Matthew Malone

Deep wound cultures correlate well with bone biopsy culture in diabetic foot osteomyelitis

Osteomyelitis is a major complication in patients with diabetic foot ulceration. Accurate pathogenic identification of organisms can aid the clinician to a specific antibiotic therapy thereby preventing the need for amputation.

The prevalence of biofilms in chronic wounds: a systematic review and meta-analysis of published data

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.

Approaches to biofilm-associated infections: the need for standardized and relevant biofilm methods for clinical applications

ABSTRACT Introduction: The concept of biofilms in human health and disease is now widely accepted as cause of chronic infection. Typically, biofilms show remarkable tolerance to many forms of treatments and the host immune response. This has led to vast increase in research to identify new (and sometimes old) anti-biofilm strategies that demonstrate effectiveness against these tolerant phenotypes. Areas covered: Unfortunately, a standardized methodological approach of biofilm models has not been adopted leading to a large disparity between testing conditions. This has made it almost impossible to compare data across multiple laboratories, leaving large gaps in the evidence. Furthermore, many biofilm models testing anti-biofilm strategies aimed at the medical arena have not considered the matter of relevance to an intended application. This may explain why some in vitro models based on methodological designs that do not consider relevance to an intended application fail when applied in vivo at the clinical level. Expert commentary: This review will explore the issues that need to be considered in developing performance standards for anti-biofilm therapeutics and provide a rationale for the need to standardize models/methods that are clinically relevant. We also provide some rational as to why no standards currently exist.

Can molecular DNA-based techniques unravel the truth about diabetic foot infections?

Diabetes foot infections are a common condition and a major causal pathway to lower extremity amputation. Identification of causative pathogens is vital in directing antimicrobial therapy. Historically, clinicians have relied upon culture‐dependent techniques that are now acknowledged as both being selective for microorganisms that thrive under the physiological and nutritional constraints of the microbiology laboratory and that grossly underestimate the microbial diversity of a sample. The amplification and sequence analysis of the 16S rRNA gene has revealed a diversity of microorganisms in diabetes foot infections, extending the view of the diabetic foot microbiome. The interpretation of these findings and their relevance to clinical care remains largely unexplored. The advent of molecular methods that are culture‐independent and employ massively parallel DNA sequencing technology represents a potential ‘game changer’. Metagenomics and its shotgun approach to surveying all DNA within a sample (whole genome sequencing) affords the possibility to characterize not only the microbial diversity within a diabetes foot infection (i.e. ‘which microorganisms are present’) but the biological functions of the community such as virulence and pathogenicity (i.e. ‘what are the microorganisms capable of doing’), moving the focus from single species as pathogens to groups of species. This review will examine the new molecular techniques for exploration of the microbiome of infected and uninfected diabetic foot ulcers, exploring the potential of these new technologies and postulating how they could translate to improved clinical care. Copyright

Effect of cadexomer iodine on the microbial load and diversity of chronic non-healing diabetic foot ulcers complicated by biofilm in vivo

Abstract Objectives: The performance of cadexomer iodine was determined against microbial populations from chronic non-healing diabetic foot ulcers (DFUs) complicated by biofilm in vivo, using molecular, microscopy and zymography methods. Methods: Chronic non-healing DFUs due to suspected biofilm involvement were eligible for enrolment. DNA sequencing and real-time quantitative PCR was used to determine the microbial load and diversity of tissue punch biopsies obtained pre- and post-treatment. Scanning electron microscopy and/or fluorescence in situ hybridization confirmed the presence or absence of biofilm. Zymography was used to determine levels of wound proteases. Results: Seventeen participants were recruited over a 6 month period. Scanning electron microscopy and or fluorescence in situ hybridization confirmed the presence of biofilm in all samples. Eleven participants exhibited log10 reductions in microbial load after treatment (range 1–2 log10) in comparison with six patients who experienced <1 log10 reduction (P = 0.04). Samples were tested for levels of wound proteases pre- and post-treatment. Reductions in the microbial load correlated to reductions in wound proteases pre- and post-treatment (P = 0.03). Conclusions: To the best of our knowledge, this study represents the first in vivo evidence, employing a range of molecular and microscopy techniques, of the ability of cadexomer iodine to reduce the microbial load of chronic non-healing DFUs complicated by biofilm. Further analyses correlating log reductions to optimal duration of therapy and improvements in clinical parameters of wound healing in a larger cohort are required.

A Chronic, Destructive Mycetoma Infection in a Diabetic Foot in Saudi Arabia

This case study describes the presentation of a tropical foot infection that presented in a 38-year-old male farm worker from the eastern province of Saudi Arabia who contracted the fungal infection that is Madurella mycetomatis. Mycetomas or Madura foot is characterized by a slow progressive infection that can result in severe soft tissue and muscle involvement along with destruction of the underlying bone. This foot pathology is rare in the United States and across Europe; however, the increasing influx of a migrant population means that a heightened awareness of its existence is needed.

