Fatal septic shock caused by Capnocytophaga canimorsus diagnosed by 16S rRNA gene sequencing

Introduction: Capnocytophaga canimorsus is a commensal bacterium found in the saliva of dogs and cats. In most cases C. canimorsus causes local infection resulting from bite-wounds, scratches or licks but severe forms can occur. The following case describes a severe and rapidly fatal sepsis and disseminated intravascular coagulation with no evidence of bite in a patient without obvious cause of immunosuppression, diagnosed by polymerase chain reaction and 16S rRNA gene sequencing.

Case report: Herein we present a rare case of a 39-year-old man who was taken care of by the emergency medical service for faintness, fever and chills associated with generalized mottling. Despite critical care management and broad-spectrum antibiotherapy, the patient presented an irrepressible shock with disseminated intravascular coagulation and multiple organ failure. He died during the night. The initial etiological assessment was negative but rod-shaped inclusions could be observed in his blood. A pan-bacterial polymerase chain reaction targeting part of the gene encoding 16S ribosomal ribonucleic acid (rRNA) was carried out directly on blood cultures; the sequencing identified Capnocytophaga canimorsus.

Conclusions: This observation illustrates the potential severity of C. canimorsus infection even in a patient without neither obvious causes of immunosuppression nor evidence of bite. The presence of intracellular bacillary forms on the blood smear is an important information which should lead to performing a polymerase chain reaction and 16S rRNA gene sequencing.