Wound Microbiota Research Articles

Relationship Between Dysbiotic Wound Microbiota and Critical Colonization: Involvement of FOXP3-Positive Cells in Rats.

Detection of critical colonization is gaining importance in wound management, but its pathophysiology remains unclear. We previously clarified that a dysbiotic wound microbiota differing from skin commensal microbiota may be involved in critical colonization and that such wounds contain fewer Forkhead box protein P3 (FOXP3)-positive cells in the tissue. However, it is not clear whether FOXP3-positive cells contribute to the development of critical colonization. Here, we examined whether inhibition of FOXP3-positive cell could induce critical colonization when the commensal microbiota was present in the wounds. Sprague-Dawley rats were administered FK506 or vehicle to inhibit differentiation into FOXP3-positive cells. Full-thickness wounds were made on the dorsal skin and inoculated with bacterial solution (dysbiosis group) or Luria-Bertani medium (commensal group). A bacterial solution was prepared by anaerobically culturing bacteria from the skin of donor rats on an artificial dermis in Luria-Bertani medium for 72 hours. Tissues were collected on day 4 postwounding for histological evaluation. After microbiota transplantation, excessive inflammation occurred in the FK506 + commensal group. In contrast, wounds with transplanted dysbiotic microbiota showed the same level of neutrophil infiltration, regardless of FK506 administration. Furthermore, the wound area was larger in the FK506 + commensal group than in the vehicle + commensal group on day 4 postwounding (P = 0.01). This area was also significantly larger in both the vehicle + dysbiosis (P = 0.01) and FK506 + dysbiosis groups (P = 0.03) than in the vehicle + commensal group. This study has shown that dysbiosis may be at least related to developing critical colonization, and the results suggest that FOXP3-positive cells are involved in this process. Our study may contribute to establishing new interventions that prevent critical colonization by correcting wound microbiota.

Sequence analysis of microbiota in clinical human cases with diabetic foot ulcers from China

BackgroundDiabetic foot ulcers (DFU) seriously threaten the health and quality of life of patients. The microbiota is the primary reason for the refractory and high recurrence of DFU. This study aimed to determine the wound microbiota at different DFU stages. MethodsWound samples were collected from 48 patients with DFU and divided into three phases: inflammatory (I, n = 49), proliferation (P, n = 22), and remodeling (R, n = 19). The wound samples obtained at different stages were then subjected to 16S rRNA gene sequencing. The number of operational taxonomic units (OTUs) in the different groups was calculated according to the criterion of 97 % sequence similarity. The diversity of the microbiota differentially presented bacterial taxa at the phylum and genus levels, and important phyla and genera in the different groups were further explored. ResultsAfter sequencing, 3351, 925, and 777 OTUs were observed in groups I, P, and R, respectively, and 175 OTUs overlapped. Compared with the inflammatory stage, the α-diversity of wound microbiota at proliferation and remodeling stages was significantly decreased (P < 0.05). At the phylum level, Firmicutes, Proteobacteria, Actinobacteriota, and Bacteroidota were the dominant phyla, accounting for more than 90 % of all the phyla. At the genus level, Random Forest and linear discriminant analysis effect size analyses showed that Peptoniphilus, Lactobacillus, Prevotella, Veillonella, Dialister, Streptococcus, and Ruminococcus were the signature wound microbiota for the inflammatory stage; Anaerococcus, Ralstonia, Actinomyces, and Akkermansia were important species for the proliferation stage; and the crucial genera for the remodeling stage were Enterobacter, Pseudomonas, Sondgrassella, Bifidobacterium, and Faecalibacterium. ConclusionsThere were significant differences in the composition and structure of the wound microbiota in patients with DFU at different stages, which may lay a foundation for effectively promoting wound healing in DFU.

The heterogeneous wound microbiome varies with wound care pain, dressing type, and inflammatory gene expression.

