Irrigation-aspiration for culturing draining decubitus ulcers: correlation of bacteriological findings with a clinical inflammatory scoring index

Abstract

Biopsy of infected decubitus ulcers for culture disrupts tissues and may disseminate infection. Antimicrobial prophylaxis to prevent dissemination of infection may adversely affect biopsy culture results. Irrigation-aspiration to obtain submarginal specimens from draining decubitus ulcers was studied as an atraumatic, noninvasive culturing technique to serve as an alternative to biopsy in research activities. Two aspirates were obtained serially from 32 subjects; in 12 subjects, biopsies were also performed immediately. A median of 4.5 bacterial species was recovered per ulcer by irrigation-aspiration. Recent antimicrobial treatment had no evident effect on the recovery of bacterial species in general or, specifically, on the recovery of Bacteroides species. Concordance of results for both aspirates was 97.6% for aerobes and 91.8% for anaerobes, indicating no interactive methodological effect of the first irrigation-aspiration on the second. Compared with biopsy isolates for one aspirate, the sensitivity was 93% and the specificity was 99.0%; for another aspirate, the sensitivity was 94.7% and the specificity was 99.5%. The positive predictive value for either aspirate was greater than or equal to 93.9%. A weighted clinical index to score inflammatory ulcer characteristics was devised (score range, 0 to 15). In the absence of anaerobes in 15 subjects, the mean score was 6.1 +/- 3.5; in the presence of anaerobes in 17 subjects, the mean score was 9.4 +/- 3.2 (P = 0.008). The presence of aerobic gram-positive or gram-negative species did not significantly affect scores. Irrigation-aspiration for culture and clinical scoring of inflammation should permit independent serial measures of bacteriological and clinical courses of draining decubitus ulcers without patient risk or discomfort.