Detection of Mycobacterium tuberculosis in paucibacillary sputum: performances of the Xpert MTB/RIF ultra compared to the Xpert MTB/RIF, and IS6110 PCR

P. Kolia-Diafouka (1) , S. Carrere-Kremer (1) , M. Lounnas (1, 2) , A. Bourdin (3, 1) , Laurent Kremer (4) , P. van de Perre (1) , S. Godreuil (2) , E. Tuaillon (1)

1 CHRU Montpellier - Centre Hospitalier Régional Universitaire [Montpellier]
2 IRD - Institut de Recherche pour le Développement
3 PhyMedExp - Physiologie & médecine expérimentale du Cœur et des Muscles [U 1046]
4 IRIM - Institut de Recherche en Infectiologie de Montpellier

The Xpert MTB/RIF Ultra assay has recently been launched to improve the detection of smear negative disease. This retrospective study compares the sensitivity of Xpert MTB/RIF Ultra with that of Xpert MTB/RIF tests and IS6110 real-time PCR in sputum. Diagnostic performance of three molecular tests was evaluated using 48 culture-positive clinical respiratory specimens diluted to obtain paucibacillary sputum specimens. Xpert MTB/RIF Ultra had the highest sensitivity of 100% compared to 42% (P < 0.001) for Xpert MTB/RIF and 64.5% (P = 0.02) for IS6110-PCR. All "very low" or "low" positive specimens using Xpert MTB/RIF Ultra were tested positive using IS6110-PCR, but 35.4% were found negative using Xpert MTB/RIF. Xpert MTB/RIF Ultra is more sensitive than the two other tests for sputum with a low bacterial load. Adding detection of IS6110 and IS1081 to rpoB, is a key evolution of the assay and improves the detection of Mycobacterium tuberculosis' DNA in paucibacillary sputum.

Mots clés: Chelex®; IS6110-PCR; Mycobacterium tuberculosis; Paucibacillary sputum; Xpert MTB/RIF; Xpert MTB/RIF ultra

Domaines: Sciences du Vivant [q-bio]

P. Kolia-Diafouka, S. Carrere-Kremer, M. Lounnas, A. Bourdin, Laurent Kremer, et al.. Detection of Mycobacterium tuberculosis in paucibacillary sputum: performances of the Xpert MTB/RIF ultra compared to the Xpert MTB/RIF, and IS6110 PCR. Diagnostic Microbiology and Infectious Disease, 2019, ⟨10.1016/j.diagmicrobio.2019.02.008⟩. ⟨hal-02105943⟩