A50-13 Unveiled by Sepsis: Functional Hyposplenia Exposed by Capnocytophaga

Abstract Introduction Capnocytophaga canimorsus is a fastidious, gram-negative bacillus found in the oral flora of dogs and cats. Human infections are rare but may progress rapidly to fulminant septic shock, particularly in individuals with immunocompromise, asplenia, or alcohol use. These cases often present with disseminated intravascular coagulation (DIC), multi-organ failure, or peripheral gangrene, with high mortality. We report a case of fulminant C. canimorsus septic shock in a woman initially presumed healthy, whose infection revealed previously unrecognized functional hyposplenism. Case presentation A 71-year-old woman with no significant medical history presented with abdominal pain and dyspnea, found to be in septic shock with multiorgan failure requiring intubation, vasopressors, and dialysis. She lived in the San Francisco Bay Area, frequently hiked with her dog, and had recently traveled to southern Africa. Weeks after returning, she sustained a lip injury from a caulking gun with persistent rash. Empiric antibiotics (cefepime, vancomycin, Zosyn) were escalated to meropenem, micafungin, and doxycycline, with continuation of vancomycin. CT imaging showed diffuse colitis, hepatomegaly, adrenal enlargement, and splenic atrophy. Despite cholecystostomy for presumed acalculous cholecystitis, she developed DIC with intracranial hemorrhages and ischemic digits. A Karius test identified C. canimorsus; therapy was narrowed to meropenem. She gradually improved and was discharged to rehabilitation for therapy completion and evaluation of ischemic digits. Discussion This case underscores the diagnostic challenges of fulminant sepsis in an apparently healthy patient with risk factors including dog exposure, recent vaccinated travel, and lip injury. Blood cultures and a Karius plasma microbial cell-free DNA test identified Capnocytophaga canimorsus, a rare pathogen (0.5-0.7 cases per million per year). Rapid molecular diagnosis enabled timely therapy optimization. As part of normal oral flora of dogs and cats, C. canimorsus is transmitted via bites, scratches, or close contact and primarily affects individuals with immunodeficiency, asplenia, or alcohol use. In this patient, lip injury and unrecognized hyposplenism likely predisposed her to infection from her dog. Severe Capnocytophaga sepsis illustrates how silent splenic dysfunction can remain undetected until revealed by infection. Recognition of hyposplenism has key implications for care, including evaluation for causes and preventive strategies. Vaccination against encapsulated organisms, education on seeking prompt care for febrile illness, and antibiotic prophylaxis are vital to long-term management. Conclusion Uncommon pathogens such as Capnocytophaga can exploit hidden vulnerabilities, turning a silent condition into fulminant sepsis. Identifying hyposplenism clarified disease severity and enabled preventive strategies to reduce future risk. This abstract is funded by: None