M. tuberculosis the plasmids were not found, including 29 sensitive strains, 33 RFP-resistant only or multiple drug-resistant strains and 14 RFP, isoniazid, streptomycin and ethambutol-resistant clinical isolates.


CONCLUSIONS
This study confirmed the strong correlation between the RFP-resistance and the mutation of the rpoB gene, which might be a major molecular mechanism of RFP-resistance in M. tuberculosis. No evidence shows that M. tuberculosis has the plasmid, which mediates RFP resistance to M. tuberculosis.
Zhuang
Y
Y
309th Hospital, PLA, Beijing 100091, China.
He
X
X
Zhang
X
X
D000904:Antibiotics, Antitubercular / Q000494:pharmacology; D004269:DNA, Bacterial / Q000032:analysis; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics*; D012293:Rifampin / Q000494:pharmacology
D000904:Antibiotics, Antitubercular; D004269:DNA, Bacterial; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit; D012293:Rifampin