Browsing by Author "Wolcott, Randall D."

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Biofilm maturity studies indicate sharp debridement opens a time-dependent therapeutic window
(2010-08) Wolcott, Randall D.; Rumbaugh, Kendra P.; James, Garth A.; Schultz, Gregory; Phillips, P.; Yang, Q.; Watters, C.; Stewart, Philip S.; Dowd, Scot E.
Objective: To investigate the hypothesis that newly formed wound biofilms (or bioburdens) are more susceptible to antimicrobial treatment.Method: Four separate and distinct models were performed by four separate biofilm research laboratories to evaluate the resistance of biofilms to antimicrobial treatments over time. These included a drip-flow biofilm model along with a hydrodebridement study, a porcine skin punch biopsy ex vivo model, a mouse chronic wound model and clinical longitudinal debridement study.Results: All four models showed that, within the first 24 hours, the biofilm community was more susceptible to the selected antibiotics, and after maturing for up to 48 hours became increasingly tolerant. In each model, there was at least a 24-hour period in which the biofilms were more resistant to antibiotics. Each of the models utilised showed a significant decrease in the resistance of the biofilm/ burden to gentamicin for up to 24 hours with a confidence interval of at least 95%. The resistance increased in each of the models by 48 hours and reached original resistance levels by 72 hours.Conclusion: These data suggest the principles of biofilm-based wound care, along with the use of serial debridement to continually remove mature biofilm, followed by biofilm wound management strategies, including topical antibiotics while the bioburden is still immature and more susceptible, are valid.Conflict of interest: SED is director of Research and Testing Laboratory, a commercial laboratory that develops molecular methods for diagnosis of wounds and infections and CEO of Pathogenius Laboratories, which is a molecular pathogen diagnostic company with a focus on chronic wounds. RDW is medical director of Southwest Regional Wound Care Center and inventor of biofilm-based wound care principles.
Biofilms in chronic wounds
(2008-01) James, Garth A.; Swogger, E.; Wolcott, Randall D.; Pulcini, Elinor D.; Secor, Patrick R.; Sestrich, Jennifer; Costerton, J. William; Stewart, Philip S.
Chronic wounds including diabetic foot ulcers, pressure ulcers, and venous leg ulcers are a worldwide health problem. It has been speculated that bacteria colonizing chronic wounds exist as highly persistent biofilm communities. This research examined chronic and acute wounds for biofilms and characterized microorganisms inhabiting these wounds. Chronic wound specimens were obtained from 77 subjects and acute wound specimens were obtained from 16 subjects. Culture data were collected using standard clinical techniques. Light and scanning electron microscopy techniques were used to analyze 50 of the chronic wound specimens and the 16 acute wound specimens. Molecular analyses were performed on the remaining 27 chronic wound specimens using denaturing gradient gel electrophoresis and sequence analysis. Of the 50 chronic wound specimens evaluated by microscopy, 30 were characterized as containing biofilm (60%), whereas only one of the 16 acute wound specimens was characterized as containing biofilm (6%). This was a statistically significant difference (p<0.001). Molecular analyses of chronic wound specimens revealed diverse polymicrobial communities and the presence of bacteria, including strictly anaerobic bacteria, not revealed by culture. Bacterial biofilm prevalence in specimens from chronic wounds relative to acute wounds observed in this study provides evidence that biofilms may be abundant in chronic wounds.
Consensus guidelines for the identification and treatment of biofilms in chronic nonhealing wounds
(2017-09) Schultz, Gregory; Bjarnsholt, Thomas; James, Garth A.; Leaper, David; McBain, Andrew J.; Malone, Matthew; Stoodley, Paul; Swanson, Terry; Tachi, Masahiro; Wolcott, Randall D.
