A Rare Case of Capnocytophaga canimorsus Meningitis in an Immunocompetent Patient: A Successful Outcome with a Short Course of Antibiotics

Abstract

Introduction: Capnocytophaga canimorsus is a Gram-negative bacterium found in the oral flora of dogs and cats, transmitted to humans through bites, licks, or scratches. Infections can lead to severe manifestations, including meningitis, particularly in immunocompromised individuals.

Case presentation: A 46-year-old immunocompetent man presented with somnolence, headache, and fever after being licked by his dog. Neurological examination revealed signs of meningeal irritation, and cerebrospinal fluid analysis showed an elevated white cell count and protein levels consistent with bacterial meningitis. Treatment followed Dutch guidelines with amoxicillin, ceftriaxone, and dexamethasone, resulting in rapid clinical improvement. Microbiological confirmation of C. canimorsus followed later. The patient was treated with antibiotics for the duration of 1 week and remained symptom-free after being discharged.

Conclusion: C. canimorsus meningitis, although rare, poses diagnostic challenges due to its variable presentation and slow growth in culture. Empirical therapy guided by susceptibility testing contributes to favorable outcomes. This case underscores the importance of considering a C. canimorsus infection in patients with animal exposure and of taking diagnostic findings, precedent, and clinical response into account when determining the treatment duration.

Keywords: Antibiotic treatment; Bacterial meningitis; Capnocytophaga canimorsus; Case report; Zoonosis.