| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2002: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
Recently, efflux pumps that confer multi-drug resistance have come up. We have already reported that the mutation on the 16S rRNA gene indeed contributed to kanamycin resistance in Mycobacterium tuberculosis by use of the conjugation system. Approximately 70% of kanamaycin resistant clinical isolates of M. tuberculosis possessed the mutations on the 16S rRNA gene. 92% of resistant strains, which had no mutation on the 16S rRNA genes, possessed insertional mutation at tap gene encoding putative efflux pump. We studied the role of efflux pumps on drug resistance in mycobacteria. 1)The mutated tap gene offered inhibition of the growth and caused a bit filament formation of host E. coil cell. 2)The difference was not observed in minimum inhibitory concentrations to aminoglycoside, tetracycline, and quinolones in E. coil strains carrying the mutated and wild type tap genes. 3)Recently, P55(Rv1410c) was reported to be a multidrug efflux pump in M. tuberculosis. The mutation of Rv1410c was not related to kanamycin resistance. 4)The mutations of 23S and/or 5S rRNA genes were not related to kanamycin resistance. 5)To avoid the damage of bacterial cells, we used low copy number vector pBR322. The wild and mutated tap genes of M. tuberculosis were cloned into E. coli KAM32, which lacks strong own efflux pumps. We determined MICs to antibiotic including kanamycin, streptomycin, gentamycin, chloramphenicol, and tetracycline. The difference was not observed MICs, and E. coli strains carrying the mutated and wild type tap genes indicated higher resistance in opposite direction of tet promoter. It is in progress to make M. smegmatis system using E. coli-mycobacterial shuttle vector to examine the effect onto mycobacteria.
Glutaraldehyde-tolerant M. chelonae isolates from bronchoscope washing machines were resistant to some antibiotics including rifampisin, its mechanism might be other than efflux pumps.
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