| Autor: |
Soto, Carlos Y., Mene´ndez, M. Carmen, Pe´rez, Esther, Samper, Sofi´a, Go´mez, Ana B., Garci´a, Mari´a J., Marti´n, Carlos |
| Zdroj: |
Journal of Clinical Microbiology; January 2004, Vol. 42 Issue: 1 p212-219, 8p |
| Abstrakt: |
ABSTRACTDrug resistance in Mycobacterium tuberculosiscomplex strains is solely due to chromosomal mutations that could affect bacterial virulence. Molecular epidemiology studies have shown that resistant strains are less likely to be clustered than susceptible strains. However, a few multidrug-resistant (MDR) M. tuberculosiscomplex strains have been described as causing outbreaks, suggesting that they have restored virulence or increased transmission. One of the biggest MDR tuberculosis outbreaks documented to date was caused by the B strain of M. bovis. Restriction fragment length polymorphism fingerprinting revealed that the B strain contains two copies of IS6110. Here, we mapped and sequenced the regions flanking the two copies of IS6110in the B strain. Ligation-mediated PCR showed that one of these IS6110copies is located within the promoter region of phoP, a transcriptional regulator that is essential for M. tuberculosisvirulence. We used PCR to screen 219 MDR M. tuberculosiscomplex strains (90.4% of all MDR isolates) isolated in Spain between 1998 and 2002 and found that the B strain was the only strain that contained a copy of IS6110in the phoPpromoter. To determine whether IS6110affects phoPpromoter activity in the B strain, we individually cloned the phoPgene and its promoter region (including IS6110from the B strain and the equivalent region from M. tuberculosiswithout IS6110as a control) into a mycobacterial replicative plasmid and transformed M. smegmatiswith the resulting plasmid. Primer extension analysis showed that phoPtranscription was strongly upregulated when the promoter region contained IS6110, as in the case of the B strain. |
| Databáze: |
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