Clinical management of chronic wound infections: The battle against biofilm.

Bacteria constitute the most abundant life form on earth, of which the majority exist in a protective biofilm state. Since the 1980s, we have learned much about the role of biofilm in human chronic infections, with associated global healthcare costs recently estimated at ~$386 billion. Chronic wound infection is a prominent biofilm-induced condition that is characterised by persistent inflammation and associated host tissue destruction, and clinical signs that are distinct from signs of acute wound infection.

A review of iodine-based compounds, with a focus on biofilms: results of an expert panel.

Biofilms play a central role in the chronicity of non-healing lesions such as venous leg ulcers and diabetic foot ulcers. Therefore, biofilm management and treatment is now considered an essential part of wound care. Many antimicrobial treatments, whether topical or systemic, have been shown to have limited efficacy in the treatment of biofilm phenotypes.

Patient genetics is linked to chronic wound microbiome composition and healing.

The clinical importance of microbiomes to the chronicity of wounds is widely appreciated, yet little is understood about patient-specific processes shaping wound microbiome composition. Here, a two-cohort microbiome-genome wide association study is presented through which patient genomic loci associated with chronic wound microbiome diversity were identified. Further investigation revealed that alternative TLN2 and ZNF521 genotypes explained significant inter-patient variation in relative abundance of two key pathogens, Pseudomonas aeruginosa and Staphylococcus epidermidis.

Chronic wound microbiome colonization on mouse model following cryogenic preservation.

Chronic wound infections are increasingly recognized to be dynamic and polymicrobial in nature, necessitating the development of wound models which reflect the complexities of infection in a non-healing wound. Wound slough isolated from human chronic wounds and transferred to mice was recently shown to create polymicrobial infection in mice, and there is potential this tool may be improved by cryogenic preservation. The purpose of this study was to investigate the application of cryogenic preservation to transferring polymicrobial communities, specifically by quantifying the effects of cryopreservation and wound microbiome transplantation.

Bacterial fitness in chronic wounds appears to be mediated by the capacity for high-density growth, not virulence or biofilm functions.

While much is known about acute infection pathogenesis, the understanding of chronic infections has lagged. Here we sought to identify the genes and functions that mediate fitness of the pathogen Pseudomonas aeruginosa in chronic wound infections, and to better understand the selective environment in wounds. We found that clinical isolates from chronic human wounds were frequently defective in virulence functions and biofilm formation, and that many virulence and biofilm formation genes were not required for bacterial fitness in experimental mouse wounds.

Consensus guidelines for the identification and treatment of biofilms in chronic nonhealing wounds.

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.

Temporal dynamics of relative abundances and bacterial succession in chronic wound communities.

Polymicrobial bacterial infection is an important factor contributing to wound chronicity. Consequently, clinicians frequently adopt a biofilm-based wound care approach, in which wounds are treated utilizing DNA sequencing information about microbial communities. While more successful than treatment not using community information, there is little information about temporal dynamics of wound communities and optimal approaches over the course of treatment.

A post-planktonic era of in vitro infectious models: issues and changes addressed by a clinically relevant wound like media.

Medical science is pitted against an ever-increasing rise in antibiotic tolerant microorganisms. Concurrently, during the past decade, biofilms have garnered much attention within research and clinical practice. Although the significance of clinical biofilms is becoming very apparent, current methods for diagnostics and direction of therapy plans in many hospitals do not reflect this knowledge; with many of the present tools proving to be inadequate for accurately mimicking the biofilm phenomenon.

Analysis of the chronic wound microbiota of 2,963 patients by 16S rDNA pyrosequencing.

The extent to which microorganisms impair wound healing is an ongoing controversy in the management of chronic wounds. Because the high diversity and extreme variability of the microbiota between individual chronic wounds lead to inconsistent findings in small cohort studies, evaluation of a large number of chronic wounds using identical sequencing and bioinformatics methods is necessary for clinicians to be able to select appropriate empiric therapies. In this study, we utilized 16S rDNA pyrosequencing to analyze the composition of the bacterial communities present in samples obtained from patients with chronic diabetic foot ulcers (N = 910), venous leg ulcers (N = 916), decubitus ulcers (N = 767), and nonhealing surgical wounds (N = 370).

Clinical identification of bacteria in human chronic wound infections: culturing vs. 16S ribosomal DNA sequencing.

Background: Chronic wounds affect millions of people and cost billions of dollars in the United States each year. These wounds harbor polymicrobial biofilm communities, which can be difficult to elucidate using culturing methods. Clinical molecular microbiological methods are increasingly being employed to investigate the microbiota of chronic infections, including wounds, as part of standard patient care.

Direct sampling of cystic fibrosis lungs indicates that DNA-based analyses of upper-airway specimens can misrepresent lung microbiota.

Recent work using culture-independent methods suggests that the lungs of cystic fibrosis (CF) patients harbor a vast array of bacteria not conventionally implicated in CF lung disease. However, sampling lung secretions in living subjects requires that expectorated specimens or collection devices pass through the oropharynx. Thus, contamination could confound results.

The effect of a hydroconductive dressing on the suppression of wound biofilm.

Unlabelled: Although excessive exudate has been associated with poor wound healing outcomes, exudate is still not well understood in the pathophysiology of chronic wounds. Wound exudate is believed to be the result of wounds that are trapped in a persistent, hyper inflammatory state. Biofilm, bacteria of multiple species living in community, has multiple well-defined molecular pathways that produce hyper inflammation.

Comparison of culture and molecular identification of bacteria in chronic wounds.

