Localised increase in necrotising fasciitis associated with a shift to monomicrobial aetiology, South Yorkshire, England, 2023

Objectives: An increase in necrotising fasciitis (NF) was observed in South Yorkshire by plastic surgeons. A public health response was established. Methods: Data were collected on NF cases from 2023 and 2019 (control group) from two hospitals in South Yorkshire. Data on demographics, risk factors, co-morbidities and outcome were obtained. Microbiological data were extracted from hospital laboratory information systems. A survey was sent to plastic surgery departments in England to enquire if similar increases had been observed. Results: Data were collected on 33 cases of NF in 2023. Of the 32 cases with ≥1 microorganism isolated, 26 were monomicrobial NF and 6 polymicrobial NF. 9 NF cases were admitted to the hospitals in 2019. Cases in 2023 and 2019 had broadly similar demographics and co-morbidities. NF cases in 2023 were characterised by limb foci, group A streptococcus isolations, and wound infection (chronic, traumatic, or surgical) or ulcer. Case fatality rate for 2023 NF cases was 38% (12/32) compared to 25% (2/8) in 2019. Conclusions: In 2023, we observed a substantial rise in NF in South Yorkshire, characterised by a shift from predominantly Type I NF (polymicrobial) in 2019 to Type II and Type III NF (monomicrobial). The causes of this increase require further investigation and are likely multifactorial.