Microscopy visualisation confirms multi-species biofilms are ubiquitous in diabetic foot ulcers

Increasing evidence within the literature has identified the presence of biofilms in chronic wounds and proposed that they contribute to delayed wound healing. This research aimed to investigate the presence of biofilm in diabetic foot ulcers (DFUs) using microscopy and molecular approaches and define if these are predominantly mono‐ or multi‐species. Secondary objectives were to correlate wound observations against microscopy results in ascertaining if clinical cues are useful in detecting wound biofilm. DFU tissue specimens were obtained from 65 subjects. Scanning electron microscopy (SEM) and peptide nucleic acid fluorescent in situ hybridisation (PNA‐FISH) techniques with confocal laser scanning microscopy (CLSM) were used to visualise biofilm structures. Next‐generation DNA sequencing was performed to explore the microbial diversity. Clinical cues that included the presence of slough, excessive exudate, a gel material on the wound bed that reforms quickly following debridement, poor granulation and pyocyanin were correlated to microscopy results. Of the 65 DFU specimens evaluated by microscopy, all were characterised as containing biofilm (100%, P < 0·001). The presence of both mono‐species and multi‐species biofilms within the same tissue sections were detected, even when DNA sequencing analysis of DFU specimens revealed diverse polymicrobial communities. No clinical correlations were identified to aid clinicians in identifying wound biofilm. Microscopy visualisation, when combined with molecular approaches, confirms biofilms are ubiquitous in DFUs and form either mono‐ or multi‐species biofilms. Clinical cues to aid clinicians in detecting wound biofilm are not accurate for use in DFUs. A paradigm shift of managing DFUs needs to consider anti‐biofilm strategies.

Next generation DNA sequencing of tissues from infected diabetic foot ulcers

We used next generation DNA sequencing to profile the microbiome of infected Diabetic Foot Ulcers (DFUs). The microbiota was correlated to clinical parameters and treatment outcomes to determine if directed antimicrobial therapy based on conventional microbiological cultures are relevant based on genomic analysis. Patients ≥ 18 years presenting with a new Diabetic Foot Infection (DFI) who had not received topical or oral antimicrobials in the two weeks prior to presentation, were eligible for enrolment. Tissue punch biopsies were obtained from infected DFUs for analysis. Demographics, clinical and laboratory data were collected and correlated against microbiota data. Thirty-nine patients with infected DFUs were recruited over twelve-months. Shorter duration DFUs (< six weeks) all had one dominant bacterial species (n = 5 of 5, 100%, p < 0.001), Staphylococcus aureus in three cases and Streptococcus agalactiae in two. Longer duration DFUs (≥ six weeks) were diversely polymicrobial (p < 0.01) with an average of 63 (range 19–125) bacterial species. Severe DFIs had complex microbiomes and were distinctly dissimilar to less severe infections (p = 0.02), characterised by the presence of low frequency microorganisms. Nineteen patients (49%) during the study period experienced antimicrobial treatment failure, but no overall differences existed in the microbiome of patients who failed therapy and those who experienced treatment success (p = 0.2). Our results confirm that short DFUs have a simpler microbiome consisting of pyogenic cocci but chronic DFUs have a highly polymicrobial microbiome. The duration of a DFU may be useful as a guide to directing antimicrobial therapy.

Surfactants and their role in wound cleansing and biofilm management

Surfactants are widely used as detergents, emulsifiers, wetting agents, foaming agents and dispersants in the cosmetics, hygiene, food and oil industries. Their use in a clinical setting is also common, particularly within the field of wound care. Many wound cleansers contain surfactants and subsequently there is available data that shows the growing potential of these wound cleansers in the enhancement of wound closure. The presence of microorganisms in wounds has been recognised as a significant factor that delay healing. In complex or chronic wounds that are complicated by biofilms, persistent inflammation or the production of non-viable tissue and slough, the use of surfactants has been shown to aid in the removal of these barriers to wound healing. The use of concentrated surfactant(poloxamer) based wound dressings represent an important component of wound management. Consequently, this article will discuss the effect of clinically used surfactants, with specific focus on a concentrated poloxamer for use against wound biofilm.

Diabetic Foot Australia guideline on footwear for people with diabetes

BackgroundThe aim of this paper was to create an updated Australian guideline on footwear for people with diabetes.MethodsWe reviewed new footwear publications, (inter)national guidelines, and consensus expert opinion alongside the 2013 Australian footwear guideline to formulate updated recommendations.ResultWe recommend health professionals managing people with diabetes should: (1) Advise people with diabetes to wear footwear that fits, protects and accommodates the shape of their feet. (2) Advise people with diabetes to always wear socks within their footwear, in order to reduce shear and friction. (3) Educate people with diabetes, their relatives and caregivers on the importance of wearing appropriate footwear to prevent foot ulceration. (4) Instruct people with diabetes at intermediate- or high-risk of foot ulceration to obtain footwear from an appropriately trained professional to ensure it fits, protects and accommodates the shape of their feet. (5) Motivate people with diabetes at intermediate- or high-risk of foot ulceration to wear their footwear at all times, both indoors and outdoors. (6) Motivate people with diabetes at intermediate- or high-risk of foot ulceration (or their relatives and caregivers) to check their footwear, each time before wearing, to ensure that there are no foreign objects in, or penetrating, the footwear; and check their feet, each time their footwear is removed, to ensure there are no signs of abnormal pressure, trauma or ulceration. (7) For people with a foot deformity or pre-ulcerative lesion, consider prescribing medical grade footwear, which may include custom-made in-shoe orthoses or insoles. (8) For people with a healed plantar foot ulcer, prescribe medical grade footwear with custom-made in-shoe orthoses or insoles with a demonstrated plantar pressure relieving effect at high-risk areas. (9) Review prescribed footwear every three months to ensure it still fits adequately, protects, and supports the foot. (10) For people with a plantar diabetic foot ulcer, footwear is not specifically recommended for treatment; prescribe appropriate offloading devices to heal these ulcers.ConclusionsThis guideline contains 10 key recommendations to guide health professionals in selecting the most appropriate footwear to meet the specific foot risk needs of an individual with diabetes.