Wound dressing changes are essential procedures for wound management. However, ~50% of patients experience severe pain during these procedures despite the availability of analgesic medications, indicating a need for novel therapeutics that address underlying causes of pain. Along with other clinical factors, wound pathogens and inflammatory immune responses have previously been implicated in wound pain. To test whether these factors could contribute to severe pain during wound dressing changes, we conducted an exploratory, cross-sectional analysis of patient-reported pain, inflammatory immune responses, and wound microbiome composition in 445 wounds at the time of a study dressing change. We profiled the bacterial composition of 406 wounds using 16S ribosomal RNA amplicon sequencing and quantified gene expression of 13 inflammatory markers in wound fluid using quantitative real-time polymerase chain reaction (qPCR). Neither inflammatory gene expression nor clinically observed inflammation were associated with severe pain, but Corynebacterium and Streptococcus were of lower relative abundance in wounds of patients reporting severe pain than those reporting little or no pain. Wound microbiome composition differed by wound location, and correlated with six of the inflammatory markers, including complement receptor C5AR1, pro-inflammatory cytokine interleukin (IL)1β, chemokine IL-8, matrix metalloproteinase MMP2, and the antimicrobial peptide encoding cathelicidin antimicrobial peptide. Interestingly, we found a relationship between the wound microbiome and vacuum-assisted wound closure (VAC). These findings identify preliminary, associative relationships between wound microbiota and host factors which motivate future investigation into the directional relationships between wound care pain, wound closure technologies, and the wound microbiome.

Photopolymerizable and Antibacterial Hydrogels Loaded with Metabolites from Lacticaseibacillus rhamnosus GG for Infected Wound Healing.

In response to increasing antibiotic resistance and the pressing demand for safer infected wound care, probiotics have emerged as promising bioactive agents. To address the challenges associated with the safe and efficient application of probiotics, this study successfully loaded metabolites from Lacticaseibacillus rhamnosus GG (LGG) into a gelatin cross-linked macromolecular network by an in situ blending and photopolymerization method. The obtained LM-GelMA possesses injectability and autonomous healing capabilities. Importantly, the incorporation of LGG metabolites endows LM-GelMA with excellent antibacterial properties against Staphylococcus aureus and Escherichia coli, while maintaining good biocompatibility. In vivo assessments revealed that LM-GelMA can accelerate wound healing by mitigating infections induced by pathogenic bacteria. This is accompanied by a reduction in the expression of key proinflammatory cytokines such as TNF-α, IL-6, VEGFR2, and TGF-β, leading to increased re-epithelialization and collagen formation. Moreover, microbiological analysis confirmed that LM-GelMA can modulate the abundance of beneficial wound microbiota at family and genus levels. This study provides a facile strategy and insights into the functional design of hydrogels from the perspective of wound microenvironment regulation.

Application effect of a dual release system of androgen and its antagonist in the repair of full-thickness burn wounds in mice

Application effect of a dual release system of androgen and its antagonist in the repair of full-thickness burn wounds in mice

Wound healing of experimental equine skin wounds and concurrent microbiota in wound dressings following topical propylene glycol gel treatment.

Topical wound treatments rely on carrier formulations with little to no biological impact. The potential for a common vehicle, a propylene glycol (PG) gel, to affect wound healing measures including microbiota is not known. Microbiome characterization, based on next generation sequencing methods is typically performed on tissue or directly obtained wound fluid samples. The utility for primary wound dressings to characterize equine wound microbiota in the context of topical treatments is currently unknown. This investigation reports the topical effect of an 80% PG based gel on wound healing and microbiota in wound dressings. Experiments were performed in six mature horses utilizing a surgical, distal limb wound model, histology of sequential wound biopsies, photographic wound measurements and microbiota profiling via 16s rRNA sequencing of wound dressing samples. Experimental wounds were surveyed for 42 days and either treated (Day 7, 14, 21 and 28; at 0.03 ml/cm2) or unexposed to the PG gel. Wound surface area, relative and absolute microbial abundances, diversity indices and histologic parameters were analyzed in the context of the experimental group (treatment; control) using qualitative or quantitative methods depending on data characteristics. Compared to controls, treatment slowed the wound healing rate (17.17 ± 4.27 vs. 18.56 ± 6.3 mm2/day), delayed the temporal decline of polymorphonucleated cells in wound beds and operational taxonomic units (OTU) in wound dressings and lowered alpha-diversity indices for microbiota in primary wound dressing. Relative abundances of OTUs were in line with those previously reported for equine wounds. Clinical outcomes 42 days post wounding were considered similar irrespective of PG gel exposure. Results highlight the potential for vehicle exposure to alter relevant wound outcome measures, imposing the need for stringent experimental control measures. Primary wound dressings may represent an alternate sample source for characterization of the wound microbiome alleviating the need for additional interventions. Further studies are warranted to contrast the microbiome in wound dressings against that present on wound surfaces to conclude on the validity of this approach.