Background: Despite a growing consensus that biofilms contribute to a delay in the healing of chronic wounds, conflicting evidence pertaining to their identification and management can lead to uncertainty regarding treatment. This, in part, has been driven by reliance on in vitro data or animal models, which may not directly correlate to clinical evidence on the importance of biofilms. Limited data presented in human studies have further contributed to the uncertainty. Guidelines for care of chronic wounds with a focus on biofilms are needed to help aid the identification and management of biofilms, providing a clinical focus to support clinicians in improving patient care through evidence-based medicine. Methods: A Global Wound Biofilm Expert Panel, comprising 10 clinicians and researchers with expertise in laboratory and clinical aspects of biofilms, was identified and convened. A modified Delphi process, based on published scientific data and expert opinion, was used to develop consensus statements that could help identify and treat biofilms as part of the management of chronic nonhealing wounds. Using an electronic survey, panel members rated their agreement with statements about biofilm identification and treatment, and the management of chronic nonhealing wounds. Final consensus statements were agreed on in a face-to-face meeting. Results: Participants reached consensus on 61 statements in the following topic areas: understanding biofilms and the problems they cause clinicians; current diagnostic options; clinical indicators of biofilms; future options for diagnostic tests; treatment strategies; mechanical debridement; topical antiseptics; screening antibiofilm agents; and levels of evidence when choosing antibiofilm treatments. Conclusion: This consensus document attempts to clarify misunderstandings about the role of biofilms in clinical practice, and provides a basis for clinicians to recognize biofilms in chronic nonhealing wounds and manage patients optimally. A new paradigm for wound care, based on a stepped-down treatment approach, was derived from the consensus statements.
In vitro susceptibility of established biofilms composed of a clinical wound isolate of Pseudomonas aeruginosa treated with lactoferrin and xylitol
(2009-03) Ammons, Mary Cloud B.; Ward, L. S.; Fisher, Steve T.; Wolcott, Randall D.; James, Garth A.
The medical impact of bacterial biofilms has increased with the recognition of biofilms as a major contributor to chronic wounds such as diabetic foot ulcers, venous leg ulcers and pressure ulcers. Traditional methods of treatment have proven ineffective, therefore this article presents in vitro evidence to support the use of novel antimicrobials in the treatment of Pseudomonas aeruginosa biofilm. An in vitro biofilm model with a clinical isolate of P. aeruginosa was subjected to treatment with either lactoferrin or xylitol alone or in combination. Combined lactoferrin and xylitol treatment disrupted the structure of the P. aeruginosa biofilm and resulted in a >2log reduction in viability. In situ analysis indicated that while xylitol treatment appeared to disrupt the biofilm structure, lactoferrin treatment resulted in a greater than two-fold increase in the number of permeabilised bacterial cells. The findings presented here indicated that combined treatment with lactoferrin and xylitol significantly decreases the viability of established P. aeruginosa biofilms in vitro and that the antimicrobial mechanism of this treatment includes both biofilm structural disruption and permeablisation of bacterial membranes.
The prevalence of biofilms in chronic wounds: a systematic review and meta-analysis of published data
(2017-01) Malone, Matthew; Bjarnsholt, Thomas; McBain, Andrew J.; James, Garth A.; Stoodley, Paul; Leaper, David; Tachi, Masahiro; Schultz, Gregory; Swanson, Terry; Wolcott, Randall D.
The presence of biofilms in chronic non-healing wounds, has been identified through in vitro model and in vivo animal data. However, human chronic wound studies are under-represented and generally report low sample sizes. For this reason we sought to ascertain the prevalence of biofilms in human chronic wounds by undertaking a systematic review and meta-analysis. Our initial search identified 554 studies from the literature databases (Cochrane Library, Embase, Medline). After removal of duplicates, and those not meeting the requirements of inclusion, nine studies involving 185 chronic wounds met the inclusion criteria. Prevalence of biofilms in chronic wounds was 78.2 % (confidence interval [CI 61.6-89, p<0.002]). The results of our meta-analysis support our clinical assumptions that biofilms are ubiquitous in human chronic non-healing wounds.
