Surface bacteriology of venous leg ulcers and healing outcome

Bacteria can be cultured from all venous leg ulcers (VLUs) regardless of healing status, and the significance of a positive swab result in non-clinically infected ulcers is unknown. The aim of this study was to characterise the bacteriological flora of VLUs by routine culture to determine whether the data generated had prognostic value.

The ulcers of 178 patients were sampled weekly for 12 weeks and healing outcome monitored while the limb was treated with graduated compression. Wound bacteriology was assessed using culture methodology standardised to ensure data reproducibility.

153 individual bacterial species were identified. The species most frequently found were Staphylococcus aureus (64.3% of assessments), Corynebacterium striatum (60.6%), Pseudomonas aeruginosa (32.6%), Helcococcus kunzii (22.0%), Finegoldia magna (21.4%) and Proteus mirabilis (16.1%). No single species or the presence of anaerobes and increasing diversity of bacterial species, previously thought to be predictive of impaired healing, was shown to be associated with healing outcome. The presence of C striatum was associated with healing outcome but not after adjusting for the known prognostic factors of wound area and duration.

Routine bacteriological culture analysis of the VLU wound surface may be used to identify diverse flora in all ulcers. However, the data generated are of no additional value as a prognostic indicator of healing outcome. The presence of C striatum may represent colonisation of non-healing VLU by normal skin flora.