Quantitative microbiology of pressure sores in different stages of healing

The quantitative microbiology of 25 pressure sores in different stages of healing was examined in 25 patients with spinal cord injury. When grossly necrotic tissue was present (stage 1), 5.8 isolates per patient with a density of 6.4 log 10/g was recovered, with comparable findings for aerobes and anaerobes. In the absence of necrotic tissue but with the presence of undermining (stage 2), 1.5 aerobic and 0.2 anaerobic isolates were recovered per patient with a mean density of 2.7 and 0.1 log 10/g of tissue for aerobic and anaerobic isolates, respectively. The lesions were almost sterile in patients with no necrotic tissue and no undermining (stage 3). Foul smell was always associated with the presence of anaerobes in deep tissue cultures, however, six patients with nonfoul-smelling lesions yielded anaerobes. A 75% quantiative concordance was seen between swab and biopsy culture results. The quantitative concordance between peripheral and central biopsy culture results was 63%, showing variability in results from different sampling areas. No relationship was observed between the density of microorganisms and the eventual outcome of the myocutaneous flap procedure.