Low yield of blood cultures after end-of-therapy of an episode of infective endocarditis: a twelve years’ experience from a referral centre.

Introduction Infective endocarditis (IE) carries a significant risk of recurrence. European clinical guidelines recommend performing follow-up blood cultures (BC), although evidence regarding their utility is limited. We aimed to assess the yield of follow-up BC in these patients. Material and methods Single-centre post-hoc analysis of a prospective cohort including IE survivors diagnosed between 2012 and 2023 with at least 12 months of follow-up. Results Among 225 patients included, follow-up BCs were performed in 153 (68.0%). Recurrence was diagnosed in 19 patients (8.4%). Patients with recurrence had higher mortality during follow-up (15.8% vs 4.4%, p=0.025). Among patients with follow-up BCs, there was one contaminant (0.7%) and, two true positive results (1.3%), both of them representing IE reinfections due to different microorganism. One of them had fever at BC extraction. The one-year recurrence rate and IE-associated mortality (including complications or recurrences) were similar in patients with and without BCs (7.8% vs 9.7%, p=0.789; and 1.4% vs 0.7%, p=0.538, respectively). In the index IE episode, patients with recurrence more frequently presented with previous IE (21.1% vs 5.3%, p=0.035), fungal etiology (10.5% vs 1.5%, p=0.010), and mycotic aneurysms (15.8% vs 1.0%, p=0.004), while they had a lower frequency of native valve (31.6% vs 54.6%, p=0.059) and Staphylococcus aureus (5.3% vs 23.2%, p=0.012). Conclusion Follow-up BCs after an IE episode appears to have low utility, with similar rates of true positives and contaminants. Patients with follow-up BCs did not have more recurrences diagnosed or lower mortality during follow-up.