One step closer to understanding the role of bacteria in diabetic foot ulcers: characterising the microbiome of ulcers

Abstract

BackgroundThe aim of this study was to characterise the microbiome of new and recurrent diabetic foot ulcers using 16S amplicon sequencing (16S AS), allowing the identification of a wider range of bacterial species that may be important in the development of chronicity in these debilitating wounds. Twenty patients not receiving antibiotics for the past three months were selected, with swabs taken from each individual for culture and 16S AS. DNA was isolated using a combination of bead beating and kit extraction. Samples were sequenced on the Illumina Hiseq 2500 platform.ResultsConventional laboratory culture showed positive growth from only 55 % of the patients, whereas 16S AS was positive for 75 % of the patients (41 unique genera, representing 82 different operational taxonomic units (OTU’s). S. aureus was isolated in 72 % of culture-positive samples, whereas the most commonly detected bacteria in all ulcers were Peptoniphilus spp., Anaerococcus spp. and Corynebacterium spp., with the addition of Staphylococcus spp. in new ulcers. The majority of OTU’s residing in both new and recurrent ulcers (over 67 %) were identified as facultative or strict anaerobic Gram-positive organisms. Principal component analysis (PCA) showed no difference in clustering between the two groups (new and recurrent ulcers).ConclusionsThe abundance of anaerobic bacteria has important implications for treatment as it suggests that the microbiome of each ulcer “starts afresh” and that, although diverse, are not distinctly different from one another with respect to new or recurrent ulcers. Therefore, when considering antibiotic therapy the duration of current ulceration may be a more important consideration than a history of healed ulcer.

A systematic literature review of the human skin microbiome as biomarker for dermatological drug development

“…The role of the skin microbiome in UC was explored in 10 different studies, Table 1 37, 38, 39, 40, 41, 42, 43, 44, 45, 46. Current research into UC microbiome, comprises larger, longitudinal studies, compared to those in PV and HS.…”

“…The skin mycobiota of diabetic foot ulcers was longitudinally assessed and was observed to be highly heterogeneous over time and between subjects while the diversity increased upon antibiotic treatment 45. There have been similar efforts to reveal correlations between patient metadata, treatment and/or clinical outcomes and the cutaneous microbiome in studies investigating the microbiota in UC 38, 42, 43, 44, 46. Overall, the most common found genus in these studies was Staphylococcus , with Staphylococcus aureus the most common species.…”

Diabetic foot infection: Antibiotic therapy and good practice recommendations

“…These studies not only identify a much more diverse bacterial flora within the ulcer, but appear to be able to distinguish actively pathogenic organisms, from non‐pathogenic or colonising organisms with pathogenic potential and have greater sensitivity in detecting pathogenic species in deep tissue samples. The presence of ‘colonising’ bacteria (with pathogenic potential) may be a predictor of relapsing foot infection or chronic persistent ulceration . The presence of additional‐site methicillin‐resistant S. aureus carriage (eg, nasal/perineal) may also predispose to re‐infection .…”

Metataxonomic approach to decipher the polymicrobial burden in diabetic foot ulcer and its biofilm mode of infection

“…A few groups have studied the anaerobic infection of diabetic ulcer, and anaerobes have been found to play a major role in delayed wound healing . Smith et al have studied the new and recurring types of ulcer, and anaerobes were detected in nearly 87% of the samples. Finegoldia , Parvimonas , Peptostreptococcus , veillonella , Anaerococcus , Porphyromonas , Peptoniphilus, and Prevotella were the predominant anaerobic genera identified in the present study.…”