A prospective study of the microbiology of chronic venous leg ulcers to reevaluate the clinical predictive value of tissue biopsies and swabs

Abstract

This study determined whether comprehensive microbiological analysis offered real predictive value in terms of healing outcome, and assessed the clinical usefulness of surface swabs vs. tissue biopsies for clinically noninfected leg wounds. The wound microflora of 70 patients with chronic venous leg ulcers was quantified after sampling by swabbing and biopsy. A highly significant association between wound surface area at 4 weeks and eventual healing at 6 months was found (p<0.001), although initial wound size, sex, height, and weight were not significant predictors of outcome (p>0.1). A significant association between healing and bacterial diversity in the wound as assessed by swab (p=0.023) was demonstrated. Furthermore, the bacterial density of wound surface area by swab (CFU/mL; p=0.018) or biopsy (CFU/g tissue; p=0.038) were shown to be independent predictors of nonhealing. Logistic regression showed that microbiological analysis of biopsies provided no additional prognostic information when compared with analysis of the surface microflora (p=0.27). Hence, if biopsies do not contribute significantly to patient management, their use should be discouraged in clinically noninfected wounds. Furthermore, independent predictors of healing, such as wound surface microbial diversity and density, could identify patients likely to have an unfavorable outcome and to whom resources should be targeted.

Prevalence of resistance phenotypes in Staphylococcus aureus and coagulase-negative isolates of venous ulcers of primary healthcare patients

“…There is a strong association between the occurrence of a chronic wound and the duration of the empirical antimicrobial therapy 7 . Infection treatment failures within the community have been associated with complication of the infection, as well as the increase in the consumption of antimicrobials in primary healthcare 40 .…”

“…The correct treatment for venous ulcers includes the microbiological testing to identify pathogens [38][39][40] . A careful indication of antimicrobials should be associated to other therapies that, together, could improve the healing process 23 .…”

Frotis superficial frente a aspiración percutánea para el diagnóstico de infección de herida crónica: ¿resultados discrepantes?

“…Por un lado, los estudios que destacan que los aspirados subestiman las bacterias aisladas 9,12,[18][19][20] , los que opinan que la torunda mayoritariamente refleja colonización 9,21,22 , y los que preconizan que la torunda cuantitativa/semicuantitativa es una alternativa razonable en determinadas ocasiones a la biopsia (patrón de referencia) 16,17,[23][24][25][26][27] . Desde el punto de vista microbiológico, pensamos que hay tres aspectos que considerar.…”

“…El primer aspecto, es que partimos de la base de que todas las heridas crónicas con un tiempo prolongado de evolución están colonizadas 26,28 , por lo que la toma de muestras nunca debe hacerse en ausencia de signos y síntomas clínicos de infección que lo justifiquen. El diagnóstico de infección de herida crónica sigue siendo fundamentalmente clínico y el diagnóstico microbiológico debe reservarse para los casos en los que se precisa conocer la etiología de la infección 5 .…”

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.…”