4. Necrotising fasciitis in the northern territory of australia

Abstract

Background Necrotising fasciitis is a severe, rapidly destructive soft tissue infection characterised by widespread fascial necrosis. Its estimated incidence is 3.5 cases per 100,000 persons, with a case-fatality rate of 24%. Traditional microbiological classification includes polymicrobial infections involving anaerobic bacteria and non-serogroup A streptococci (Type I), and Streptococcus pyogenes with or without Staphylococcus species (Type II). Aims To determine the morphological and microbiological characteristics of necrotising fasciitis in the Northern Territory. Methods In the Northern Territory between January 2000 and December 2012 there were 84 cases of necrotising fasciitis. Histological diagnosis was made according to the presence of necrosis of the superficial fascia, with or without neutrophilic infiltrates or bacteria, and oedema of the reticular dermis, subcutaneous fat and superficial fascia. Patient demographics and microbiological results were collated. Results and conclusions The average age of patients with necrotising fasciitis was 48.9 years. There was a male predominance, and Indigenous patients accounted for 49% of cases. Sites affected, in descending frequency, were lower limbs, upper limbs and torso, head/neck and scrotum/perineum. Despite prompt antimicrobial therapy and surgical intervention, 10% of patients required limb amputation and 25% of patients died from their disease, with almost half being Indigenous. Tissue reaction patterns were similar to those described in the literature, initially involving the superficial fascia followed by extension to both superficial and deep structures with disease progression. Interestingly, our data highlights deviation from the traditional microbiological classification. We demonstrated a high prevalence of pure growths of Staphylococcus (20%) and Pseu-domonas (4.7%). Remarkably, fungal isolates were also relatively prevalent. Our findings confirm necrotising fasciitis is a devastating infection associated with high morbidity and mortality. Despite morphological similarities of necrotising fasciitis, data from the Northern Territory portrays unique microbiological variation in its causative organisms.