Septic shock and meningitis caused by Capnocytophaga canimorsus (serovar B) in an immunocompetent patient: case report

Background: Capnocytophaga canimorsus, a Gram-negative rod found in the commensal oral microflora of dogs, is a rare cause of infection following a dog bite, with severe infections more commonly occurring in asplenic or immunocompromised patients. This is a rare case of septic shock and meningitis with a serovar B strain in an immunocompetent patient who passed away due to the infection. Case presentation: A previously healthy man in his late 50s with no known immunodeficiencies was admitted to hospital with fever and cognitive deficits after being bitten by a dog. Capnocytophaga canimorsus grew in his cerebrospinal fluid and blood cultures. Despite aggressive fluid therapy, antibiotics and intensive care, the patient succumbed to the infection. The strain was later characterized as serovar B using whole genome sequencing. Conclusions: Even immunocompetent patients are at risk of severe infection caused by Capnocytophaga canimorsus. These infections are an important differential diagnosis in patients presenting with fever following recent dog exposure with serovars A-C being the most common in human clinical isolates.