Unraveling the Risks: Epidemiology of Complicated Pneumococcal Bloodstream Infections

Background Invasive pneumococcal infections, such as bacteremia, remain associated with substantial morbidity and mortality, particularly among individuals with underlying health conditions. The primary objective of this study was to evaluate the association between patient comorbidities, particularly chronic cardiac disease, and the development of complicated pneumococcal bacteremia. Secondary objectives included assessing vaccine coverage and clinical outcomes among high-risk patients. Methods We retrospectively reviewed medical records of patients admitted to SSM Health and St. Louis University Hospitals between 2018 and 2024 with confirmed invasive <i>Streptococcus pneumoniae</i> infection. Data collected included demographics, comorbidities, vaccination status, and clinical presentation. Complicated bacteremia was defined as bacteremia with concurrent invasive organ involvement, including endocarditis, septic arthritis/osteomyelitis, or empyema. Multivariable regression analysis was performed, with statistical significance set at P <0.05. Results Among 153 patients, older age, pre-existing heart disease, and congestive heart failure were significantly associated with complicated bacteremia. Common complications included endocarditis, septic emboli, empyema, and pneumonia. Laboratory markers of disease severity included hypoalbuminemia and leukocytosis. More than half of the patients with complicated bacteremia required intensive care unit admission. Vaccination rates were low among patients who developed complicated bacteremia. Conclusions Older age and pre-existing cardiac disease were key predictors of complicated pneumococcal bacteremia. Despite advances in vaccination and antimicrobial therapy, invasive pneumococcal disease continues to cause significant morbidity and mortality. Understanding the epidemiology and risk factors associated with complicated pneumococcal infections is critical for improving prevention, guiding early recognition, and optimizing patient outcomes.