A50-14 Barking up the Wrong Valve: Streptococcus Canis and the ICU Tailspin

Abstract Introduction Streptococcus canis (S. Canis), a zoonotic Group G streptococcus commonly found in dogs, is a rare human pathogen. Human infections are typically opportunistic and are associated with soft tissue infections, bacteremia, and mitral valve endocarditis. In immunocompromised hosts, such as patients with cirrhosis or autoimmune disease, these infections may be particularly fulminant, leading to multi-organ system failure and death. We present a case of a 73 year-old immunocompromised male who developed dual-valve endocarditis involving both the natural aortic and mitral valves due to S. canis. This case highlights the severity and potentially fatal trajectory of invasive S. canis infections. Case Presentation A 73-year-old man with a history of alcoholic cirrhosis (MELD 18), pemphigus vulgaris, hypertension, and hyperlipidemia was transferred for coronary artery bypass graft (CABG) evaluation following findings of multivessel coronary artery disease on left heart catheterization. On admission, his labs were notable for severe thrombocytopenia (platelets: 5 × 109/L). Transthoracic Echocardiogram showed an ejection fraction of 30-35% and vegetations on both the native aortic and mitral valves. Blood cultures grew S. canis. The patient and his wife confirmed that he did not suffer an animal bite, but he was in close contact with dogs. Hematology was consulted; immune thrombocytopenia was suspected, and he was treated with IVIG and dexamethasone. CT head for encephalopathy revealed embolic infarcts, which were confirmed on MRI. He then developed hypoxemic respiratory failure, requiring intubation and escalation of vasopressor support. His coagulopathy worsened with rising PT/PTT and decreasing fibrinogen, consistent with DIC; cryoprecipitate was administered. Despite maximal support, he continued to deteriorate and was too unstable to undergo further cardiac procedures. Goals of care were discussed, and he was transitioned to comfort measures. He expired shortly thereafter. Discussion This case illustrates the lethal potential of S. Canis dual-valve endocarditis in vulnerable hosts. Multiple converging factors: cirrhosis-related immune dysfunction, autoimmune disease, thrombocytopenia, embolic phenomena, and cardiogenic/septic shock culminated in a rapidly fatal clinical course. Clinicians should consider zoonotic pathogens in atypical endocarditis cases, especially in the immunocompromised, and remain vigilant for rapid decompensation in such complex presentations. This abstract is funded by: None