Identification of Microorganism in Infected Wounds by Positively Charged Selective Sensor Array and Deep Learning Algorithm.

Microorganism are ubiquitous and intimately connected with human health and disease management. The accurate and fast identification of pathogenic microorganisms is especially important for diagnosing infections. Herein, three tetraphenylethylene derivatives (S-TDs: TBN, TPN, and TPI) featuring different cationic groups, charge numbers, emission wavelengths, and hydrophobicities were successfully synthesized. Benefiting from distinct cell wall binding properties, S-TDs were collectively utilized to create a sensor array capable of imaging various microorganisms through their characteristic fluorescent signatures. Furthermore, the interaction mechanism between S-TDs and different microorganisms was explored by calculating the binding energy between S-TDs and cell membrane/wall constituents, including phospholipid bilayer and peptidoglycan. Using a combination of the fluorescence sensor array and a deep learning model of residual network (ResNet), readily differentiation of Gram-negative bacteria (G-), Gram-positive bacteria (G+), fungi, and their mixtures was achieved. Specifically, by extensive training of two ResNet models with large quantities of images data from 14 kinds of microorganism stained with S-TDs, identification of microorganism was achieved at high-level accuracy: over 92.8% for both Gram species and antibiotic-resistant species, with 90.35% accuracy for the detection of mixed microorganism in infected wound. This novel method provides a rapid and accurate method for microbial classification, potentially aiding in the diagnosis and treatment of infectious diseases.

An exception-reporting approach for wound swab culture: effect on post-report antibiotic initiation.

A prior analysis suggested that wound swab culture (WSC) results were driving unnecessary antibiotic use in patients who were not already receiving treatment. As a quality-improvement initiative, our laboratory introduced an "exception-reporting" protocol on 1 March 2023, whereby typical wound pathogens susceptible to recommended empiric therapy (flucloxacillin/cefalexin) were not reported, and a comment was provided, stating no significant resistant organisms had been detected. Full results were available to clinicians on request. Cultures falling outside protocol criteria were reported in the standard fashion. This analysis sought to assess the effect of exception-reporting on post-report antibiotic initiation (PRAI). All community WSC results were matched to antibiotic dispensing records from October 2021 to December 2023. Sampling without treatment pre-report was termed "test and wait" (TaW). Following TaW, PRAI was identified if antibiotics were started within 5 days post-report. There were 1,819 and 764 WSCs received in the pre-change and post-change periods, respectively, where an initial TaW approach had been taken and an organism eligible for exception-reporting had been isolated. In the post-change period, 407 (53.3%) met the criteria and were exception-reported. PRAI occurred in 901 (49.5%) pre-change samples, compared to 102 (25.1%, P < 0.01) with exception-reporting. There was no detectable increase in hospitalization or repeat WSC collection in the 30 days following exception-reporting. Exception-reporting was associated with a markedly reduced proportion of patients being initiated on antibiotics following WSC where an organism had been isolated. The naming of organisms in reports appears to drive unnecessary antibiotic prescribing in many patients. These results require confirmation in other jurisdictions. IMPORTANCE: Wound swab culture is a high-volume test performed in clinical microbiology laboratories. In this analysis, we have shown that an alternative approach to reporting positive wound swab cultures has resulted in a large reduction in post-report antibiotic initiation, suggesting that the current standard method of reporting generates considerable unnecessary antibiotic use. If these findings are replicated elsewhere, wider adoption of this reporting would represent an opportunity for many clinical microbiology laboratories to have a significant impact on community antimicrobial stewardship.

Diagnosis and treatment of infected wounds: A multi-centre audit of current clinical practice across the UK, Ireland and Scandinavia.

AIMS AND OBJECTIVES: Surveillance of wound infection including signs of infection alongside antimicrobial usage (types, duration, frequency) can highlight knowledge gaps and inconsistencies. This manuscript aims to highlight these, identify and inform opportunities for practice improvement and to show impact of infection management practice may be having on the issue of antimicrobial resistance. BACKGROUND: Infected wounds pose challenges to healthcare professionals. Balancing risk of wound deterioration and progression to systemic infection with appropriate use of antimicrobials is necessary to minimise development of resistance. METHODS: Analysis consisted of a practice survey of 9661 wounds across 70 community sites over a period of one week. Data were collected from projects between 2017 and 2020. The form was available to providers within the UK, Ireland, Norway, Denmark, Sweden and Finland. EQUATOR research guidelines were followed; STROBE checklist for observational research reporting was completed. RESULTS: Infection rates of 8.9% were reported from wounds assessed. These data indicate inconsistencies with diagnosis across practice with non-specialists more likely to be unsure of wound infection. Greater confidence in infection identification was observed as number of signs increased. Inconsistencies were also observed in appropriate treatment; antimicrobials were used in 35% of wounds considered not infected and not used in 41% of wounds that were identified as infected. CONCLUSIONS: This investigation of infection management practice of over 9000 wounds provides an insight into diagnosis and treatment of infection. Inconsistencies in diagnosis and treatment of wound infections reported highlight the need for increased education, awareness of diagnosis and treatment of infection. RELEVANCE TO CLINICAL PRACTICE: Variability in management of infected wounds highlights opportunities to aid more effective diagnosis and treatment of infected wounds. Incorporation of support tools or evidence-based pathways into practice may enhance confidence in management of local infection, balanced with appropriate use, potentially minimising resistance and improving outcomes.

