Epidemiology of erysipelas and necrotising soft tissue infections

INTRODUCTION. Erysipelas is a common disease in the emergency department, whereas necrotising soft tissue infections (NSTIs) are rare but more severe. The study aimed to investigate the prevalence, incidence, population-based incidence rate, one-year mortality and clinical presentation of erysipelas and NSTIs, and the aetiology, treatment and recurrence of erysipelas. METHODS. This was a population-based cohort study including acute non-trauma patients ≥ 18 years old with erysipelas or NSTIs from the Region of Southern Denmark in the period from 1 January 2016 to 19 March 2018. RESULTS. Among 223,618 acute non-trauma visits, 2,136 had erysipelas (prevalence 1%), and 20 had NSTIs (prevalence 0.01%), 96.7 and 0.89 per 10,000 visits, respectively. The population-based incidence rates were 72.10 per 100,000 person-years for incident cases of erysipelas and 0.94 for NSTIs. One-year mortality was 15% for erysipelas and 25% for NSTIs. Erysipelas and NSTI patients had similar demographics and vital signs. For erysipelas, the predominant pathogen in blood cultures was Streptococcus dysgalactiae, with two-thirds of patients treated with narrow-spectrum penicillin. One-third of the erysipelas patients had a prior hospitalisation for the condition, and 7.7% of incident cases had recurrence within one year. Obesity and liver disease were risk factors for recurrence. CONCLUSIONS. Erysipelas is a common infection in the emergency department, whereas NSTIs are much rarer but also more severe and, at presentation, not distinctive in clinical parameters, which underlines the importance of clinical judgement.