Septic Shock Due to Capnocytophaga canimorsus Infection in a Splenectomized Patient

Capnocytophaga canimorsus is a gram-negative rod that is part of the commensal flora of dogs’ mouths. Among splenectomized patients who maintain close contact with dogs, the bacteria can lead to infection and fulminant sepsis even without evidence of a skin breach. In this report, we describe the case of a 71-year-old woman who had undergone splenectomy 35 years ago. She came to our emergency department complaining of back pain, myalgia, asthenia, and a fever of 40.2ºC. No other symptoms were noted upon her admission. Blood workup revealed hyperlacticaemia, increased C-reactive protein, and lymphopenia. A urinalysis and chest radiography were ordered, with no abnormal findings, and the SARS-CoV-2 test was negative. The patient developed persistent hypotension and drowsiness that did not improve with intravenous fluids. Therefore, she was started on a norepinephrine infusion. Cultures were collected, and intravenous antibiotic therapy was started with amoxicillin/clavulanic acid 2.2 mg and azithromycin 500 mg. Besides all the diagnostic tests, no infectious cause was found. On the second day of hospitalization, she started to deteriorate, and antibiotic therapy was escalated to piperacillin/tazobactam 4.5 g, resulting in a good clinical response. On the third day after admission, thanks to a group discussion, we were able to identify C. canimorsus in the patient’s blood cultures. A review of history revealed that the patient was in close contact with her pet dog. This case highlights the importance of a multidisciplinary discussion, including the microbiology team, in order to reach an uncommon diagnosis. When dealing with splenectomized individuals presenting with the septic shock of unclear origin, a history of close contact with dogs must lead clinicians to consider C. canimorsus as a causative agent.