Xpert MTB/RIF Ultra outperformed the Xpert assay in tuberculosis lymphadenitis diagnosis: a prospective head-to-head cohort study

Abstract

Objectives: Xpert Mycobacterium tuberculosis/rifampin (MTB/RIF) Ultra (Xpert-Ultra) has shown better sensitivity in comparison with Xpert MTB/RIF (Xpert) in extrapulmonary tuberculosis (TB), whereas the head-to-head comparison of these methods in TB lymphadenitis had barely been performed. Methods: Patients with undiagnosed lymphadenopathy were recruited prospectively and consecutively, and fine-needle aspiration (FNA) biopsy or lymph node tissue was collected. The specimen was subjected to smear, culture, Xpert, and Xpert-Ultra assays. Culture and/or smear for acid-fast bacilli (AFB) or AFB observed on histopathology were performed as a reference. Results: A total of 106 participants were recruited, including 41 confirmed TB, 33 probable TB, and 32 non-TB lymphadenopathies. The head-to-head comparison for MTB detection showed that Xpert-Ultra produced the highest sensitivity when compared with smear, culture, and Xpert (75.7% vs 5.4 %, 13.5%, and 48.7%). When Xpert-Ultra outcomes were integrated for diagnosis, the percentage of confirmed TB lymphadenitis cases increased from 55.4% (41/74) to 85.1% (63/74). The sensitivities of Xpert-Ultra and Xpert on tissue were 73.6% (95% CI: 59.4-84.3) and 39.6% (95% CI: 26.8-54.0), respectively. The sensitivity of Xpert-Ultra on FNA samples (81.0%, 95% CI: 57.4-93.7) was higher than that of Xpert (71.4%, 95% CI: 47.7-87.8). Conclusion: Xpert-Ultra detected significantly more TB lymphadenitis cases than Xpert or culture. This superiority was particularly distinct using lymph node tissue than FNA detection.

Keywords

• Tuberculosis lymphadenitis
• Xpert MTB/RIF Ultra
• Fine-needle aspiration
• Xpert MTB/RIF
• Lymph node tissue