Caracterización clínica y microbiológica de pacientes con trazas en Xpert MTB/RIF Ultra

Abstract

Introduction: Xpert MTB/RIF Ultra has dramatically changed the diagnosis of tuberculosis. A new category called traces appeared, which is the smallest amount of bacillar load detectable. Ob- jective: Describe the clinical characteristics of patients that present traces in Xpert MTB/RIF Ultra test, and to evaluate the confirmation of tuberculosis as clinical diagnosis. Methods: We perform a descriptive case series study. Information was recovered from clinical records of patients with positive test for traces. Clinical, histopathological and microbiological results were confronted. Results: Twenty one patients were analyzed. The mean age was 52 years-old. All cases had negative smear microscopy and four MGIT cultures were positive, two in pleural fluid and another in sputum. In parietal pleura, three cases presented granulomas with caseous necrosis, and one showed granuloma with very little necrosis. In pleural tissue we observed two cases of granulomas with traces of necrosis and two with non-necrotizing granulomas. Three patients had history of previous tuberculosis and positive traces, the test was interpreted as a false positive result. Finally, active tuberculosis was diagnosed in 13 cases, and five of them were pleural tuberculosis. The highest clinical, microbiological and histopathological agreement was in fluid and pleural tissue samples. Discussion: The findings of Xpert MTB/RIF Ultra in airway samples must be interpreted carefully. Multi-disciplinary analysis is crucial in future clinical decisions. The finding of traces in pleura has, in our opinion, a high diagnostic value in the study of tuberculosis in this location.

La mayor concordancia clínica, microbiológica e histopatológica fue en muestras de líquido y tejido pleural. Discusión: Se debe interpretar con cautela los hallazgos de esta prueba en muestras de vía aérea; el análisis multidisciplinario (clínica, imágenes, microbiología, histología) es crucial en las de­cisiones de nuestras conductas clínicas futuras. El hallazgo de trazas en pleura tiene, a nuestro parecer, un alto valor diagnóstico en el estudio de la tuberculosis en esta localización.