Differences in the clinical presentation of necrotizing fasciitis depending on the causative pathogen

Necrotizing fasciitis is a fatal, soft tissue infection of the skin that requires prompt treatment. Historically, most cases have been attributed to group A beta-hemolytic Streptococcus infection. However, in recent years, other bacteria have been identified as causing necrotizing fasciitis. In the current study, we analyzed cases of necrotizing fasciitis and examined the significant differences in symptoms caused by pathogenic bacteria. We included 79 patients (43 males and 36 females, mean age 65.4 years) diagnosed with necrotizing fasciitis who visited our hospital between April 2004 and July 2023. The patients were classified into five groups based on the identified pathogen: group A beta-hemolytic Streptococcus; group B beta-hemolytic streptococcus; group G beta-hemolytic Streptococcus; mixed infection, including anaerobic bacteria; and Staphylococcus (S) aureus. The clinical characteristics of patients, including treatment duration and laboratory values, were analyzed. Group G beta-hemolytic Streptococcus was more common in older patients (Bonferroni method, p < 0.05). Patients with S. aureus tended to be hyperglycemic (Bonferroni method, p < 0.05), had a higher rate of bacteremia (Fisher's direct probability test, p < 0.05), and had a longer treatment duration than the other examined groups (Bonferroni method, p = 0.0132). Although the five groups did not differ in the mortality rate, overall survival was shorter in the mixed infection group than in the other groups (log-rank test, p < 0.05). The legs were the most common site of infection in the non-mixed infection group; in the mixed infection group, the pubic area was identified as the most common site of infection, accompanied by a poor prognosis. Collectively, these findings suggest that necrotizing fasciitis can be characterized by pathogenic bacteria and that these characteristics may inversely predict the pathogen of origin.