Rapid detection of Rifampicin resistance in sputum samples using indigenously developed molecular probes and comparison with conventional MIC Method.

ObjectiveTo assess the efficacy of indigenously developed molecular probes in detection of rifampicin resistance in Mycobacterium tuberculosis directly in sputum samples and comparison with rifampicin susceptibility by conventional MIC method at 64 mcg/ml. Material and MethodsA total of 81 sputum samples from patients of suspected drug resistant sputum positive for AFB pulmonary tuberculosis were included. All the samples were tested for rifampicin resistance both by MIC method at 64 mcg/ml in LJ media and by indigenously developed molecular probe method simultaneously. ObservationOut of 81 samples,culture on LJ media showed that 48.15% were culture positive while 43.21%were culture negative and 8.64% were contaminated. Rifampicin sensitivity profiles of 28 Mycobacterium tuberulosis isolates with conventional method on LJ media showed that 22 were resistant and 6 were sensitive to rifampicin. Whereas rifampicin sensitivity profiles of 28 Mycobacterium tuberulosis isolates with probe method showed that 21 were resistant to rifampicin while 7 were sensitive to rifampicin. Taking together overall concordance of probe method with conventional method on LJ media at 64mcg/ml is 96.3% and a discordance of 3.7% Conclusion With the concordance of 96.3% our study showed that indigenously developed molecular probes are rapid and accurate methods for detection of rifampicin resistance in Mycobacterium tuberulosis directly in sputum.