Diagnostic validity of three swab techniques for identifying chronic wound infection

Abstract

This study examined the diagnostic validity of three different swab techniques in identifying chronic wound infection. Concurrent swab specimens of chronic wounds were obtained using wound exudate, the Z-technique, and the Levine technique, along with a specimen of viable wound tissue. Swab and tissue specimens were cultured using quantitative and qualitative laboratory procedures. Infected wounds were defined as those containing 1 x 10(6) or more organisms per gram of tissue. Accuracy was determined by associating the quantitative cultures of swab specimens with the cultures from tissue specimens using receiver operating characteristic curves. Of the 83 study wounds, 30 (36%) were infected. Accuracy was the highest for swab specimens obtained using Levine's technique at 0.80. Based on Levine's technique, a critical threshold of 37,000 organisms per swab provided a sensitivity of 90% and a specificity of 57%. The mean concordance between swab specimens obtained using Levine's technique and tissue specimens was 78%. The findings suggest that swab specimens collected using Levine's technique provide a reasonably accurate measure of wound bioburden, given that they are more widely applicable than tissue cultures. The diagnostic validity of Levine's technique needs further study using an alternative reference standard, such as the development of infection-related complications.

Bacterial Load Predicts Healing Rate in Neuropathic Diabetic Foot Ulcers

“…Our method of ulcer fluid sampling, from the reproducible CFU counts from the same wound, and others (13) have also shown that postdebridement wound fluid CFU highly correlates with CFU counts derived from tissue samples in the same wound.…”

Wound healing potential of the ethanolic extracts of Bidens pilosa and Ocimum suave

“…The essential oils of four Ocimum species grown in Rwanda have been shown to possess antimicrobial activity against Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Trichophyton metagrophytes (Janssen et al, 1989). It is probable that the antimicrobial activity of the oils from O. suave may be helpful in keeping away microor-ganisms especially S. aureus which is a major bacterial burden in chronic wounds (Gardner et al, 2004) and therefore enhance wound healing. The plant extracts left no prominent scar at the wound sites while neomyicin sulfate treated groups had prominent scars.…”

Association Between Microbial Bioburden and Healing Outcomes in Venous Leg Ulcers: A Review of the Evidence

“…23,24 Most studies of quantitative bacterial cultures in chronic wounds have not associated microbial load with healing outcomes. [25][26][27] Two exceptions include Davies et al 23 and Lantis et al 24 Davies et al prospectively performed quantitative tissue biopsies and surface swabs of 66 patients with clinically noninfected chronic VLUs at baseline and monitored healing outcomes. They showed that neither quantitative tissue biopsy (CFU/g) nor surface swabs (CFU/mL) of the wound at baseline predicted healing at 6 months in a logistic regression model.…”

“…Overall, cultivation methods have been shown to be comparable between biopsies and swabs for aerobes, although there are more discrepancies for anaerobes and overall quantities of bacteria, suggesting uneven vertical distribution of at least some species as discussed in the Intra-and Interwound Variation section. 23,25,37,40 Molecular-based studies performed to date have predominantly used sharp debridement samples without comparison of different sampling methods or indication of the depth of the wound sampled.…”