Surviving Capnocytophaga Canimorsus Septic Shock: Intertwining a Challenging Diagnosis with Prompt Treatment

Capnocytophaga canimorsus is zoonotic agent isolated from humans bitten by dogs or cats. Although rare, severe infection usually affects male patients over the age of 50, asplenic or immunocompromised. Diagnosis is often challenging, often missing a history of contact with dogs or pre-existing wounds. Mortality rate is extremely high, since infection can lead to fulminant sepsis. We report a case of a patient admitted to ED for septic shock of unknown origin. Severe sepsis developed since our patient was asplenic and possessed multiple comorbidities. Due to hypoxia and respiratory failure, the patient was promptly intubated and mechanically ventilated. Supportive treatment for hemodynamic shock was administered. Cultures were obtained in the ED and empiric antibiotic therapy with piperacillin/tazobactam was started, aiming at infection control. As for source identification, common infectious etiologies, SARS-CoV-2 swab, bronchoalveolar lavage and urine cultures were negative. Blood cultures proved Gram-negative rods after 12 h incubation and C. canimorsus was identified on day 4. During ICU stay, clinical conditions gradually improved, and source control proved to be effective. Culture samples collection and starting empiric antibiotic treatment are the essential points in ensuring patient survival, especially in sepsis or septic shock of unknown origin or uncommon etiology, as in our case. Why should an emergency physician be aware of this? C. canimorsus bacteremia is rare and difficult to diagnose. Although considering patient history in such cases is crucial, laboratory results are often delayed. Hence, the chance of survival is dependent on prompt culture samples collection and start of empiric antibiotic treatment, along with supportive treatment.