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Capnocytophaga canimorsus, an oral microflora of dogs/cats, is known to cause life-threatening infections following bites, scratches, or close contact in the presence of open wounds. Chronic illnesses and an immunocompromised state further increase the risk. We report a rare case of ventriculitis caused by Capnocytophaga in a dog-owning patient with no visible wounds or reported history of bites or scratches.

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A 78-year-old male with rheumatoid arthritis on rituximab and a history of splenectomy presented to the hospital with syncope. On arrival, he was hypotensive, tachypneic, and tachycardic. Initial labs showed leukocytosis and elevated lactate. He was admitted for sepsis with septic shock, requiring vasopressors, and was empirically started on cefepime and vancomycin. Five days later, blood cultures grew Capnocytophaga. Other infectious workup was unrevealing. He was switched to IV ampicillin-sulbactam and discharged on oral amoxicillin-clavulanate.

Eight days after discharge, the patient was readmitted with worsening fatigue, altered mental status, and fever of 103°F. Empiric IV antibiotics were reinitiated. Blood cultures were negative and there was no evidence of valvular vegetations. Lumbar puncture revealed neutrophilic pleocytosis (WBC count 285), elevated protein (180), and negative PCR and culture. Brain MRI showed diffusion restriction in the bilateral occipital horns without susceptibility or enhancement, concerning for vasculitis. Given these findings, he was restarted on IV ampicillin-sulbactam for presumed ventriculitis in the setting of recent Capnocytophaga bacteremia. Following completion of the IV antibiotic course, the patient showed clinical improvement and repeat MRI revealed resolution of the previous diffusion restriction.

C. canimorsus bacteremia is rare but can lead to life-threatening central nervous system infections following animal exposure, even in the absence of bites or scratches. In immunocompromised individuals with a history of canine contact, differential diagnoses should be considered, as early detection and treatment is essential to reduce morbidity/mortality.