LETTER TO THE EDITOR

Highlights from the Montana wound biofilm retreat

To the Editor:

Over the past several years, an increasing number of re-

ports have investigated the potential role of biofilms in the

delayed healing of chronic wounds. The Center for Biofilm

Engineering (CBE) at Montana State University received a

P20 Exploratory Research Center Grant from the National

Institute of General Medical Science to investigate biofilms

in chronic wounds. As part of our outreach program for

this exploratory center, we held a Wound Biofilm Retreat

in Bozeman, MT. This Retreat brought together scientists,

clinicians, and company representatives to present the latest

research on how microbial biofilms impact wound healing.

Attendees included representatives from 25 companies and

12 universities with such diverse backgrounds as clinical

practice, microbiology, and immunology.

To kick-off the retreat, Philip Stewart, Director of the

CBE, gave a brief history of the biofilm hypothesis in chronic

wound healing and illustrated how the recent spike in publi-

cations underscores increasing interest in the biofilm hypoth-

esis within the wound healing community. Invited speakers

included Thomas Bjarnsholt, from the University of Copen-

hagen, Denmark, who presented some of his recent work us-

ing in situ hybridization (peptide nucleic acid probes-

fluorescence in situ hybridization) in clinical specimens to

evaluate the ecology of biofilms in chronic wounds. Repre-

senting the clinical importance of biofilms in chronic wounds,

Gerald Lazarus and Jonathan Zenilman of the Johns Hop-

kins Wound Center in Baltimore, Maryland, presented recent

clinical work from their laboratories that demonstrated the

need for a rapid, clinically relevant tool for identification and

characterization of bacteria in chronic wounds. Importantly,

Drs. Lazarus and Zenilman demonstrated that commonly

used qualitative assays to assess microbial burden do not cor-

relate well with quantitative assays, indicating a need for new

analytic methods for chronic wounds.

Relevant chronic wound models are needed, and high-

lighted at the Retreat were multiple models using various or-

ganisms. Stephen Davis, from the Miller School of Medicine,

University of Miami, highlighted his research with a porcine

wound model in which he demonstrated that established bac-

terial biofilms in wounds slowed the response time for topical

antimicrobial activity. Thomas Mustoe, Chief of Plastic Sur-

gery at Northwestern Memorial Hospital in Chicago, pre-

sented work in which his group demonstrated delayed

reepithelialization caused by the presence of bacterial biofilm

in a murine cutaneous wound model. Dr. Mustoe also pre-

sented a rabbit ear dermal ulcer model his group is developing

to study chronic wounds. Gregory Schultz, from the Institute

for Wound Research at University of Florida in Gainesville,

presented work from his group on the development and dem-

onstration of an in vitro pigskin model. Testing this model

with antimicrobial dressings, Dr. Schultz’s group found that

multiple antibiotics and antimicrobials, such as silver, were

ineffective in killing mature bacterial biofilms; however, this

model did identify cadexomer iodine as an effective antibio-

film treatment. Finally, Ge Alice Zhao from the University of

Washington School of Medicine presented on a murine

chronic wound model they are using to assess how bacterial

biofilm affects wound healing in vivo.

In vitro wound modeling has the advantages of simplicity

and environmental control. Mary Cloud Ammons of the CBE

presented her recent work demonstrating the use of antimi-

crobial treatments that act synergistically against an estab-

lished biofilm. Understanding host–pathogen interactions in

the biofilm contaminated wound will improve our under-

standing of how chronicity develops. To this end, Kelly Kirk-

er of the CBE presented an in vitro scratch model she has

developed. In this model, Dr. Kirker demonstrated that the

presence of biofilm could inhibit scratch closure and that an-

tibiotic treatment of the biofilm improved the migration of

keratinocytes.

As molecular techniques evolve, their utility in the field of

wound care contributes to a greater depth of understanding of

the processes of wound healing and chronicity in the presence

or absence of bacterial biofilm. Taking a novel research ap-

proach, Chandan Sen, the Director of the Ohio State Univer-

sity Comprehensive Wound Center in Columbus, Ohio,

presented work from his group that utilized a knockdown

model in human endothelial cells (EC), which targeted the

microRNA machinery. Using this model, Dr. Sen demon-

strated the importance of microRNA in regulating redox sig-

naling and thus the angiogenic properties of EC. Oxidative

stress also influences the physiology of the biofilm as was

demonstrated by Haluk Beyenal of Washington State Uni-

versity. Using an in vitro model developed by the CBE, Dr.

Beyenal found that biofilms harbored anoxic niches for each

of the wound isolates tested. Finally, Pat Secor of the CBE

utilized molecular and microscopic methods to examine host/

pathogen interactions in vitro. Using a transwell model, he

demonstrated that bacterial biofilm induced cytoskeletal dis-

ruption in both human keratinocyte and human fibroblast cell

cultures. These data have significant implications for the

wound healing process in the presence of bacterial biofilms.

To conclude the daylong Retreat, the CBE moderated a

roundtable discussion that included all academic and indus-

trial participants. From this roundtable discussion emerged a

clear consensus on where the field of biofilm research in

wound care needs to proceed. First, the clinical participants

emphasized the need for clinically relevant diagnostic tools

for identifying and characterizing bacterial biofilm in the

wound. From the academic participants emerged a clear in-

terest in understanding the microbial ecology associated with

Wound Rep Reg (2009) 17 626–627 c� 2009 by the Wound Healing Society626

Wound Repair and Regeneration



wounds and a need for more intensive molecular analysis of

the interface between the host and the pathogen in biofilm in-

fected wounds. Finally, the industrial participants expressed a

need for greater clarity on regulatory policies with regard to

wound treatments. All in all, the Wound Biofilm Retreat suc-

cessfully demonstrated how the field of biofilm research and

the field of wound care have interwoven to create a new,

emerging field of critical medical importance. There remain a

great many questions to be answered, but at the conclusion of

the Retreat the importance of biofilm research in wound heal-

ing was clear.

Mary Cloud B. Ammons;
Garth A. James;
Philip S. Stewart

Center for Biofilm Engineering, Montana State University,
Montana, USA

Wound Rep Reg (2009) 17 626–627 c� 2009 by the Wound Healing Society 627

Letter to the Editor