Distinct polymicrobial populations in the chronic foot ulcer. (A) Severe plantar ulcer located in the posterior calcaneal area as seen upon consultation. (B) Magnetic resonance imaging (MRI) of the left lateral side of the right foot. Multilayered microbial analysis of the ulcer was done by culture, PCR, and denaturing high-performance liquid chromatography (DHPLC). Bacteria (S. aureus, P. vulgaris, and F. nucleatum) were identified from the upper level of the ulcer by a superficial biopsy using both, culture and PCR/DHPLC (top). Bacteria (G. morbillorum, P. asaccharolytica, B. fragilis, and A. haemolyticum) were identified from the lower level of the ulcer by PCR and DHPLC analysis only (C).