A Case of Scratched Infection by <i>Capnocytophaga canimorsus</i> Diagnosed Early with Microscopic Peripheral Blood Smear Examination / 日本農村医学会雑誌

ABSTRACT

　　<i>Capnocytophaga canimorsus</i> is a spindle-shaped facultatively anaerobic Gram-negative rod in the oral cavity of dogs and cats. <i>C. canimorsus</i> rarely infects humans through an animal bite or scratch. However, it leads to severe sepsis once infection occurs, and the fatality rate is estimated to be up to 30%. The patient was a 56-year-old man with fatigue and fever. Sepsis with thrombocytopenia was suspected from the blood examination results. We decided to conduct microscopic examination of a non-stained peripheral blood smear and identified bacteria; therefore, Gram stain was immediately performed and spindle-shaped Gram-negative bacilli were detected. Additionally, the patient had a history of a bite and scratch by his cat. We suspected <i>C. canimorsus</i> infection from the microscopic examination findings and history. Moreover, we determined early that the pathogenic bacterium was <i>C. canimorsus</i> by blood culture. With immediate and proper treatment based on these results, we could rescue this septic patient with disseminated intravascular coagulation. Microscopic examination of non-stained peripheral blood smear is helpful for the early diagnosis of <i>C. canimorsus</i> infection.