TB drug resistance PCR
These assays are available following discussion with a Microbiology Consultant or Specialist Clinical Scientist. They are useful for the rapid prediction of drug resistance in samples from patients with risk factors associated with drug resistance (e.g. contact with a known case of MDR-TB, born/previously resident of a country with high prevalence of MDR-TB, previously treated for tuberculosis). They may also be appropriate in cases where co-morbidities may complicate the choice of suitable anti-tuberculous drugs
|Various sample types
|Drug resistance in M.tuberculosis is frequently associated with mutations in specific genes. PCR amplification of these regions and subsequent detection of mutations using a line probe assay provides a method of predicting resistance which is more rapid than phenotypic methods. Tests are available for the detection of markers of resistance to rifampicin and isoniazid using the GenoType MTBDRplus assay (Hain Life Science) and for second line agents fluoroquinolones, aminoglycosides and cyclic peptides using the GenoType MTBDRsl assay (Hain LifeScience).
A negative result does not rule out drug resistance because not all mechanisms for resistance for the different drugs are known. Approximately 95% of rifampicin resistant strains and 80% of isoniazid resistant strains are detected by the MTBDRplus assay. Approximately 60-80% resistant strains for second line agents are detected by the MTBDRsl assay. All genotypic results should be confirmed by phenotypic testing following mycobacterial culture.
|LGI Microbiology Department
|IP Routine TAT
|GP Routine TAT