Amanda W. Ernlund PhD1 | Lauren T. Moffatt PhD2,3 | Collin M. Timm PhD1 | Kristina K. Zudock BS1 | Craig W. Howser MS1 | Kianna M. Blount BS1 | Abdulnaser Alkhalil PhD2 | Jeffrey W. Shupp MD, FACS2,3 | David K. Karig PhD1,4

1 Department of Research and Exploratory Development, Johns Hopkins Applied Physics Laboratory, Laurel, Maryland

2 The Firefighters' Burn and Surgical Research Laboratory, MedStar Health Research Institute, Hyattsville, Maryland

3 Departments of Surgery, Biochemistry and Molecular & Cellular Biology, Georgetown University School of Medicine, Washington, District of Columbia

4 Department of Bioengineering, Clemson University, 301 Rhodes Research Center, Clemson, South Carolina Correspondence David K. Karig, Department of Bioengineering, Clemson University, 301 Rhodes Research Center, Clemson, SC. Email: 该Email地址已收到反垃圾邮件插件保护。要显示它您需要在浏览器中启用JavaScript。 Funding information Army Research Office, Grant/Award Number: W911NF-14-1-0490; Army Research Laboratory

Abstract

Common treatment for venous leg wounds includes topical wound dressings with compression. At each dressing change, wounds are debrided and washed; however, the effect of the washing procedure on the wound microbiome has not been studied. We hypothesized that wound washing may alter the wound microbiome. To characterize microbiome changes with respect to wound washing, swabs from 11 patients with chronic wounds were sampled before and after washing, and patient microbiomes were characterized using 16S rRNA sequencing and culturing. Microbiomes across patient samples prior to washing were typically polymicrobial but varied in the number and type of bacterial genera present. Proteus and Pseudomonas were the dominant genera in the study. We found that washing does not consistently change microbiome diversity but does cause consistent changes in microbiome composition. Specifically, washing caused a decrease in the relative abundance of the most highly represented genera in each patient cluster. The finding that venous leg ulcer wound washing, a standard of care therapy, can induce changes in the wound microbiome is novel and could be potentially informative for future guided therapy strategies.

KEYWORDS

16S sequencing, microbiome, venous stasis ulcers, wound treatment.

Matthew Malone1,2,3 | Michael Radzieta1,3 | Saskia Schwarzer1,2 | Slade O. Jensen1,3,4 | Lawrence A. Lavery5

1 South West Sydney Limb Preservation and Wound Research, South West Sydney Local Health District, Sydney, Australia

2 High Risk Foot Service, Liverpool Hospital, South West Sydney LHD, Sydney, Australia

3 Infectious Diseases and Microbiology, School of Medicine, Western Sydney University, Sydney, Australia

4 Antimicrobial Resistance and Mobile Elements Group, Ingham Institute of Applied Medical Research, Sydney, Australia

5 Department of Plastic Surgery, University of Texas Southwestern Medical Center, Dallas, Texas

Abstract

       This proof-of-concept study sought to determine the effects of standard of care (SOC) and a topically applied concentrated surfactant gel (SG) on the total microbial load, community composition, and community diversity in nonhealing diabetic foot ulcers (DFUs) with chronic biofilm infections. SOC was provided in addition to a topical concentrated SG, applied every 2 days for 6 weeks. Wound swabs were obtained from the base of ulcers at baseline (week 0), week 1, mid-point (week 3), and end of treatment (week 6). DNA sequencing and real-time quantitative polymerase chain reaction (qPCR) were employed to determine the total microbial load, community composition, and diversity of patient samples. Tissue specimens were obtained at baseline and scanning electron microscopy and peptide nucleic acid fluorescent in situ hybridisation with confocal laser scanning microscopy were used to confirm the presence of biofilm in all 10 DFUs with suspected chronic biofilm infections. The application of SG resulted in 7 of 10 samples achieving a reduction in mean log10 total microbial load from baseline to end of treatment (0.8 Log10 16S copies, ±0.6), and 3 of 10 samples demonstrated an increase in mean Log10 total microbial load (0.6 log10 16S copies, ±0.8) from baseline to end of treatment. Composition changes in microbial communities were driven by changes to the most dominant bacteria. Corynebacterium sp. and Streptococcus sp. frequently reduced in relative abundance in patient samples from week 0 to week 6 but did not disappear. In contrast, Staphylococcus sp., Finegoldia sp., and Fusobacterium sp., relative abundances frequently increased in patient samples from week 0 to week 6. The application of a concentrated SG resulted in varying shifts to diversity (increase or decrease) between week 0 and week 6 samples at the individual patient level. Any shifts in community diversity were independent to changes in the total microbial loads. SOC and a topical concentrated SG directly affect the microbial loads and community composition of DFUs with chronic biofilm infections.

KEYWORDS

diabetic foot ulcer, biofilm, Poloxomer-188, concentrated surfactant gel.

Key messages

• standard of care (SOC) and the use of a topical concentrated surfactant gel (SG) reduced the total microbial load of diabetic foot ulcers with chronic biofilm infections on average by 0.8 Log10 (range = 0–1.6 Log10)

• SOC in addition to the use of a topical concentrated SG caused reductions in the most abun dant sub-operational taxonomic units: Corynebacterium sp. and Streptococcus sp.

• Staphylococcus sp. was not affected by treatment and typically increased in its relative abundance post-treatment

• SOC and a topical concentrated SG caused shifts in microbial community diversity