Microbiological Characteristics of Necrotizing Fasciitis at Sultan Qaboos University Hospital, Muscat, Oman: A Retrospective Study

Introduction Necrotizing fasciitis is a life-threatening, rapidly progressing infection of the subcutaneous tissue and fascia. Diabetes mellitus, immunosuppression, and other comorbid conditions are primary predisposing factors. The lower limbs are the most commonly affected site. Necrotizing fasciitis is classified into two main microbiological categories: type I (polymicrobial infection), which is more prevalent, and type II (monomicrobial infection). Early clinical recognition, prompt surgical debridement, and timely initiation of appropriate empirical antimicrobial therapy are crucial for effective management. Methods A retrospective study was conducted over a five-year period (2015-2021), including adult patients (≥18 years) with a confirmed diagnosis of necrotizing fasciitis who had available clinical data and a follow-up period of 12 months. Clinical parameters, including comorbid conditions, infection sites, and management approaches (surgical and medical), were documented. Additionally, microbiological profiles and antimicrobial resistance patterns were analysed to determine their impact on 30-day mortality. Results A total of 43 patients were included, with 31 males (72%) and 12 females (28%), and a median age of 61 years (range: 18-85 years). Diabetes mellitus was the most prevalent comorbid condition, affecting 31 patients (72%). Lower limbs were involved in 31 cases (72%). Type I and type II infections were nearly equally distributed, accounting for 22 cases (51%) and 21 cases (49%), respectively. The predominant isolated organisms were Pseudomonas aeruginosa in four cases (9%), Escherichia coli in four cases (9%), Klebsiella pneumoniae in three cases (7%), methicillin-resistant Staphylococcus aureus (MRSA) in three cases (7%), and Proteus mirabilis in three cases (7%). Extended-spectrum β-lactamase-producing organisms were identified in two cases (5%). Multidrug-resistant (MDR) Pseudomonas aeruginosa was found in four cases (9%), MDR Klebsiella pneumoniae in three cases (7%), and MDR Acinetobacter species in two cases (5%). The total prevalence of MDR organisms was eight cases (19%). The 30-day mortality rate was recorded in three patients (7%). Conclusion Necrotizing fasciitis was more prevalent among males, with diabetes mellitus identified as the leading predisposing factor. The lower limbs were the most commonly affected site, with nearly equal distribution of type I and type II infections. Gram-negative and MDR organisms were common, though MDR infections were not significantly associated with mortality. Early diagnosis, timely surgical intervention, and targeted antimicrobial therapy likely contributed to the low mortality rate (7%). Emphasising the need for regional-specific resistance patterns and antimicrobial strategies.