[Performance of GeneXpert MTB / RIF in the diagnosis of extrapulmonary tuberculosis in Dakar: 2010-2015].

INTRODUCTION

The challenge facing developing countries is the availability of methods for rapid and accurate diagnosis of tuberculosis. Some molecular techniques offer this advantage, so we used GeneXpert MTB / RIF test in the diagnosis of extra-pulmonary tuberculosis to evaluate its performance compared with conventional methods.

METHODS

Between 2010 and 2015, 544 extrapulmonary clinical specimens were collected and analyzed by microscopy, culture and GeneXpert. The evaluation of antitubercular susceptibility testing was performed using the MGIT 960 system. Genotype MTBDRplus was used to confirm the cases of rifampicin resistance detected by the GX system.

RESULTS

The study population included 544 patients, 55.15% men and 44.85% women. Patients age ranged from 1-92 years with the majority in the 18-45 age group. The sensitivity and the overall specificity of microscopy was 43.86% and 98.36%, 94.74% and 97.95% for GeneXpert respectively (95% CI). There were two discrepant rifampicin-resistant results between GeneXpert test and phenotypic method. Among these cases MTBDRplus test results showed 100% agreement with those of the MGIT 960.

CONCLUSION

This study shows that the GeneXpert test exhibits high sensitivity for routine diagnosis of extra-pulmonary tuberculosis and should be used instead of microscopy. The cases of rifampicin resistance detected by GeneXpert should be confirmed by other molecular testing methods before initiating treatment.