"Sensitivity of GeneXpert Ultra in the Diagnosis of Extrapulmonary Tuberculosis in a Tertiary Hospital Setup of South India”

BACKGROUND: Extrapulmonary tuberculosis (EPTB) poses significant diagnostic challenges due to its varied clinical manifestations and the often paucibacillary nature of the disease. Traditional diagnostic methods, such as smear microscopy and culture, have limited sensitivity, especially in EPTB cases. The GeneXpert MTB/RIF Ultra (Ultra) assay, with its enhanced detection capabilities, offers a potential solution for early and accurate diagnosis. This study evaluates the sensitivity of GeneXpert Ultra in diagnosing EPTB in high-burden, resource-limited settings. METHODS: This Prospective observational study was conducted at a tertiary care center in South Tamil Nadu, involving 52 patients with suspected EPTB, Clinical, radiological, and pathological data were collected, and samples from various EPTB sites were tested using smear microscopy, culture, GeneXpert, and GeneXpert Ultra. The diagnostic yield of GeneXpert Ultra was compared with other methods, and the sensitivity of Ultra was analyzed RESULTS: The study population comprised 28% of patients aged 21-30 years, with a nearly equal gender distribution (53.8% male, 46.2% female). The most common comorbidities were diabetes mellitus (21.2%) and previous pulmonary TB (9.6%). The predominant forms of EPTB were pleural and lymph node TB. GeneXpert Ultra was positive in 38 out of 52 cases (73%), significantly higher than GeneXpert (44.2%), smear microscopy (25%), and culture (26.9%). GeneXpert Ultra also detected trace amounts of MTB DNA in 13.2% of cases, all of which were Rifampicin-sensitive. The assay's high sensitivity highlights its value in diagnosing EPTB, particularly in paucibacillary cases. CONCLUSION: GeneXpert Ultra demonstrated superior sensitivity compared to conventional diagnostic methods for EPTB in this Indian cohort. Its ability to detect low bacterial loads and provide rapid Rifampicin resistance results makes it a critical tool for improving EPTB diagnosis and management, especially in high-burden, resource-limited settings.