Clinical diagnostics of chronic polymicrobial infections, such as those found in chronic wounds, represent a diagnostic challenge for both culture and molecular methods. In the current retrospective study, the results of aerobic bacterial cultures and culture-free bacterial identification using DNA analyses were compared. A total of 168 chronic wounds were studied.

An in vivo polymicrobial biofilm wound infection model to study interspecies interactions.

Chronic wound infections are typically polymicrobial; however, most in vivo studies have focused on monospecies infections. This project was designed to develop an in vivo, polymicrobial, biofilm-related, infected wound model in order to study multispecies biofilm dynamics and in relation to wound chronicity. Multispecies biofilms consisting of both Gram negative and Gram positive strains, as well as aerobes and anaerobes, were grown in vitro and then transplanted onto the wounds of mice.

Tag-encoded FLX amplicon pyrosequencing for the elucidation of microbial and functional gene diversity in any environment.

Comprehensive evaluation of microbial diversity in almost any environment is now possible. Questions such as "Does the addition of fiber to the diet of humans change the gastrointestinal microbiota?" can now be answered easily and inexpensively. Tag-encoded FLX-amplicon pyrosequencing (TEFAP) has been utilized to evaluate bacterial, archaeal, fungal, algal, as well as functional genes.

Black Box Chimera Check (B2C2): a Windows-Based Software for Batch Depletion of Chimeras from Bacterial 16S rRNA Gene Datasets.

The existing chimera detection programs are not specifically designed for "next generation" sequence data. Technologies like Roche 454 FLX and Titanium have been adapted over the past years especially with the introduction of bacterial tag-encoded FLX/Titanium amplicon pyrosequencing methodologies to produce over one million 250-600 bp 16S rRNA gene reads that need to be depleted of chimeras prior to downstream analysis. Meeting the needs of basic scientists who are venturing into high-throughput microbial diversity studies such as those based upon pyrosequencing and specifically providing a solution for Windows users, the B2C2 software is designed to be able to accept files containing large multi-FASTA formatted sequences and screen for possible chimeras in a high throughput fashion.

Evaluation of the bacterial diversity of pressure ulcers using bTEFAP pyrosequencing.

Background: Decubitus ulcers, also known as bedsores or pressure ulcers, affect millions of hospitalized patients each year. The microflora of chronic wounds such as ulcers most commonly exist in the biofilm phenotype and have been known to significantly impair normal healing trajectories.

Methods: Bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP), a universal bacterial identification method, was used to identify bacterial populations in 49 decubitus ulcers.

Pyrosequencing study of fecal microflora of autistic and control children.

There is evidence of genetic predisposition to autism, but the percent of autistic subjects with this background is unknown. It is clear that other factors, such as environmental influences, may play a role in this disease. In the present study, we have examined the fecal microbial flora of 33 subjects with various severities of autism with gastrointestinal symptoms, 7 siblings not showing autistic symptoms (sibling controls) and eight non-sibling control subjects, using the bacterial tag encoded FLX amplicon pyrosequencing (bTEFAP) procedure.

A comparison of bacterial composition in diabetic ulcers and contralateral intact skin.

An extensive portion of the healthcare budget is allocated to chronic human infection. Chronic wounds in particular are a major contributor to this financial burden. Little is known about the types of bacteria which may contribute to the chronicity, biofilm and overall bioburden of the wound itself.

Molecular characterization of the polymicrobial flora in chronic rhinosinusitis.

Introduction: Conventional cultures have implicated Staphylococcus aureus (SA) and coagulase-negative Staphylococcus (CNS) as principal pathogens in chronic rhinosinusitis (CRS). These results are questioned by recent studies in which molecular probes implicate Haemophilus influenzae instead.

Objectives: To identify all bacterial species present on sinonasal mucosa using molecular culture (bacterial tag-encoded FLX amplicon pyrosequencing [bTEFAP]) and to compare them with those identified with conventional methods.

Microarray analysis and draft genomes of two Escherichia coli O157:H7 lineage II cattle isolates FRIK966 and FRIK2000 investigating lack of Shiga toxin expression.

The existence of two separate genetic lineages of Escherichia coli O157:H7 has previously been reported, and research indicates that lineage I could be more pathogenic toward human hosts than lineage II. We have previously shown that lineage I as a group expresses higher levels of Shiga toxin 2 (Stx2) than lineage II. To help evaluate why lineage II strains do not express appreciable levels of this toxin, whole-genome microarrays were performed using Agilent custom microarrays.

Evaluation of the bacterial diversity among and within individual venous leg ulcers using bacterial tag-encoded FLX and titanium amplicon pyrosequencing and metagenomic approaches.

Background: Approximately 1 out of every 100 individuals has some form of venous insufficiency, which can lead to chronic venous disease and Venous Leg Ulcer (VLU). There are known underlying pathologies which contribute to the chronic nature of VLU including biofilm phenotype infections.

Results: Using pyrosequencing based approaches we evaluated VLU to characterize their microbial ecology.

In vitro multispecies Lubbock chronic wound biofilm model.

Multispecies biofilms are becoming increasingly recognized as the naturally occurring state in which bacteria reside. One of the primary health issues that is now recognized to be exacerbated by biofilms are chronic, nonhealing wounds such as venous leg ulcers, diabetic foot ulcers, and pressure ulcers. Arguably three of the most important species associated with multispecies biofilms that our group sees clinically are Pseudomonas aeruginosa, Enterococcus faecalis, and Staphylococcus aureus.

In vitro susceptibility of established biofilms composed of a clinical wound isolate of Pseudomonas aeruginosa treated with lactoferrin and xylitol.

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.