Wound Microbiota and Its Impact on Wound Healing.

Wound healing is a complex process influenced by age, systemic conditions, and local factors. The wound microbiota's crucial role in this process is gaining recognition. This concise review outlines wound microbiota impacts on healing, emphasizing distinct phases like hemostasis, inflammation, and cell proliferation. Inflammatory responses, orchestrated by growth factors and cytokines, recruit neutrophils and monocytes to eliminate pathogens and debris. Notably, microbiota alterations relate to changes in wound healing dynamics. Commensal bacteria influence immune responses, keratinocyte growth, and blood vessel development. For instance, Staphylococcus epidermidis aids keratinocyte progression, while Staphylococcus aureus colonization impedes healing. Other bacteria like Group A Streptococcus spp. And Pseudomonas affect wound healing as well. Clinical applications of microbiota-based wound care are promising, with probiotics and specific bacteria like Acinetobacter baumannii aiding tissue repair through molecule secretion. Understanding microbiota influence on wound healing offers therapeutic avenues. Tailored approaches, including probiotics, prebiotics, and antibiotics, can manipulate the microbiota to enhance immune modulation, tissue repair, and inflammation control. Despite progress, critical questions linger. Determining the ideal microbiota composition for optimal wound healing, elucidating precise influence mechanisms, devising effective manipulation strategies, and comprehending the intricate interplay between the microbiota, host, and other factors require further exploration.

Indicators of the immune status in patients with chronic wounds depending on the stage of the infectious process and the structure of the wound microbiota

The results of immunophenotyping of peripheral blood leukocytes were analyzed in 105 patients with chronic wounds ( the main group , wound duration more than 3 weeks ) at various stages of the infectious process : colonization (n=39), critical colonization (n=37) and infection (n=29). The comparison group consisted of 22 patients with acute wounds ( wound duration up to 4 days ), in which microorganisms were not detected in the wounds . In the main group , changes in immunological reactivity were revealed in the form of an increase in the relative content of T- lymphocytes and a decrease in NK cells , lower indicators of early activation markers on T- helpers and T- cytotoxic lymphocytes (CD4+/CD38+/CD3+, CD8+/CD38+/CD3+, CD3+/ CD71+) and HLADR on B- lymphocytes , a high level of expression of late markers of T- cell activation (CD3+HLADR+). In the comparison group , the levels of expression of integrins (CD11a, CD11b, CD11c) on neutrophils and lymphocytes , as well as the transferrin receptor (CD71) on neutrophils , monocytes and lymphocytes were higher than in the main group . An increase in the activity of neutrophils in the form of expression of CD11a molecules was revealed with the progression of the infectious process in a chronic wound , which may be an additional diagnostic sign of the transition from the stage of colonization to the stage of critical colonization and infection . The highest values of CD11a and CD11c on neutrophils were recorded in the presence of S. aureus monocultures in chronic wounds , the lowest values were recorded when P. aeruginosa and A. baumannii monocultures were isolated from wounds .

Relationship between healing status and microbial dissimilarity in wound and peri-wound skin in pressure injuries

AimWound infection is the most serious cause of delayed healing for patients with pressure injuries. The wound microbiota, which plays a crucial role in delayed healing, forms by bacterial dissemination from the peri-wound skin. To manage the bioburden, wound and peri-wound skin care has been implemented; however, how the microbiota at these sites contribute to delayed healing is unclear. Therefore, we investigated the relationship between healing status and microbial dissimilarity in wound and peri-wound skin. MethodsA prospective cohort study was conducted at a long-term care hospital. The outcome was healing status assessed using the DESIGN-R® tool, a wound assessment tool to monitor the wound healing process. Bacterial DNA was extracted from the wound and peri-wound swabs, and microbiota composition was analyzed using 16S rRNA gene analysis. To evaluate microbial similarity, the weighted UniFrac dissimilarity index between wound and peri-wound microbiota was calculated. ResultsTwenty-two pressure injuries (7 deep and 15 superficial wounds) were included in the study. For deep wounds, the predominant bacteria in wound and peri-wound skin were the same in the healing wounds, whereas they were different in all cases of hard-to-heal wounds. Analysis based on the weighted UniFrac dissimilarity index, there was no significant difference for healing wounds (p = 0.639), while a significant difference was found for hard-to-heal wounds (p = 0.047). ConclusionsDelayed healing is possibly associated with formation of wound microbiota that is different in composition from that of the skin commensal microbiota. This study provides a new perspective for assessing wound bioburden.