Loop-Mediated Isothermal Amplification of DNA (LAMP) as an Alternative Method for Determining Bacteria in Wound Infections.

The increasing number of patients with chronic wounds requires the development of quick and accurate diagnostics methods. One of the key and challenging aspects of treating ulcers is to control wound infection. Early detection of infection is essential for the application of suitable treatment methods, such as systemic antibiotics or other antimicrobial agents. Clinically, the most frequently used method for detecting microorganisms in wounds is through a swab and culture on appropriate media. This test has major limitations, such as the long bacterial growth time and the selectivity of bacterial growth. This article presents an overview of molecular methods for detecting bacteria in wounds, including real-time polymerase chain reaction (rtPCR), quantitative polymerase chain reaction (qPCR), genotyping, next-generation sequencing (NGS), and loop-mediated isothermal amplification (LAMP). We focus on the LAMP method, which has not yet been widely used to detect bacteria in wounds, but it is an interesting alternative to conventional detection methods. LAMP does not require additional complicated equipment and provides the fastest detection time for microorganisms (approx. 30 min reaction). It also allows the use of many pairs of primers in one reaction and determination of up to 15 organisms in one sample. Isothermal amplification of DNA is currently the easiest and most economical method for microbial detection in wound infection. Direct visualization of the reaction with dyes, along with omitting DNA isolation, has increased the potential use of this method.

[Diagnostics and treatment of local wound infections]. / Diagnostik und Therapie lokaler Wundinfektionen.

Local wound infections are a multidisciplinary challenge which should be diagnosed as early as possible and adequately treated. In addition to a stagnation of wound healing, it is in particular the threat of development into systemic infections and even sepsis that represent feared, potentially life-threatening complications. This topic has a particularly high and multidisciplinary significance in the treatment of patients with chronic wounds. Until now, there were no generally accepted criteria for the diagnostics. The newly developed and validated TILI score, as a supplement to vital signs and serological values, enables rapid objectification of local wound infections. In addition, the W.A.R. score can be used to identify patients with an increased risk of infections. With these easy to use tools, the indications for antiseptic wound treatment can be assessed individually, quickly and without problems. For many patients with chronic wounds, polihexanide is then the wound antiseptic of first choice. However, the indications for wound antiseptics should be critically reviewed after a treatment duration of 14 days at the latest.

Point-of-care fluorescence imaging reveals extent of bacterial load in diabetic foot ulcers.

Elevated levels of bacteria, including biofilm, increase the risk of chronic wound infection and inhibit healing. Addressing asymptomatic high bacterial loads is challenged by a lack of clinical terminology and diagnostic tools. This post-hoc multicenter clinical trial analysis of 138 diabetic foot ulcers investigates fluorescence (FL)-imaging role in detecting biofilm-encased and planktonic bacteria in wounds at high loads. The sensitivity and specificity of clinical assessment and FL-imaging were compared across bacterial loads of concern (104 -109 CFU/g). Quantitative tissue culture confirmed the total loads. Bacterial presence was confirmed in 131/138 ulcers. Of these, 93.9% had loads >104 CFU/g. In those wounds, symptoms of infection were largely absent and did not correlate with, or increase proportionately with, bacterial loads at any threshold. FL-imaging increased sensitivity for the detection of bacteria across loads 104 -109 (P < .0001), peaking at 92.6% for >108 CFU/g. Imaging further showed that 84.2% of ulcers contained high loads in the periwound region. New terminology, chronic inhibitory bacterial load (CIBL), describes frequently asymptomatic, high bacterial loads in diabetic ulcers and periwound tissues, which require clinical intervention to prevent sequelae of infection. We anticipate this will spark a paradigm shift in assessment and management, enabling earlier intervention along the bacterial-infection continuum and supporting improved wound outcomes.

Challenges in the diagnosis and management of wound infection.

Human epithelia are constantly exposed to microorganisms present in the environment or residing as part of commensal flora. Despite this exposure, infections involving the skin and subcutaneous tissue in healthy individuals are, fortunately, quite rare. Many of the wounds that afflict the human body occur in individuals of ill health and/or where the mechanism of wounding is impeded by host immunological, physiological or regenerative dysfunction. The interplay between microorganisms and host immunity is complex and remains ill defined; however, the interpretation of downstream manifestations of the host response to invading microorganisms is still based largely on the clinical signs and symptoms of an active infectious process. In this review article we will provide a brief overview of the current challenges clinicians face in diagnosing wound infections, how chronic infections caused by biofilms are a major challenge, and how there have been minimal advancements in developing new diagnostics or therapeutics in the identification and management of wound infections.

