Real-time genomics through nanopore sequencing holds the promise of fast antibiotic resistance prediction, but concerns remain about its accuracy. We here show that real-time genomics has the potential to improve clinical practice based on a multi-drug resistant Klebsiella pneumoniae bloodstream infection. In contrast to established diagnostics, real-time genomics can accurately identify complex antibiotic resistance patterns conferred through newly discovered low-abundance resistance genes, potentially significantly impacting clinical decision-making and patient outcome.