Risk Factors Associated with Positive Intraoperative Valve Tissue Cultures and the Subsequent Impact on Infective Endocarditis Management and Outcomes

Abstract Background Cardiac valve tissue obtained during the surgical management of infective endocarditis (IE) and sent for culture may influence postoperative antibiotic therapy. We sought to identify clinical and microbiologic risk factors associated with positive valve cultures (PVC) and IE relapses in a cohort of patients undergoing surgical management. Methods This is a retrospective, multi-center study of patients with surgical management during the acute (<42 days) course of IE-directed antibiotic therapy. The rate of PVC, IE relapse, and mortality were collected. Univariate and multivariable logistic regressions were performed to identify risk factors associated with PVC. Results Of 113 patients included, 36 (31.9%) had PVC. Univariate and multivariable analyses showed preoperative antibiotic duration and pathogens were associated with PVC. Median (IQR) days of preoperative antibiotics were 6.5 (4.0-11.0) for patients with PVC compared to 13.0 (8.0-21.0) for those with negative valve cultures (NVC). In a multivariable model, preoperative antibiotic administration decreased the risk of PVC (OR 0.85 per day, CI 0.77-0.91). Enterococcal IE increased the risk of PVC compared to streptococcal IE (OR 4.16, CI 1.07-17.48). Of note, 33 (63.2%) patients with NVC received a median (IQR) of 8 (5, 18.5) days of intravenous antibiotics per patient. Only one IE relapse was identified and occurred in a patient with NVC. Conclusions Both preoperative antibiotic duration and causative pathogen were associated with PVC. IE relapses were rare and unrelated to PVC. There may be an opportunity to shorten postoperative antibiotic durations following surgical management in patients with IE.