Bacterial isolates from necrotizing fasciitis: a clinico-pathological perspective.

BACKGROUND: Necrotizing fasciitis (NF) is a progressive, polymicrobial, potentially fatal soft tissue infection that can affect both sexes, all age groups and any anatomical region of the body. Identification of the offending microorganisms is important, since the eventual outcome of treatment is dependent on aggressive surgical, chemotherapeutic and supportive therapy. AIM: To determine the spectrum of aerobic bacterial organisms responsible for NF in Sokoto, Northwestern Nigeria, and to establish a baseline for which further studies can be conducted. PATIENTS AND METHODS: A 5-year prospective study of aerobic bacteria isolated from all consecutive patients with NF seen at the Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria from January 2001 to December 2005. All necessary information from each patient was fed into the computer for analysis.
RESULTS: There were 62 patients, of which 33 (53.2%) were males while the remaining 29 (46.8%) were females. The ages ranged from six days to 70 years (mean = 21.4 years). One or more precipitating factors were identified in 32 (51.6%) patients, while 40 (64.5%) patients had identifiable pre-morbid pathology. The body surface area (BSA) involved ranged from 1 31% (mean = 5.2%). The commonest anatomical region involved was the trunk in 23 (37.1%) patients; this was followed by the lower limbs, upper limbs, head and neck, perineum and buttocks in that order. From the 62 patients, 176 aerobic cultures were carried out. Of this, 147 cultures (83.5%) were positive, while the remaining 29 (16.5%) grew no organisms after 48 hours of incubation. The commonest offending organisms were Staphylococcus aureus and Pseudomonas aeruginosa. Infection was polymicrobial in 64% of patients. Cephalosporins, quinolones and aminoglycosides were the most sensitive antibiotics. Multiple wound debridements were required in nearly half of the patients. The duration of hospital stay ranged from 3 132 days (mean=39 days). The overall mortality was 14.5%.
CONCLUSION: NF is essentially polymicrobial, deriving significant contributions from both gram-negative and gram-positive bacteria. The cultural characteristics of the disease, and sensitivity to antibiotics, require periodic assessments.