Purpura fulminans.

CASE PRESENTATION

A 62‐year‐old man was brought to the hospital because of altered mental status associated with fever and an extensive purpuric rash 5 days after a dog bite. He rapidly became hypotensive despite fluid resuscitation, norepinephrine, and broad‐spectrum antibiotic agents (cefotaxime initially then meropenem). Admission laboratory results showed disseminated intravascular coagulation and acute renal failure. Examination of a peripheral blood smear evidenced multiple extracellular and intracellular bacilli, but prolonged blood cultures remained negative despite no prior antibiotic administration (Figure 1). Transthoracic echocardiography revealed a marked reduction in left ventricular contraction. He experienced a brief cardiac arrest, which was successfully resuscitated and led us to place this patient under venoarterial extracorporeal membrane oxygenation (VA‐ECMO) (Figure 2). Patient data were anonymized, and his relatives provided written consent.

FIGURE 1

Intracellular (A) and extracellular (B) bacilli on blood smear at admission (May‐Grunwald‐Giemsa staining, ×1000)

FIGURE 2

Symmetrical extensive purpura fulminans of legs and arms with emerging gangrene of fingers

DIAGNOSIS

Capnocytophaga canimorsus

Finally, 16S rRNA gene sequencing directly from blood allowed the identification of Capnocytophaga canimorsus with >98% sequence similarity. As a result of improving cardiac function, VA‐ECMO was removed 5 days later, and he was weaned off of norepinephrine at day 10.

DISCUSSION

Capnocytophaga canimorsus is a commensal Gram‐negative rod of dog and cat saliva. Bacterial diagnosis is challenging since these pathogens are fastidious facultative anaerobic bacteria. Blood smear microscopy and molecular tools were the cornerstones of this diagnosis. Supportive therapy with ECMO should be considered as a salvage therapy in such a situation.