Abstract:
OBJECTIVES: The diagnosis of extrapulmonary tuberculosis (EPTB) is often made on clinical suspicion alone, resulting in both under- and over diagnosis and relatively poor outcomes. In this study, we evaluated the clinical utility of the Xpert MTB/RIF on routinely collected extra-pulmonary specimens in Ethiopia. METHODS: This study was carried out at Jimma University Specialized Hospital, Southwest Ethiopia. Extra-pulmonary specimens were collected from 572 patients clinically suspected of suffering from EPTB. All specimens were tested for TB by smear-microscopy, culture and Xpert MTB/RIF. The diagnostic accuracy of Xpert MTB/RIF was calculated compared to a composite reference standard (CRS), comprising clinical and laboratory results. RESULTS: In total, 572 extra-pulmonary specimens (279 lymph node, 159 pleural, 80 peritoneal, 45 cerebrospinal and 9 pericardial fluids) were tested. The pooled sensitivity and specificity of Xpert MTB/RIF were calculated to be 75% [95% CI: 70-80] and 98% [95% CI: 97-100] respectively when compared to CRS. The highest sensitivity was documented for lymph node specimen (90% [95% CI: 86-94]), moderate sensitivity for cerebrospinal fluid (53% [95% CI: 28-79), while the sensitivity was lowest for pleural (30% [95% CI: 17-44]) and peritoneal (32% [95% CI: 12-51]) fluids. Xpert MTB/RIF in addition detected rifampicin resistance in 13 patients, in perfect agreement with results from line probe assay. CONCLUSIONS: Xpert MTB/RIF may be used as initial diagnostic tool for testing of lymph node specimens from patients suspected of having TB lymphadenitis. The added value of Xpert MTB/RIF to diagnose pleural or peritoneal TB is limited by its poor sensitivity.
