Beyond the panel: molecular detection is not diagnosis

Over the past decade, molecular diagnostics have become widespread in clinical microbiology, a trend accelerated by the COVID-19 pandemic. Syndromic multiplex PCR panels are increasingly incorporated into routine practice and clinical guidelines, owing to their speed and ease of use. However, their expanding success may overshadow some fundamental principles in bacteriology. In this viewpoint, we argue that the decision to start, continue or stop antibiotics must remain basically clinical; that the detection of nucleic acids is not equivalent to the diagnosis of an infection; and that sample quality, colonization, contamination, off-panel pathogens and prior antibiotic exposure may mitigate the interpretation of molecular results. Available trials show that rapid molecular diagnostics can improve antimicrobial prescribing but their impact on clinical outcomes appears conditional on integration with stewardship programmes. Molecular diagnostics should accelerate and refine clinical reasoning, rather than stand for the key element in the decision to treat bacterial infections.