Streptococcus suis infective endocarditis in patients with Streptococcus suis bacteremia: a retrospective study of prevalence and outcomes.

Background: Streptococcus suis (S. suis) is a zoonotic disease that is transmitted to humans via contact or oral route. Although the major clinical presentation of this pathogen is known to be meningitis, S. suis infective endocarditis (IE) has recently emerged as a clinical manifestation of increasing interest. Echocardiography may be an underutilized modality for evaluating patients with S. suis bacteremia.

Objective: The primary objective was to estimate the prevalence of S. suis IE in patients with S. suis bacteremia. The secondary objective was to investigate the predictors, echocardiographic features, and clinical outcomes of S. suis IE in patients with S. suis bacteremia.

Materials and methods: This single-center retrospective study was conducted at Siriraj Hospital - Thailand's largest university-based tertiary referral center. Adult patients (aged > 18 years) who were admitted to our center with confirmed diagnosis of S. suis bacteremia during January 2007 to September 2023 were included. Prevalence is reported as percentage and confidence interval. Baseline characteristics and clinical manifestation were compared between the IE and non-IE groups. Factors found to be statistically significant were further analyzed using binary logistic regression analysis to identify univariate predictors of S. suis IE.

Result: A total of 71 patients with S. suis bacteremia were included in this study. The prevalence of S. suis IE was 26.8% (95% confidence interval: 17.85-38.05). Perivalvular complications and significant valvular regurgitation were found in 52.6% and 80.0% of patients, respectively. Thirteen of 19 patients (68.4%) required valvular surgery according to standard guidelines. By univariate analysis, dyspnea, new murmur, immunologic phenomenon, and heart failure were predictors of S. suis IE in patients with S. suis bacteremia.

Conclusion: The results of this study revealed a sizable prevalence of S. suis IE in patients with S. suis bacteremia, and there were high rates of both valvular damage and perivalvular complications. Our results strongly suggest that echocardiography may be indicated to evaluate for S. suis IE in patients diagnosed with S. suis bacteremia. Reclassification of S. suis from an atypical organism to a typical organism should be considered.