Effect of Polarized Light Therapy (Bioptron) on Wound Healing and Microbiota in Diabetic Foot Ulcer: A Randomized Controlled Trial.

Background: Diabetic foot ulcer (DFU) complications are the most common cause of morbidity in diabetic patients. Bioptron light therapy is a new adjuvant therapy for wound healing. This study aimed to investigate the effect of polarized light therapy on the healing and microbial nature of DFUs. Methods: Forty type 2 diabetic patients with Wagner grade 1 or 2 DFUs were randomly assigned to one of two groups: the light therapy group, which received Bioptron light therapy using the Bioptron lamp for 12 min three times per week, plus standard wound care, or the control group, which received standard wound care only. Both interventions were given over a 2-month period. Wound surface area, volume, and ulcer microbial cultures were all measured before and after the study period. Results: There was a significant reduction in ulcer surface area between groups in favor of the light therapy group, with a relative ulcer size reduction of 51.44% ± 23.76% compared with 24.5% ± 9.6% in the control group (p < 0.001). Besides, a significant difference was observed between groups in the microbial cultures (p = 0.02); by the end of the 8th week, the number of patients with negative ulcer culture was 12 (60%) in the light therapy group compared with 3 (15%) in the control group. Conclusions: Bioptron light therapy seems to be an effective therapeutic intervention combined with standard care in decreasing wound size and reducing ulcer microbiota for DFUs. It reduces ulcer bacterial infection and speeds up ulcer healing. Trial registration: ClinicalTrials.gov: NCT04446767.

An in vivo critically colonised wound model with dysbiotic wound microbiota.

In critically colonised wounds, many of the signs of infection are often absent, and delayed healing may be the only clinical sign. The prevention of critical colonisation is important, but its pathophysiology has not yet been elucidated. We have previously reported that dysbiotic microbiota dissimilar to the peri-wound skin microbiota may develop in critically colonised wounds. To investigate the role of dysbiotic microbiota, this study aimed to develop a critically colonised wound model by transplantation of dysbiotic microbiota. To transplant microbiota, a bacterial solution (dysbiosis group) or with Luria-Bertani medium (commensal group) was inoculated to full-thickness wounds of rats. The bacterial solution was prepared by anaerobically culturing bacteria from donor rats on an artificial dermis in Luria-Bertani medium for 72 hours. As a result, the degree of the change in the microbial similarity between pre- and post-transplantation of microbiota was significantly higher in the dysbiosis group (P< .001). No signs of infection were observed in any rat in either group. The wound area in the dysbiosis group was significantly larger (P< .001), and there was a significant infiltration of neutrophils (P< .001). All rats of the dysbiosis group represented the clinical features of critically colonised wounds. Furthermore, there were significantly fewer regulatory T cells in the wounds of the dysbiosis group. This is the first study to develop a novel animal model that represents the clinical features of critically colonised wounds and will be useful in investigating the pathogenesis of critical colonisation via regulatory T cells.

Novel Diagnostic Technologies and Therapeutic Approaches Targeting Chronic Wound Biofilms and Microbiota.

