Bartonella Infection and Streptococcus constellatus Infective Endocarditis Complicated with Cardiac Arrest: A Case Report and Literature Review.

Background: Infective endocarditis (IE) is a severe infectious disease affecting the endocardium and cardiac valves, caused by various pathogens. Among numerous pathogenic microorganisms, Staphylococcus aureus is the most common, followed by other streptococci such as Streptococcus viridans and enterococci. Bartonella, a Gram-negative, fastidious parasitic bacillus, is a rare causative agent of IE Streptococcus constellatus, belonging to the Streptococcus milleri group, commonly colonizes oral cavity, upper respiratory tract, and gastrointestinal tract, which can cause infections when host immunity is impaired. This study demonstrates a surviving case of infective endocarditis caused by Streptococcus constellatus, initially illustrating cardiac arrest and Bartonella infection. Case Presentation: A 59-year-old male with a history of Bartonella infection post-cat scratch presented progressive vision loss and dyspnea. Admitted to the emergency department, he suffered sudden cardiac arrest, necessitating CPR and intubation before transferring to the ICU. Multidisciplinary evaluation confirmed infective endocarditis (IE), and he was implemented a successful valve replacement surgery. Pathogen identification via high-throughput sequencing of valve tissue revealed Streptococcus constellatus. The patient received targeted anti-infective therapy, mechanical ventilation, and cardiopulmonary support, laying solid foundations for successful extubation and transfer for further specialized care. Conclusion: Bartonella and Streptococcus are rare etiologies of infective endocarditis. This case underscores the vital role of intensive care in managing infective endocarditis resulted from cardiac arrest, as well as the challenges and significance of a multidisciplinary approach to such complex conditions. Furthermore, it highlights the critical utility of high-throughput sequencing in pathogen identification and guiding antimicrobial therapy optimization.