The quantitative swab culture and smear: A quick, simple method for determining the number of viable aerobic bacteria on open wounds

Abstract

The quantitative swab culture is a reliable method for quantifying the number of viable bacteria colonizing open wounds. For open wounds in burn patients, the swab bacterial count is linearly related to biopsy quantification of viable bacteria in the underlying tissue. This technique is simple and requires no surgical manipulation of the wound. For a wound of uniform appearance, the standard deviation of a single swab culture from the mean log bacterial count for a series of cultures from widely spaced areas on the wound is +/- 0.85 logs; 95% confidence limits are +/- 1.7 logs from the mean. A Gram-stained smear from a wound swab requires less than 10 minutes to prepare. Visualization of bacteria on the smear indicates that 106 or more bacteria per swab are present. The value of the smear and swab techniques for predicting safe wound closure may be inferred from the published reports of others and the direct relationship between the swab and biopsy counts of viable bacteria for open wounds.