To provide an up-to-date overview of recent developments in diagnostic methods and therapeutic approaches for chronic wound biofilms and pathogenic microbiota. Biofilm infections are one of the major contributors to impaired wound healing in chronic wounds, including diabetic foot ulcers, venous leg ulcers, pressure ulcers, and nonhealing surgical wounds. As an organized microenvironment commonly including multiple microbial species, biofilms develop and persist through methods that allow evasion from host immune response and antimicrobial treatments. Suppression and reduction of biofilm infection have been demonstrated to improve wound healing outcomes. However, chronic wound biofilms are a challenge to treat due to limited methods for accurate, accessible clinical identification and the biofilm's protective properties against therapeutic agents. Here we review recent approaches towards visual markers for less invasive, enhanced biofilm detection in the clinical setting. We outline progress in wound care treatments including investigation of their antibiofilm effects, such as with hydrosurgical and ultrasound debridement, negative pressure wound therapy with instillation, antimicrobial peptides, nanoparticles and nanocarriers, electroceutical dressings, and phage therapy. Current evidence for biofilm-targeted treatments has been primarily conducted in preclinical studies, with limited clinical investigation for many therapies. Improved identification, monitoring, and treatment of biofilms require expansion of point-of-care visualization methods and increased evaluation of antibiofilm therapies in robust clinical trials.

Oral nanotherapeutics based on Antheraea pernyi silk fibroin for synergistic treatment of ulcerative colitis

Ulcerative colitis (UC) with its rapidly increasing incidence has become an emerging challenge for public health. Therapeutic agents are required to be specifically delivered to colon epithelial cells and macrophages with controlled release in the cytoplasm for wound healing, inflammation alleviation, and microbiota rebalance. As a promising biomaterial for accomplishing this, Antheraea pernyi silk fibroin (ApSF) was selected and engineered to form nanoparticles (NPs) loaded with the anti-inflammatory drug, resveratrol (Res). The intrinsic features of these fabricated Res-ApNPs included targeting of colonic epithelial cells and macrophages, lysosomal escape capacity, and responsiveness to pH, reactive oxygen species (ROS), and glutathione, which were pertinent to their functional units such as arginine-glycine-aspartate tripeptides, α-helixes, β-sheets, and disulfide bonds, enabling on-demand release of Res molecules in the cytoplasm of target cells. The Res-ApNP treatment restored damaged colonic epithelial barriers, polarized macrophages to type M2, alleviated inflammatory reactions, and reduced the level of intracellular ROS. Oral treatment with chitosan-alginate hydrogels embedded with Res-ApNPs substantially relieved UC symptoms, as evidenced by decreased colonic inflammation, increased synthesis of tight-junction proteins, and rebalanced intestinal microbiota. Our findings suggest that these high-performance ApSF-based NPs can be developed as effective drug carriers for oral UC treatment.

Comparison Between Cultivation and Sequencing Based Approaches for Microbiota Analysis in Swabs and Biopsies of Chronic Wounds.

Chronic wounds are a prominent health concern affecting 0.2% of individuals in the Western population. Microbial colonization and the consequent infection contribute significantly to the healing process. We have compared two methods, cultivation and 16S amplicon sequencing (16S-AS), for the characterization of bacterial populations in both swabs and biopsy tissues obtained from 45 chronic wounds. Using cultivation approach, we detected a total of 39 bacterial species, on average 2.89 per sample (SD = 1.93), compared to 5.9 (SD = 7.1) operational taxonomic units per sample obtained with 16S-AS. The concordance in detected bacteria between swab and biopsy specimens obtained from the same CWs was greater when using cultivation (58.4%) as compared to 16S-AS (25%). In the entire group of 45 biopsy samples concordance in detected bacterial genera between 16S-AS and cultivation-based approach was 36.4% and in swab samples 28.7%. Sequencing proved advantageous in comparison to the cultivation mainly in case of highly diverse microbial communities, where we could additionally detect numerous obligate and facultative anaerobic bacteria from genera Anaerococcus, Finegoldia, Porphyromonas, Morganella, and Providencia. Comparing swabs and biopsy tissues we concluded, that neither sampling method shows significant advantage over the other regardless of the method used (16S-AS or cultivation). In this study, chronic wound microbiota could be distributed into three groups based on the bacterial community diversity. The chronic wound surface area was positively correlated with bacterial diversity in swab specimens but not in biopsy tissues. Larger chronic wound surface area was also associated with the presence of Pseudomonas in both biopsy and swab specimens. The presence of Corynebacterium species at the initial visit was the microbial marker most predictive of the unfavorable clinical outcome after one-year follow-up visit.

Factors related to the composition and diversity of wound microbiota investigated using culture-independent molecular methods: a scoping review.

