ABSTRACT

Introduction: GeneXpert® MTB/RIF Ultra (Ultra) is a method for detecting the Mycobacterium tuberculosis complex (Mtb) with greater sensitivity compared to GeneXpert® MTB/RIF (Xpert). In Brazil, for children and for extrapulmonary tuberculosis (EPTB), "traces detected" results are considered positive for Mtb. Here, we describe the use of Ultra at a reference center for pediatric tuberculosis (TB) in Rio de Janeiro, Brazil. Methods: A cross-sectional study was conducted with children (0-9 years) and adolescents (10-18 years) with presumed EPTB or pulmonary TB (PTB) whose specimens were tested using Ultra. Data were analyzed using descriptive statistics, and Fisher's exact test (significance level p<0.05) was applied when appropriate. The study was approved by the Ethics Committee of IPPMG-UFRJ (CAAE: 02173518.2.0000.5264). Results: Ninety-three patients with presumed TB were included: 44% with PTB and 56% with EPTB. The final diagnoses revealed 63.4% PTB, 40.4% EPTB, and 49.5% other diagnoses. Among the PTB cases, 9/26 (34%) had positive results exclusively by Ultra. As for the EPTB cases, 11/21 (52%) were positive only by Ultra. For PTB, sensitivity was 50% and specificity was 100% (compared to culture). For EPTB, sensitivity was 85.7% and specificity was 100%. Conclusion: Ultra contributed to the diagnosis of both PTB and EPTB, especially in cases with negative culture results. The test demonstrated higher sensitivity in EPTB than in PTB.

Keywords: tuberculosis, real-time PCR, children, adolescents.

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