Purpura fulminans secondary to Capnocytophaga canimorsus bacteraemia following a dog bite: A case report and review of literature

INTRODUCTION. Infection due to Capnocytophaga canimorsus may result in a wide variety of clinical presentations. We present a case of life-threatening Capnocytophaga canimorsus infection with evolution of ecchymosis to purpura fulminans. CASE DESCRIPTION. We present a case of a 43-year-old male with a history of excessive alcohol consumption who presented with features of sepsis following a dog bite. This was associated with a striking, widespread purpuric rash. A causative pathogen, C. canimorsus was identified through blood culture and 16S RNA sequencing. His initially purpuric rash underwent bullous transformation and was diagnosed clinically as purpura fulminans, confirmed on skin biopsy. He made a full recovery with prompt antimicrobial therapy, initially with co-amoxiclav but escalated to clindamycin and meropenem due to clinical deterioration and concerns of beta-lactamase resistance. DISCUSSION. β-Lactamase producing Capnocytophaga strains are of increasing concern. This particular concern is reflected in our case as 5 days into treatment with β-lactamase inhibitor combination therapy the patients clinical condition deteriorated but demonstrably improved on switching to a carbapenem. The development of biopsy proven purpura fulminans in this immunocompetent case is a rare severe manifestation of the previously reported manifestation of disseminated intravascular coagulation (DIC) in Capnocytophaga bacteraemia. The case reported describes characteristics common with other DIC presentations such as the presence of clinical risk factors (history of excessive alcohol consumption) and symmetrical involvement. However, an unusual feature in that initial purpuric lesions were followed by the development of a bullous appearance and peripheral necrotic features concerning for purpura fulminans and confirmed with skin biopsy.