All open wounds are often colonized by commensal microbes as a loss of skin can provide a ready portal of entry for microorganisms. Although the wound microbiota is known to be associated with wound infection and with delayed healing, the factors related to the formations of wound microbiota contributing to such poor clinical outcomes are not clear and have not led to effective infection prevention interventions. This review aimed to scope the factors related to the composition and diversity of wound microbiota that have been investigated using culture-independent molecular methods. Original articles on wound microbiota published from January 1986 to February 2020 were included in this review. Thirty-one articles met the inclusion criteria and were grouped according to wound types: chronic, acute, and animal model wounds. The factors identified were categorized according to patient characteristics, wound characteristics, treatment, and sampling. Although some studies reported the effect size of the factors, the values were small. No studies elucidated the mechanism of wound microbiota formation. The results of this scoping review highlight that the factors associated with the diversity of wound microbiota are poorly understood and that further studies are needed.

Skin Microbiota and its Interplay with Wound Healing.

The skin microbiota is intimately coupled with cutaneous health and disease. Interactions between commensal microbiota and the multiple cell types involved in cutaneous wound healing regulate the immune response and promote barrier restoration. This dialog between host cells and the microbiome is dysregulated in chronic wounds. In this review, we first describe how advances in sequencing approaches and analysis have been used to study the chronic wound microbiota, and how these findings underscored the complexity of microbial communities and their association with clinical outcomes in patients with chronic wound disorders. We also discuss the mechanistic insights gathered from multiple animal models of polymicrobial wound infections. In addition to the well-described role of bacteria residing in polymicrobial biofilms, we also discuss the role of the intracellular bacterial niche in wound healing. We describe how, in contrast to pathogenic species capable of subverting skin immunity, commensals are essential for the regulation of the cutaneous immune system and provide protection from intracellular pathogens through modulation of the antimicrobial molecule, Perforin-2. Despite recent advances, more research is needed to shed light on host-microbiome crosstalk in both healing and nonhealing chronic wounds to appropriately guide therapeutic developments.

High Levels of Oxidative Stress Create a Microenvironment That Significantly Decreases the Diversity of the Microbiota in Diabetic Chronic Wounds and Promotes Biofilm Formation.

Diabetics chronic wounds are characterized by high levels of oxidative stress (OS) and are often colonized by biofilm-forming bacteria that severely compromise healing and can result in amputation. However, little is known about the role of skin microbiota in wound healing and chronic wound development. We hypothesized that high OS levels lead to chronic wound development by promoting the colonization of biofilm-forming bacteria over commensal/beneficial bacteria. To test this hypothesis, we used our db/db−/− mouse model for chronic wounds where pathogenic biofilms develop naturally after induction of high OS immediately after wounding. We sequenced the bacterial rRNA internal transcribed spacer (ITS) gene of the wound microbiota from wound initiation to fully developed chronic wounds. Indicator species analysis, which considers a species' fidelity and specificity, was used to determine which bacterial species were strongly associated with healing wounds or chronic wounds. We found that healing wounds were colonized by a diverse and dynamic bacterial microbiome that never developed biofilms even though biofilm-forming bacteria were present. Several clinically relevant species that are present in human chronic wounds, such as Cutibacterium acnes, Achromobacter sp., Delftia sp., and Escherichia coli, were highly associated with healing wounds. These bacteria may serve as bioindicators of healing and may actively participate in the processes of wound healing and preventing pathogenic bacteria from colonizing the wound. In contrast, chronic wounds, which had high levels of OS, had low bacterial diversity and were colonized by several clinically relevant, biofilm-forming bacteria such as Pseudomonas aeruginosa, Enterobacter cloacae, Corynebacterium frankenforstense, and Acinetobacter sp. We observed unique population trends: for example, P. aeruginosa associated with aggressive biofilm development, whereas Staphylococcus xylosus was only present early after injury. These findings show that high levels of OS in the wound significantly altered the bacterial wound microbiome, decreasing diversity and promoting the colonization of bacteria from the skin microbiota to form biofilm. In conclusion, bacteria associated with non-chronic or chronic wounds could function as bioindicators of healing or non-healing (chronicity), respectively. Moreover, a better understanding of bacterial interactions between pathogenic and beneficial bacteria within an evolving chronic wound microbiota may lead to better solutions for chronic wound management.

Epidermal growth factor vs platelet-rich plasma: Activity against chronic wound microbiota.

