B69-10 Utility of Xpert XDR/MTB in Xpert MTB/RIF Positive Extra-pulmonary TB (EPTB) Samples: A Step Towards Precision in EPTB Management

Abstract Background EPTB poses difficulties in the optimization of an effective treatment regimen, due to high culture negativity and non-availability of drug susceptibility profile. The emergence of drug-resistant TB, the presence of co-morbidities, or adverse drug reactions (hepatotoxicity) complicates EPTB management. It necessitates testing to ensure comprehensive drug-resistance profiling and optimizing anti-TB therapy. Xpert XDR/MTB, a novel diagnostic tool, extends diagnostic capability by detecting resistance to additional anti-TB drugs. Methods This retrospective study included cases of EPTB in which Xpert MTB/XDR was used as a second-line test following a positive GeneXpert MTB/RIF ultra. The extrapulmonary samples were collected as part of routine diagnostic workflows and subjected to GeneXpert MTB/RIF ultra. Following a positive result, Xpert MTB/XDR testing was performed on the same specimens to detect/characterize additional resistance to other anti-TB drugs. Data were reviewed to assess patterns of resistance and the diagnostic utility of Xpert MTB/XDR in EPTB. Results 19 EPTB cases, whose specimens were subjected to Xpert MTB/XDR, were included. The spectrum of EPTB included Spine TB (8), Lymphadenitis (8; Cervical - 4, Mediastinal - 2, Generalised - 2), pleural TB (2; pleural effusion - 1, pleural nodule - 1), and TB meningitis (1). The type of specimens included tissue (10), pus (7), pleural fluid (1), and CSF (n = 1). Rifampicin resistance was detected in 21.95% (4/19) of cases. Xpert MTB/XDR was positive in 94.7% (18/19) cases. Further, resistance to isoniazid was detected in 11.11% (2/18) cases; fluoroquinolones in 16.67% (3/18) cases, and second-line injectable drugs in 5.5% (1/18) cases. Additional resistance in the absence of rifampicin resistance was detected in one case, i.e., to fluoroquinolones. Xpert MTB/XDR yielded conclusive results in all but one case (Figure 1). Conclusions Xpert MTB/XDR demonstrates the potential as a pivotal tool in enhancing the diagnostic precision for EPTB. The findings underscore the need to evaluate its utility on a large scale and to incorporate it routinely in EPTB diagnostics. This abstract is funded by: None