Xpert MTB/XDR: a 10-Color Reflex Assay Suitable for Point-of-Care Settings To Detect Isoniazid, Fluoroquinolone, and Second-Line-Injectable-Drug Resistance Directly from Mycobacterium tuberculosis-Positive Sputum

Authors: Yuan Cao, Heta Parmar, Rajiv L. Gaur, Deanna Lieu, Shobana Raghunath, Nova Via, Simone Battaglia, Daniela María Cirillo, Claudia M. Denkinger, Sophia B. Georghiou, Robert Kwiatkowski, David H. Persing, David Alland, Soumitesh Chakravorty - Journal of Clinical Microbiology 2020 cited by 101

patterns generated by the SMB probes. The assay has a limit of detection comparable to that of the Xpert MTB/RIF assay and successfully detected 16 clinically significant mutations in a challenge set of clinical isolate DNA. In a clinical study performed at two sites with 100 sputum and 214 clinical isolates, the assay showed a sensitivity of 94% to 100% and a specificity of 100% for all drugs except for ETH compared to that of sequencing. The sensitivity and specificity were in the same ranges as those of phenotypic drug-susceptibility testing. Used in combination with a primary tuberculosis diagnostic test, this assay should expand the capacity for detection of drug-resistant tuberculosis near the point of care.