Microbiological profile of chronic ulcers of the lower limb: a prospective observational cohort study

The aim of the study was to determine the microbiological profile of chronic lower-limb ulcers in a tertiary outpatient setting.

A prospective observational cohort study of 39 patients with lower-limb ulcers of more than 1 month duration, presenting to the leg ulcer clinic. Superficial swab and punch biopsy samples were taken from each ulcer.

Mean age was 68.7 years. Venous ulcers were most common (51%) followed by arterial ulcers (13%), ulcers in people with diabetes having arterial disease (13%), unspecified ulcers (13%) and ulcers in people with diabetes (10%). The most common organisms were Staphylococcus aureus (38-44%) followed by Pseudomonas aeruginosa (26-28%). Biopsy and swab results were concordant in 18 (46%), had at least one organism in common in 10 (26%) and had no concordance in 11 (28%). Histological analysis did not show any cases of malignancy. Ulcer area was significantly lower after 2 months of treatment (P = 0.047). Venous ulcers had the best outcome at 2 months, whereas people with diabetes with arterial disease fared poorly.

The microbiological profile of chronic leg ulcers has application to general treatment principles as well in guiding the necessity and choice of antibiotic therapy. Concordance between swab and biopsy results was poor; we recommend biopsy in the tertiary setting.