# A Fatal Case of Capsular Serovar D of Capnocytophaga canimorsus Infection Following a Dog Bite in a Previously Healthy Adult

## TL;DR

A previously healthy man died rapidly from a rare Capnocytophaga canimorsus infection after a dog bite, likely due to an undiagnosed spleen issue.

## Contribution

This case highlights the rapid progression and fatality of rare C. canimorsus serovar D infection in patients with unrecognized hyposplenism.

## Key findings

- C. canimorsus capsular serovar D was identified post-mortem as the cause of fatal septic shock.
- The patient's unrecognized functional hyposplenism likely contributed to rapid clinical deterioration.
- Systemic symptoms and organ failure occurred within hours of infection presentation.

## Abstract

We report a rapidly fatal case of Capnocytophaga ​​​​canimorsus septic shock with suspected acute infectious purpura fulminans (AIPF) in a 61-year-old man following a dog bite to the finger. Although he appeared previously healthy, retrospective analysis revealed a markedly small spleen (54 mm in diameter) on computed tomography and Howell-Jolly bodies on a peripheral blood smear, indicating unrecognized functional hyposplenism. He developed systemic symptoms within 48 h and progressed to respiratory failure and refractory shock within 1 h of presentation to the emergency department. The blood smear also demonstrated phagocytosed Gram-negative rods, prompting immediate broad-spectrum antimicrobial therapy and intensive care. However, multiple organ failure progressed, and the patient died on hospital day three. C. canimorsus was identified from blood cultures five days after death; capsular serovar D was confirmed subsequently. This case highlights that C. canimorsus infection can trigger explosive clinical deterioration, particularly when uncommon virulent strains like serovar D infect patients with unrecognized splenic atrophy.