Necrotizing Fasciitis in Northern Italy: Clinical Characteristics, Risk Factors, and Prognostic Value of the LRINEC...

Necrotizing fasciitis (NF) is a rapidly progressive, life-threatening soft tissue infection characterized by fascial necrosis, with mortality rates of 20-30%. Despite its rarity, NF is increasingly encountered due to the rising prevalence of predisposing factors. Data from Southern European tertiary centers remain scarce.

We retrospectively reviewed all patients ≥18 years with radiological and/or surgical diagnosis of NF managed at IRCCS Policlinico San Matteo, Pavia, Italy, between November 2018 and August 2023. Clinical, microbiological, and treatment data were extracted from electronic medical records. The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score was calculated retrospectively. The Charlson Comorbidity Index was computed for each patient. Given the small sample size, we adopted a purely descriptive analytical approach without inferential testing.

Thirteen patients met inclusion criteria (median age 58 years, IQR 44.5-79.5; 69.2% male). The most common comorbidities were diabetes mellitus (6/13, 46.2%), renal failure (4/13, 30.8%), and chronic liver disease (4/13, 30.8%). The age-adjusted Charlson Index ranged from 0 to 11 (median 4). Lower limbs were the most frequently affected anatomic site (5/13, 38.5%), followed by the perineal/genital region (Fournier gangrene, 4/13, 30.8%). Type II (monomicrobial) NF predominated (9/13, 69.2%). Microbiological cultures were positive in 8/13 patients (61.5%): Gram-positive cocci were isolated in 5/8 (62.5%) and mixed aerobic/anaerobic flora in 3/8 (37.5%). Empirical antibiotic regimens included a piperacillin-tazobactam backbone in 6/12 (50.0%) patients and a meropenem-based combination in 5/12 (41.7%); 6/12 patients underwent targeted de-escalation after culture results. Two patients (15.4%) died in hospital, both with Fournier gangrene and Type I infection (mortality 2/4, 50.0% in Type I vs. 0/9 in Type II). The median length of stay was 26 days (IQR 17-28.5). All patients had LRINEC ≥6 at admission, with 9/13 (69.2%) classified as high risk (≥8).

In this small retrospective Italian cohort, NF was most frequently associated with diabetes and high comorbidity burden. Type I (polymicrobial) infections, predominantly involving the perineal region, showed worse outcomes than Type II infections. The clinical experience accumulated during this study period subsequently informed the development of an institutional empirical antimicrobial protocol for skin and soft tissue infections at our hospital.