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A quantitative swab is a good non-invasive alternative to a quantitative biopsy for quantifying bacterial load in wounds healing by second intention in horses
- Van Hecke, L.L., Hermans, K., Haspeslagh, M., Chiers, K., Pint, E., Boyen, F., Martens, A.M.
- The veterinary journal 2017 v.225 pp. 63-68
- bacteria, bacteriology, biofilm, biopsy, cell biology, granulation tissue, horses, leukocyte count, microbial load, reference standards
- The aim of this study was to evaluate different techniques for diagnosing wound infection in wounds healing by second intention in horses and to assess the effect of a vortex and sonication protocol on quantitative bacteriology in specimens with a histologically confirmed biofilm. In 50 wounds healing by second intention, a clinical assessment, a quantitative swab, a semi-quantitative swab, and a swab for cytology were compared to a quantitative tissue biopsy (reference standard). Part of the biopsy specimen was examined histologically for evidence of a biofilm.There was a significant, high correlation (P<0.001; r=0.747) between the outcome of the quantitative swabs and the quantitative biopsies. The semi-quantitative swabs showed a significant, moderate correlation with the quantitative biopsies (P<0.001; ρ=0.524). Higher white blood cell counts for cytology were significantly associated with lower log10 colony-forming units (CFU) in the wounds (P=0.02). Wounds with black granulation tissue showed significantly higher log10 CFU (P=0.003). Specimens with biofilms did not yield higher bacteriological counts after a vortex and sonication protocol was performed to release bacteria from the biofilm. Based on these findings, a quantitative swab is an acceptable non-invasive alternative to a quantitative biopsy for quantifying bacterial load in equine wounds healing by second intention.