Abstract
INTRODUCTION: Emergence of drug resistant tuberculosis (TB) has necessitated the development of molecular based rapid diagnostic tests. WHO has approved Genotype MTBDRplus assay for detection of multidrug resistant (MDR) TB.
AIMS: To compare the performance of Genotype MTBDRplus assay with conventional drug susceptibility tests.
METHODS: Total 200 specimens (respiratory [sputum, bronchial lavage], lymph nodes, pleural fluid) were analysed on smear for AFB by ZN stain and Genotype MTBDRplus assay which was done as per manufacturer's instructions. Mycobacterium tuberculosis (MTB) cultures were done by radiometric method. Susceptibility tests were done on L.J. medium.
RESULTS:
1. Overall concordance of Rifampicin (RMP) and isoniazid (INH) results between Genotype MTBDRplus assay and conventional susceptibility results was 95.45% and 93.18% respectively.
2. Genotype MTBDRplus assay positivity in AFB smear negative and smear positive but MTB culture positive respiratory samples was 82.15% and 100% respectively.
| MTB culture (Total 88) | ||||||
| Genotype MTBDRplus assay | Resistant | Susceptible | Sensitivity% | Specificity% | Positive predictive value% | Negative predictive value% |
| RMP | ||||||
| Resistant | 21 | 01 | 87.50 | 98.43 | 95.45 | 95.45 |
| Susceptible | 03 | 63 | ||||
| INH | ||||||
| Resistant | 23 | 05 | 95.83 | 92.18 | 82.14 | 98.33 |
| susceptible | 01 | 59 | ||||
3. Comparison of Genotype MTBDRplus assay with MTB cultures for RMP and INH resistance
CONCLUSIONS:
1. Genotype MTBDRplus assay is sensitive and specific for rapid diagnosis MDR TB .
2. The sensitivity is 100% in AFB smear positive respiratory samples.
3. Even in AFB smear negative pulmonary TB patients, assay is sensitive for diagnosis of MDR TB.
- Copyright ©the authors 2016
