Microbiological findings in infective endocarditis, event predictor and prognostic value

Funding Acknowledgements None. Introduction In infective endocarditis, microbial isolation can be related to the prognosis of the disease. Identify the cause of endocarditis can help decide further management appropriate. Our purpose was to evaluate the most frequent microbiological findings in our healthcare area, as well as their association with prognostic determinants. Material and Methods Retrospective, observational, single-center study*. Based on a registry of patients diagnosed with infective endocarditis during the years 2016-2022 in a reference hospital with cardiac surgery. Patients with infective endocarditis were analyzed according to their type of microbial isolation, observing the microbial epidemiology and comparing these groups according to their baseline characteristics (age, sex, risk factors), the different therapeutic management in each group (type of antibiotic treatment used, surgical intervention, surgical indication etc.) and compared the groups according to the frequency of different prognostic determinants and events (Reinfection, Embolism, Shock, Mortality, local complications, etc.). To analyze the differences in events between different groups of microorganisms, the Chi square statistic of Homogeneity was used, and a significance level of p<0.05 was established. Results 162 patients were analyzed for an average of 66 years. The rate of positive blood cultures was 93%. The most frequently isolated microorganisms were, Figure 1. Patients who suffered from S. aureus endocarditis (with a mean age also of 66±10 years) had a higher prevalence of pacemaker infections and were complicated by septic shock more frequently (43%, p<0.01) than patients with other types of microorganism isolation. However, we did not have high surgery rates, and we did not observe significant differences in terms of recurrence or mortality, despite being a very virulent microorganism. On the other hand, S.Epidermidis (which is associated with early prosthetic valve endocarditis) is the microorganism most closely related with abscesses, fistulas or other perivalvular involvements (34%, p=0.04), in relation to endocarditis after valve surgery. This group also appears to have a greater tendency, although not significant, to cause AV blocks. Furthermore, S.Epidermidis was the group of patients that most frequently underwent surgery (62% p<0.001) Figure 2. Conclusions In this study, we have observed a higher frequency of isolation of E. feacalis, with significant differences in comparison to other series, and a significantly higher number of recurrences in comparison to other microorganisms. S. aureus is the microorganism most linked to shock, but it is also the one with the lowest number of undergone surgeries, despite being comparable populations. In valve prosthetic endocarditis, S. epidermidis was the most frequent pathogen isolated, and was more frequently associated with perivalvular involvement and the need for surgery.