The objective was to evaluate Staphylococcus aureus and Pseudomonas aeruginosa colonisation of wounds treated with recombinant epidermal growth factor (EGF) and platelet-rich plasma (PRP); to analyse the susceptibility profiles of S. aureus and P. aeruginosa isolates from wounds treated with EGF and PRP; and to describe the presence of infection in EGF-treated and PRP-treated wounds. Experimental study was performed using clinical specimens collected with swabs. Patients were treated with PRP and EGF in the outpatient clinic of a university hospital. Forty-three isolates were obtained from 31 patients, 41.9% (13/31) of whom had been treated with EGF and 58.0% (18/31) with PRP. Ten of the 43 isolates were identified as S. aureus, 60.0% (6/10) of which were isolated from PRP-treated wounds. Among the 33 P. aeruginosa isolates, 66.6% (22/33) were isolated from PRP-treated wounds. Regarding antimicrobial susceptibility, only one strain isolated from an EGF-treated wound was identified as methicillin-resistant S. aureus (MRSA). Among the P. aeruginosa isolates, one obtained from a patient treated with EGF was multidrug-resistant. Patients treated with EGF had no infections during the follow-up period, and there was a significant difference between the 1st and 12th week in wound infection improvement in patients treated with PRP (P = .0078).

Bacterial isolates and antimicrobial susceptibility profiles in wound swabs from the Central Polokwane NHLS, in Limpopo Province, South Africa

Bacteria are a major cause of wound infections with associated emergence of drug resistance to commonly used antimicrobials. This situation necessitates proper identification of the wound microbiota and their respective antimicrobial susceptibility profiles. A total of 88 wound swab specimens were collected and cultured by standard microbiological methods. The antibiotic susceptibility test of the bacterial isolates was performed by Kirby-Bauer disk diffusion method. Seven different species of bacteria were isolated. The most common organism isolated was Staphylococcus aureus (29%) followed by Staphylococcus epidermidis (15%), lactose fermenting coliforms (15%), Pseudomonas species (11%), Klebsiella species (7%) as well as Eschericia coli (3%) and Streptococcus group D (3%). Only 1% of Staphylococcus saprophyticus was isolated. All the positive samples were monomicrobial. Fourteen (14) samples showed no growth. The majority of the isolates were resistant to almost all the antimicrobials tested. Streptococcus group D was sensitive to mupirocin and oxacillin while Eschericia coli exhibited sensitivity for colistin sulphate and gentamicin. A high rate of multiple antibiotic resistant isolates was observed in both gram-positive and -negative bacteria. The results are presumptive of the likelihood of a changing resistant profile among the specimen tested. That might be attributable to various factors and warrants further investigation.

Metabolic modelling of chronic wound microbiota predicts mutualistic interactions that drive community composition.

To identify putative mutualistic interactions driving community composition in polymicrobial chronic wound infections using metabolic modelling. We developed a 12 species metabolic model that covered 74% of 16S rDNA pyrosequencing reads of dominant genera from 2963 chronic wound patients. The community model was used to predict species abundances averaged across this large patient population. We found that substantially improved predictions were obtained when the model was constrained with genera prevalence data and predicted abundances were averaged over 5000 ensemble simulations with community participants randomly determined according to the experimentally determined prevalences. Staphylococcus and Pseudomonas were predicted to exhibit a strong mutualistic relationship that resulted in community growth rate and diversity simultaneously increasing, suggesting that these two common chronic wound pathogens establish dominance by cooperating with less harmful commensal species. In communities lacking one or both dominant pathogens, other mutualistic relationship including Staphylococcus/Acinetobacter, Pseudomonas/Serratia and Streptococcus/Enterococcus were predicted consistent with published experimental data. Mutualistic interactions were predicted to be driven by crossfeeding of organic acids, alcohols and amino acids that could potentially be disrupted to slow chronic wound disease progression. Approximately 2% of the US population suffers from nonhealing chronic wounds infected by a combination of commensal and pathogenic bacteria. These polymicrobial infections are often resilient to antibiotic treatment due to the nutrient-rich wound environment and species interactions that promote community stability and robustness. The simulation results from this study were used to identify putative mutualistic interactions between bacteria that could be targeted to enhance treatment efficacy.