11/04/2026
Important read….
This case describes an 80-year-old woman who developed rapidly progressive and fatal sepsis due to Capnocytophaga following a minor dog bite.
Capnocytophaga canimorsus is a type of bacteria commonly found in the mouths of dogs and cats. It can be transmitted to humans through bites, scratches, or even saliva contacting broken skin. In most cases, it does not cause serious illness—but in rare situations, it can spread rapidly into the bloodstream and lead to severe infection (sepsis).
She initially presented with a 2-day history of fever, abdominal pain, and altered mental status. On arrival, she was still alert, but her condition rapidly worsened—she became drowsy, hypoxic, and developed mottled skin changes consistent with purpura fulminans. Despite aggressive treatment, her condition progressed to refractory septic shock.
Although severe infection is more commonly seen in individuals with liver disease, immunosuppression, chronic illness, or advanced age, this patient had no clear predisposing conditions aside from being elderly. Age-related decline in immune function (immunosenescence) likely contributed to her susceptibility and the severity of disease.
Importantly, this case highlights how dog bites are often underestimated. The patient sought medical care and received antibiotics three days after the bite and at least two days after early signs of infection had already developed. This delay, combined with the virulence of C. canimorsus, likely contributed to the rapid progression to multiorgan dysfunction and septic shock.
Diagnosis of C. canimorsus can be challenging due to its slow growth in standard cultures. On microscopy, it appears as Gram-negative, fusiform rods, and more advanced techniques such as PCR and 16S rRNA sequencing are often required for definitive identification.
Key takeaway: Dog bites should never be underestimated. Even minor wounds can lead to severe, life-threatening infections. Early recognition and prompt initiation of antibiotics are critical.
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Mantovani, Elena, Busani, Stefano, Biagioni, Emanuela, Venturelli, Claudia, Serio, Lucia, Girardis, Massimo, Purpura Fulminans and Septic Shock due to Capnocytophaga Canimorsus after Dog Bite: A Case Report and Review of the Literature, Case Reports in Critical Care, 2018, 7090268, 3 pages, 2018.
