Streptococcus suis endocarditis: prognostic factors and antimicrobial resistance

Streptococcus suis is an important zoonotic pathogen worldwide. This study aims to identify prognostic factors associated with the development of infective endocarditis (IE) and mortality in patients with S. suis bacteremia.

A retrospective cross-sectional study was conducted by reviewing the medical records of patients with culture-confirmed S. suis infection admitted to a tertiary care hospital in Thailand between 2021 and 2023.

Among 200 patients with S. suis bacteremia who underwent echocardiograms, 102 (51%) were diagnosed with IE. Between 2021 and 2023, resistance to penicillin in S. suis increased from 13.0 to 38.7%, while intermediate susceptibility to ceftriaxone rose from 2.2 to 13.3%. Patients with S. suis bacteremia were at higher risk of developing IE if the strains were penicillin-resistant (aPR: 7.94, 95% CI: 1.13-55.80) or if persistent bacteremia was present (aPR: 1.58, 95% CI: 1.27-1.96) in multivariable analysis. Other risk factors included illness duration of more than 14 days (aPR: 2.19, 95% CI: 1.66-2.89) and being under 60 years of age (aPR: 1.42, 95% CI: 1.09-1.83). All-cause in-hospital mortality for patients with S. suis IE was 28.4% (95% CI: 19.9-38.2), higher than that of patients without IE (15.3%, 95% CI: 8.8-24.0). Embolic stroke and acute kidney injury increased the risk of death 3.28-fold (95% CI: 1.82-5.91) and 2.87-fold (95% CI: 1.06-7.79), respectively, after adjusting for confounders.

S. suis is a common cause of IE, particularly among antimicrobial-resistant strains, leading to high morbidity and mortality. Echocardiography is recommended for patients with S. suis bacteremia, although managing drug-resistant infections remains challenging.