Background The role of bacteria in the pathogenesis of chronic venous leg ulcers (CVLU) is unclear. The objective of the study was to establish the aerobic and anaerobic bacteriology of CVLU.

Methods A retrospective review was carried out of the clinical and microbiological laboratory records obtained from patients with CVLU. Microorganisms were grown from 43 specimens obtained from 41 patients.

Results Aerobic or facultative bacteria alone were present in 18 (42%) specimens, anaerobic bacteria only in three (7%), and mixed aerobic–anaerobic flora in 22 (51%).

In total, there were 97 isolates, 64 aerobic or facultative and 33 anaerobic, an average of 2.3 isolates per specimen (1.5 aerobes and 0.8 anaerobes). The predominant aerobic organisms were Staphylococcus aureus (26 isolates), group D streptococci (5), and Escherichia coli (5). The predominant anaerobes were Peptostreptococcus spp. (15), Bacteroides fragilis group (6), Propionibacterium acnes (4), and Prevotella spp. (3).

Conclusions CVLU have a polymicrobial aerobic–anaerobic flora.