Analytical Optimization of GeneXpert Ultra for Detection of Tuberculosis in CSF Samples

Detection of Mycobacterium tuberculosis complex (MTBC) in extrapulmonary specimens can be challenging due to their paucibacillary nature. This difficulty is especially true for cerebrospinal fluid (CSF), and the low sensitivity and specificity for diagnosis hampers rapid detection and treatment in vulnerable populations. GeneXpert MTB/RIF Ultra has been shown to provide rapid results for detection of MTBC and associated Rifampin resistance, but there is limited data regarding standardized methods for CSF processing on this assay. In this study, we sought to provide guidance regarding the best methods for CSF processing, including optimal volumes to test, length of incubation with sample reagent and finally effects of long-term freezing on detection.