9 February 2009 – Tuberculosis Week
2009 FEB 9 – (NewsRx.com) — According to recent research from Karachi, Pakistan, “Pakistan ranks eighth globally among TB burden countries, with a MDR rate of 2-5%. The most prevalent MTB genotype is Central Asian Strain1 (CAS1) followed by the Beijing genogroup.”
“We investigated common mutations in multidrug resistance encoding genes rpoB, katG and inhA of CAS1 and Beijing strains using DNA sequencing and fluorescent resonance energy transfer (FRET) probe based real-time PCR methods. 30 CAS1, 12 Beijing and 20 unclustered spoligotypes, and 10 susceptible MTB strains were tested. The most common mutations in the rpoB gene were at codons 531 (60%), 526 (23%) and 516 (5%). CAS1 strains had a higher frequency of mutations at codon 526 (p <0.001), with more concurrent mutations (p <0.05) compared with Beijing and orphan types. Mutations at codon 315 of the katG gene were higher in CAS1 than Beijing strains (p = 0.052). Only 1/62 MDR strain, which belonged to CAS1, had a mutation in the inhA gene. Sensitivity and specificity of probe based assay was 93% and 100% for rpoB, and 95% and 100% for katG, respectively,” wrote A. Ali and colleagues, Aga Khan University.
The researchers concluded: “The FRET probes method detected 84% and 60% of rpoB and katG mutations and can therefore be used as a rapid method of screening MTB strains including CAS1.”
Ali and colleagues published their study in Scandinavian Journal of Infectious Diseases (M. tuberculosis Central Assian Strain 1 MDR isolates have more mutations in rpoB and katG genes compared with other genotypes. Scandinavian Journal of Infectious Diseases, 2009;41(1):37-44).
For additional information, contact R. Hasan, Aga Khan University, Dept. of Pathology & Microbiology, Stadium Rd., POB 3500, Karachi 74800, Pakistan.
Publisher contact information for the Scandinavian Journal of Infectious Diseases is: Taylor & Francis as, Karl Johans Gate 5, NO-0154 Oslo, Norway.
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