THE EXPANDING ROLE OF 16S RIBOSOMAL RNA PCR IN THE MANAGEMENT OF PATIENTS WITH INFECTIVE ENDOCARDITIS UNDERGOING CARDIAC SURGERY

Background and Aim: Molecular tests on blood are effective in identifying the causative organism and they are recommended when blood cultures are negative. However, the role of molecular tests on the surgically excised valve is still unclear. Methods: In this prospective, observational, single center study, we enrolled 100 consecutive patients with infective endocarditis who underwent cardiac surgery between April 2020 and June 2023. Results of preoperative blood cultures (BC), valve culture (VC), 16 s ribosomal RNA and histopathologic analysis of surgical samples were collected. Results: The mean age of the study population was 60±12.5 years. Overall, BC VC and 16srRNA were positive in 83%, 47%, and 76% of cases, respectively. Sensitivity of both valve culture and 16srRNA decreased significantly with prolonged preoperative antibiotic therapy. Of note, 16srRNA was the only positive result in 7% of cases, allowing aetiological diagnosis. In 33% of patients, the VC test was negative while the molecular test was positive. In these cases, histopathological analysis showed acute inflammation in most cases. In 12.5%, the molecular test clarified discrepancies between blood and valve cultures. Conclusions: Molecular test showed higher diagnostic sensitivity than VC, even after 28 days of preoperative antibiotic therapy. Besides identifying the pathogen in 7% of cases with negative culture results, the molecular test demonstrated utility in other crucial situations. When VCs were negative, combining molecular testing and histopathological analysis they allowed the identification of patients who could benefit from prolonged antibiotic therapy. In addition, molecular testing solved discrepancy between blood culture and valve culture results.