Contribution of Gene-Xpert in the Diagnosis of Negative Microscopy Pulmonary Tuberculosis in Brazzaville, Republic of Congo

Abstract

Setting: Xpert MTB/Rif has become an integral part of tuberculosis diagnostic algorithms in many low- and middle-income countries and no published data was retrieved regarding the diagnostic accuracy of Xpert MTB/RIF in sputum smear-negative pulmonary TB in RoC.

Objectives: This study aimed at determining the diagnostic accuracy of Xpert MTB/RIF in diagnosing sputum smear-negative pulmonary tuberculosis keeping AFB microscopy as the gold standard.

Design: For 4 months, one morning sputum smear was performed for every TB suspect (cough lasting >3 weeks, as defined in Congolese’s national guidelines) with AFB microscopy and GeneXpert.

Results: Of 90 TB suspects for whom AFB microscopy and GeneXpert were performed, 79 (87.78%) sputum smear-negative 17 (21.52%) GeneXpert positive cases were identified. During the study, 11 (12.22%) sputum smear-positive cases were diagnosed. GeneXpert has greatly contributed to increasing the total number of bacteriologically proven cases.

Conclusion: These results confirms the utility of GeneXpert in the diagnosis of tuberculosis especially smear negative pulmonary tuberculosis, and demonstrates that the expected number of smear-negative TB cases in Republic of Congo is probably much higher than the World Health Organization’s current annual estimates.