The microbial flora in venous leg ulcers without clinical signs of infection. Repeated culture using a validated standardised microbiological technique.

Abstract

The change of ulcer size in relation to the presence of species and quantities of microorganisms was analysed in 58 patients with venous leg ulcers, all without clinical signs of infection. Microbiological samples were taken on the day of inclusion and then repeated 4 times at monthly intervals or until the ulcer had healed or was too small to be cultured from. There was growth of microorganisms in all ulcers, and the numbers were below 10(4) per mm2 of ulcer surface in all cases. No correlation was found between ulcer size change and the species and amounts of microorganisms. Sixty-nine species were isolated. Staphylococcus aureus was found in 88%, Enterococcus faecalis in 74%, Enterobacter cloacae and Peptococcus magnus in 29%, and fungi in 11% of the samples. One or more obligate anaerobe species was found in 41% of the samples and in half of the ulcers and constituted 62% of all bacterial species. The colonising ulcer flora was markedly constant over time in the individual ulcers regardless of change in size. Resident bacterial species were found in 57 of the 58 ulcers. If all samples were considered, the microorganisms were associated with not more than one fifth of the variability in healing rate, as shown by linear multiple regression analysis. The same species of microorganisms were found in ulcers that decreased (or healed) and in those that increased in size. Although an association between the microorganisms and ulcer healing could not be ruled out in this study, there seems to be no indication for routinely performed culture in the absence of clinical signs of infection in venous leg ulcers.