Twenty-Year Experience in the Diagnosis and Treatment of Infective Endocarditis

Risk factors associated with mortality in the infective endocarditis patients requiring cardiac surgery: a study based on Latvian population

BACKGROUND

Increased life expectancy, developments in medicine and intracardiac devices, accessibility of cardiac surgery, decrease in the prevalence of rheumatic heart disease are changing infective endocarditis patient profile and thus risk factors for the adverse events. This single-center-based study covering the whole Latvian population aimed to assess the intrahospital and 3-year mortality of infective endocarditis patients who underwent cardiac surgery, as well as risk factors and laboratory indices predictive of adverse outcomes of the disease.

METHODS

Clinical profiles, data of laboratory and instrumental analyses, operation and intensive care unit records of cardiac surgery patients treated in Pauls Stradins Clinical University Hospital, Riga, Latvia, between 2015 and 2019 were analyzed.

RESULTS

We analyzed data from 242 episodes of surgically treated infective endocarditis in 233 patients. The median age of patients was 57.00 (45.00-68.00) years. The rate of intrahospital mortality was 11.16%. Risk factors associated with mortality in the univariate analyses were S. aureus infection (HR=2.27, 95% CI: 1.36-3.80; P=0.002) and systemic embolization of vegetations (HR=1.63, 95% CI: 1.00-2.64; P=0.048). Perivalvular complications (HR=1.98, 95% CI: 1.19-3.29; P=0.009) were found to be independently associated with mortality in multivariate analysis (HR=1.99, 95% CI: 1.05-3.78; P=0.035). One-year survival was 78.3%, whereas three-year -71.3%.

CONCLUSIONS

Intrahospital mortality of surgically treated IE patients was 11.2%; however, one- and three-year mortality was 21.7 and 28.7%, respectively. Perivalvular complications were independently associated with mortality. Laboratory indices were not predictive of adverse outcomes.

Four decades of experience of prosthetic valve endocarditis reflect a high variety of diverse pathogens

Prosthetic valve endocarditis (PVE) remains a serious condition with a high mortality rate. Precise identification of the PVE-associated pathogen/s and their virulence is essential for successful therapy, and patient survival. The commonly described PVE-associated pathogens are staphylococci, streptococci and enterococci, with Staphylococcus aureus being the most frequently diagnosed species. Furthermore, multi-drug resistance pathogens are increasing in prevalence, and continue to pose new challenges mandating a personalized approach. Blood cultures in combination with echocardiography are the most common methods to diagnose PVE, often being the only indication, it exists. In many cases, the diagnostic strategy recommended in the clinical guidelines does not identify the precise microbial agent and to frequently, false negative blood cultures are reported. Despite the fact that blood culture findings are not always a good indicator of the actual PVE agent in the valve tissue, only a minority of re-operated prostheses are subjected to microbiological diagnostic evaluation. In this review, we focus on the diversity and the complete spectrum of PVE-associated bacterial, fungal and viral pathogens in blood, and prosthetic heart valve, their possible virulence potential, and their challenges in making a microbial diagnosis. We are curious to understand if the unacceptable high mortality of PVE is associated with the high number of negative microbial findings in connection with a possible PVE. Herein, we discuss the possibilities and limits of the diagnostic methods conventionally used and make recommendations for enhanced pathogen identification. We also show possible virulence factors of the most common PVE-associated pathogens and their clinical effects. Based on blood culture, molecular biological diagnostics, and specific valve examination, better derivations for the antibiotic therapy as well as possible preventive intervention can be established in the future.

New insights into valve-related intramural and intracellular bacterial diversity in infective endocarditis

Aims

In infective endocarditis (IE), a severe inflammatory disease of the endocardium with an unchanged incidence and mortality rate over the past decades, only 1% of the cases have been described as polymicrobial infections based on microbiological approaches. The aim of this study was to identify potential biodiversity of bacterial species from infected native and prosthetic valves. Furthermore, we compared the ultrastructural micro-environments to detect the localization and distribution patterns of pathogens in IE.

Material and methods

Using next-generation sequencing (NGS) of 16S rDNA, which allows analysis of the entire bacterial community within a single sample, we investigated the biodiversity of infectious bacterial species from resected native and prosthetic valves in a clinical cohort of 8 IE patients. Furthermore, we investigated the ultrastructural infected valve micro-environment by focused ion beam scanning electron microscopy (FIB-SEM).

Results

Biodiversity was detected in 7 of 8 resected heart valves. This comprised 13 bacterial genera and 16 species. In addition to 11 pathogens already described as being IE related, 5 bacterial species were identified as having a novel association. In contrast, valve and blood culture-based diagnosis revealed only 4 species from 3 bacterial genera and did not show any relevant antibiotic resistance. The antibiotics chosen on this basis for treatment, however, did not cover the bacterial spectra identified by our amplicon sequencing analysis in 4 of 8 cases. In addition to intramural distribution patterns of infective bacteria, intracellular localization with evidence of bacterial immune escape mechanisms was identified.

Conclusion

The high frequency of polymicrobial infections, pathogen diversity, and intracellular persistence of common IE-causing bacteria may provide clues to help explain the persistent and devastating mortality rate observed for IE. Improved bacterial diagnosis by 16S rDNA NGS that increases the ability to tailor antibiotic therapy may result in improved outcomes.