False rifampicin resistance in Xpert Ultra applied to lymph node aspirate: a case report

A 36-year-old male patient was diagnosed with tuberculosis in Antwerp, Belgium, in May 2018. His lymph node aspirate initially tested rifampicin resistant in Xpert MTB/RIF Ultra, but tested susceptible in all other tests including targeted deep sequencing due to a rare matrix effect in the Xpert MTB/RIF Ultra reaction tube.