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

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 (PVCs) and IE relapses in a cohort of patients undergoing surgical management. Methods: This is a retrospective, multicenter study of patients with surgical management during the acute course (<42 days) 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 PVCs. Univariate and multivariable analyses showed that preoperative antibiotic duration and pathogens were associated with PVC. The median number of days of preoperative antibiotics was 6.5 (interquartile range [IQR], 4.0-11.0) for patients with PVCs compared to 13.0 (IQR, 8.0-21.0) for those with negative valve cultures (NVCs). In a multivariable model, preoperative antibiotic administration decreased the risk of PVC (odds ratio [OR], 0.85 per day [95% CI, .77-.91]). Enterococcal IE increased the risk of PVC compared to streptococcal IE (OR, 4.16 [95% CI, 1.07-17.48]). Of note, 33 (63.2%) patients with NVCs received a median of 8 (IQR, 5-18.5) days of avoidable intravenous antibiotics per patient. Only 1 IE relapse was identified and occurred in a patient with NVCs. 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.