The relationship between causative microorganisms and cardiac lesions caused by infective endocarditis: New perspectives from the contemporary cohort of patients

Background: The etiology of infective endocarditis (IE) is changing. More aggressive forms with multiple IE cardiac lesions have become more frequent. This study sought to explore the relationship between contemporary causative microorganisms and IE cardiac lesions and to analyze the impact of multiple lesions on treatment choice.

Methods: In 246 patients hospitalized for IE between 2008 and 2015, cardiac lesions caused by IE were analyzed by echocardiography, classified according to the 2015 European Society of Cardiology guidelines and correlated with microbiological data. We defined a new parameter, the Echo IE Sum, to summarize all IE cardiac lesions in a single patient, enabling comprehensive comparisons between different etiologies and treatment strategies.

Results: Staphylococcus aureus was associated with the development of large vegetation (OR 2.442; 95% CI 1.220-4.889; p=0.012), non-HACEK bacteria with large vegetation (OR 13.662; 95% CI 2.801-66.639; p=0.001), perivalvular abscess or perivalvular pseudoaneurysm (OR 5.283; 95% CI 1.069-26.096; p=0.041), and coagulase-negative staphylococci (CoNS) with leaflet abscess or aneurysm (OR 3.451; 95% CI 1.285-9.266, p=0.014), and perivalvular abscess or perivalvular pseudoaneurysm (OR 4.290; 95% CI 1.583-11.627; p=0.004). The Echo IE Sum significantly differed between different etiologies (p<0.001), with the highest value in non-HACEK and the lowest in streptococcal endocarditis. Patients operated for IE had a significantly higher Echo IE Sum vs those who were medically treated (p<0.001).

Conclusion: None of the IE cardiac lesions is microorganism-specific. However, more severe lesions were caused by S. aureus, CoNS, and non-HACEK bacteria. The highest propensity to develop multiple lesions was shown by the non-HACEK group. Higher Echo IE Sum in patients sent to surgery emphasized the importance of multiple IE cardiac lesions on treatment choice and potential usage of Echo IE Sum in patient management.