Optimal processing of tongue swab samples for Mycobacterium tuberculosis detection by the Xpert MTB/RIF Ultra assay.

and aid liquefaction, sputum must be mixed with Xpert SR prior to transfer into the Xpert Ultra. However, some people under evaluation for TB are unable to produce sputum. Alternative sample types for TB diagnosis would therefore be of value. Oral-swabs, including tongue-swabs have shown promise, but there are technical challenges associated with sample processing. In this study, several new tongue swab processing conditions were evaluated, utilizing SR, either neat or diluted in buffer. The ability of Xpert Ultra to detect TB was improved under these conditions compared with the previously published heat-processing method (1-3), processing steps were simplified, and technical challenges were overcome.