When the results were further stratified by previous tuberculosis history (table 2), reclassification of trace Ultra results as negative resulted in a decrement in Ultra-Sp2-pellet sensitivity from 92·1% (70 of 76; 83·8 to 96·3) to 77·6% (59 of 76; 67·1 to 85·5), whereas Ultra-Sp1-raw sensitivity was less affected. Here, SP1 is linked to tuberculosis.