Seasonal Variation of Group a Streptococcus (GAS) – Related Necrotising Fasciitis Cases in a UK Teaching Hospital

Objectives: Necrotizing fasciitis is a diverse syndrome primarily involving the fascia but also occasionally the overlying skin and underlying muscles. Non-necrotising lower limb cellulitis has been reported to have a marked seasonal variation in our area. We are describing the seasonal variation of our necrotising fasciitis cases. Methods: The medical records of all the patients that were admitted to our institution with a diagnosis of necrotizing fasciitis, from January 1994 to December 2003, were retrospectively reviewed. Results: The necrotising fasciitis infections peaked every year in the spring time, as previously described for cellulitis. The increased incidence was only apparent for group A streptococcus related necrotising fasciitis cases. The diagnosis carried 21% mortality during the same admission. Overall, 39% of the patients had a bad outcome, defined as either death during the same admission, limb amputation or severe disability. 73% of patients who experienced a bad outcome were found to have Group A streptococcus compared to only 41% of the patients in the good outcome group. Conclusions: A seasonal variation was noted for Group A streptococcus associated necrotising fasciitis, that remains a lethal condition. As patients with Group A streptococcus associated necrotising fasciitis tend to have a worse outcome in our series, increased awareness and targeted antibiotic therapy may enhance clinical outcomes. Knowledge of microbiology might also inform infection control decisions.