Time discrepancy for tuberculosis-negative microscopy and culture - the diagnostic gap remains: systematic analysis from a large tertiary care tuberculosis-clinic, Germany 2013-2017

•Open pulmonary tuberculosis patient discharge policy was not reviewed for decades.•After smear-negativity conversion, substantial cultural positivity may remain.•It remains unclear, whether smear-negative patients still may be infective.•The clinical relevance of this finding warrants further investigation.