Production of cell–cell signaling molecules by bacteria isolated from human chronic wounds
(2010-05) Rickard, A. H.; Colacino, K. R.; Manton, K. M.; Morton, R. I.; Pulcini, Elinor D.; Pfeil, J.; Rhoads, Daniel D.; Wolcott, Randall D.; James, Garth A.
Aim: To (i) identify chronic wound bacteria and to test their ability to produce acyl-homoserine-lactones (AHLs) and autoinducer-2 (AI-2) cellâ€“cell signalling molecules and (ii) determine whether chronic wound debridement samples might contain these molecules. Methods and Results: Partial 16S rRNA gene sequencing revealed the identity of 46 chronic wound strains belonging to nine genera. Using bio-reporter assays, 69-6% of the chronic wound strains were inferred to produce AI-2, while 19-6% were inferred to produce AHL molecules. At least one strain from every genus, except those belonging to the genera Acinetobacter and Pseudomonas, were indicated to produce AI-2. Production of AI-2 in batch cultures was growth-phase dependent. Cross-feeding assays demonstrated that AHLs were produced by Acinetobacter spp., Pseudomonas aeruginosa and Serratia marcescens. Independent from studies of the bacterial species isolated from wounds, AHL and/or AI-2 signalling molecules were detected in 21 of 30 debridement samples of unknown microbial composition. Conclusion: Chronic wound bacteria produce cellâ€“cell signalling molecules. Based on our findings, we hypothesize that resident species generally produce AI-2 molecules, and aggressive transient species associated with chronic wounds typically produce AHLs. Both these classes of cellâ€“cell signals are indicated to be present in human chronic wounds. Significance and Impact of the Study: Interbacterial cellâ€“cell signalling may be an important factor influencing wound development and if this is the case, the presence of AHLs and AI-2 could be used as a predictor of wound severity. Manipulation of cellâ€“cell signalling may provide a novel strategy for improving wound healing.
Survey of bacterial diversity in chronic wounds using pyrosequencing, DGGE, and full ribosome shotgun sequencing
(2008-03) Dowd, Scot E.; Sun, Yan; Secor, Patrick R.; Rhoads, Daniel D.; Wolcott, Benjamin M.; James, Garth A.; Wolcott, Randall D.
BACKGROUND:Chronic wound pathogenic biofilms are host-pathogen environments that colonize and exist as a cohabitation of many bacterial species. These bacterial populations cooperate to promote their own survival and the chronic nature of the infection. Few studies have performed extensive surveys of the bacterial populations that occur within different types of chronic wound biofilms. The use of 3 separate 16S-based molecular amplifications followed by pyrosequencing, shotgun Sanger sequencing, and denaturing gradient gel electrophoresis were utilized to survey the major populations of bacteria that occur in the pathogenic biofilms of three types of chronic wound types: diabetic foot ulcers (D), venous leg ulcers (V), and pressure ulcers (P). RESULTS:There are specific major populations of bacteria that were evident in the biofilms of all chronic wound types, including Staphylococcus, Pseudomonas, Peptoniphilus, Enterobacter, Stenotrophomonas, Finegoldia, and Serratia spp. Each of the wound types reveals marked differences in bacterial populations, such as pressure ulcers in which 62% of the populations were identified as obligate anaerobes. There were also populations of bacteria that were identified but not recognized as wound pathogens, such as Abiotrophia para-adiacens and Rhodopseudomonas spp. Results of molecular analyses were also compared to those obtained using traditional culture-based diagnostics. Only in one wound type did culture methods correctly identify the primary bacterial population indicating the need for improved diagnostic methods.CONCLUSIONS: If clinicians can gain a better understanding of the wound's microbiota, it will give them a greater understanding of the wound's ecology and will allow them to better manage healing of the wound improving the prognosis of patients. This research highlights the necessity to begin evaluating, studying, and treating chronic wound pathogenic biofilms as multi-species entities in order to improve the outcomes of patients. This survey will also foster the pioneering and development of new molecular diagnostic tools, which can be used to identify the community