Improving timelines in reporting results from positive blood cultures: simulation of impact of rapid identification on therapy on a real-life cohort

For patients with bloodstream infections, rapid initiation of the appropriate antimicrobial therapy is essential in reducing mortality and morbidity. New developments and automation in clinical microbiology labs speed up the identification and susceptibility results but are expensive. To gain insight in the added value of the new workflows, we simulated the possible impact of rapid identification and susceptibility tests on a real-life cohort of 158 positive blood culture episodes. Our routine workflow was theoretically challenged against two new workflows, one based on rapid identification with MALDI-TOF MS and one based on molecular testing. First, we observed an important role of the rapid communication of the gram stain results, as about one third of patients needed an adaptation of the antimicrobial therapy based on these results. Antibiotic adaptation based on the microorganism identification was necessary in 10% and in another 25% of cases after the availability of the susceptibility results. The added value of the newer workflow methods lies mainly in the field of the rapid identification and was rather limited in our cohort. In conclusion, for optimizing the blood culture workflow, each microbiology lab should critically scan its own workflow and know its own blood culture epidemiology, before investing in expensive or time-consuming processes.