Use of GeneXpert Assay for Diagnosis of Tuberculosis From Body Fluid Specimens, a 2 Years Study

Tuberculosis (TB) remains a major health concern worldwide and India accounts for 23% of the global TB burden. Of all TB cases, extra pulmonary (EP) TB in India accounts for 15 to 20% that remains undetected and untreated not only due to its diverse clinical presentation but also due to lack of diagnostic means. EPTB poses a greater diagnostic challenge in HIV co-infected patients and children. Also with some forms of EPTB like TB meningitis, consequences can be lifethreatening. Early detection of TB and multidrug resistance is a priority in the diagnosis of TB for early disease management. In 2013, the World Health Organization has endorsed the use of GeneXpert MTB/RIF assay, a fullyautomated cartridge based nucleic acid amplification test for the rapid diagnosis of EPTB. We aimed to use the GeneXpert assay on body fluid specimens from patients with strong clinical suspicion, were hospitalized and the microscopic examination was negative for Acid-fast bacilli. GeneXpert assay was performed on 378 body fluid samples that consisted of 164 pleural fluids, 148 CSF, 59 ascitic fluid and 7 other body fluid (synovial, pericardial, peritoneal) specimens. Of these, 32 specimens were positive for MTB with a positivity rate of 10.1%, 8.8% and 9.3% respectively for pleural fluids, CSF and ascitic fluid. Rifampicin resistance was detected in 4 of the pleural fluid and one of the ascitic fluid samples. Collectively, 19.2% of the MTB positives in our study were multidrug resistant (MDR) TB. Thus the results suggest that GeneXpert assay has a good potential in the rapid accurate diagnosis of EPTB especially in body fluids, aids in prompt initiation of appropriate therapy and improving the quality of TB care.