Detecting bacterial infections in wounds: a review of biosensors and wearable sensors in comparison with conventional laboratory methods.

Bacterial infection is a common impediment towards wound healing. Detecting bacterial infections is important to promote wound healing and curb chronic non-healing wounds. In this review, we firstly discuss bacterial communities, including aerobic and anaerobic bacteria in various types of wounds. Following the discussion of wound sampling methods (swab, biopsy) for different wounds, we then discuss laboratory based conventional methods (bacteria cultures, Gram staining, analytical profile index systems, polymerase chain reaction, and gas chromatography coupled with mass spectrometry), focusing on their recent improvement. After that we discussed the contemporary biosensor methods, including e-Nose, electrochemical sensors, surface enhanced Raman spectroscopy, and nucleic acid lateral flow immunoassay. Biosensors embedded into wound dressing, termed wearable sensors or smart wound dressing, are also discussed for their ability of enabling bacteria detection directly from wound sites without the need for obtaining swab/biopsy samples. We have compared all the detection methods for their performance according to their respective targets (either bacteria cells or volatile/non-volatile metabolites); after that we evaluate the suitability of various methods in providing timely and accurate diagnostic results towards real-time, point-of-care testing of bacterial infections.

Real-time detection of volatile metabolites enabling species-level discrimination of bacterial biofilms associated with wound infection.

AIMS: The main aim of this study was to investigate the real-time detection of volatile metabolites for the species-level discrimination of pathogens associated with clinically relevant wound infection, when grown in a collagen wound biofilm model. METHODS AND RESULTS: This work shows that Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pyogenes produce a multitude of volatile compounds when grown as biofilms in a collagen-based biofilm model. The real-time detection of these complex volatile profiles using selected ion flow tube mass spectrometry and the use of multivariate statistical analysis on the resulting data can be used to successfully differentiate between the pathogens studied. CONCLUSIONS: The range of bacterial volatile compounds detected between the species studied vary and are distinct. Discrimination between bacterial species using real-time detection of volatile metabolites and multivariate statistical analysis was successfully demonstrated. SIGNIFICANCE AND IMPACT OF THE STUDY: Development of rapid point-of-care diagnostics for wound infection would improve diagnosis and patient care. Such technological approaches would also facilitate the appropriate use of antimicrobials, minimizing the emergence of antimicrobial resistance. This study further develops the use of volatile metabolite detection as a new diagnostic approach for wound infection.

Establishing a consensus on wound infection definitions.

OBJECTIVES: The aim of this study was to establish an international, interorganisational consensus on wound infection terminology. METHODS: This project consisted of definition scoping and a Delphi process to produce a consensus glossary for 18 wound infection terms. Recent guidelines/consensus documents were reviewed to identify 2-4 definitions for each term. An online consensus process was undertaken using the RAND Appropriateness Method, a consensus method for panels to reach agreement. International wound organisations nominated experts to participate, from whom 21 participants were selected to represent different organisations, geographic regions and disciplines. In the first consensus round, each term was presented alongside 2-3 definitions and participants nominated their preferred definition, with the majority vote used to select a baseline definition. The consensus process then proceeded, with participants using a 9-point Likert scale to score their level of agreement or disagreement with the definition for each term. Participants also provided a justification outlining the reason behind their rating. At the end of each round, an index was calculated to provide a quantitative evaluation indicating whether agreement or disagreement had been reached. RESULTS: Reasoning statements were summarised and the definitions were adjusted to incorporate concepts identified by participants. The adjusted definition was presented in the next consensus round, together with the reasoning statements. Terms for which a final definition was not achieved in three consensus rounds were finalised with preferential voting using 2-3 definitions that had reached consensus. PROJECT PROGRESS AND SIGNIFICANCE: The project generated a glossary of wound infection terms, endorsed through participation of 15 international organisations, for dissemination of guidelines and clinical decision-making/teaching tools.

Bacterial protease activity: a prognostic biomarker of early wound infection.

OBJECTIVE: High bacterial burden is one of several reasons that wounds fail to heal. At present, clinicians rely primarily on clinical signs and symptoms (CSS) to diagnose infection in hard-to-heal wounds; however, studies have demonstrated that CSS can be unreliable. This is especially true in the early stages of bacterial infection. Bacteria release proteases, virulence factors that promote invasive infection. This clinical trial evaluated the use of bacterial protease activity (BPA) as a biomarker to detect whether a wound was in the period of pathogenicity, prior to overt clinical signs. METHOD: Participants were drawn from six US wound centres and had their wounds assessed clinically for infection. In addition, wound fluid swabs were collected and analysed for BPA, inflammatory cytokines (interleukin-1ß (IL-1ß), interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α)), and cultured for quantitative microbiology. RESULTS: A total of 366 patients were recruited. The median BPA level increased with the increasing number of signs of infection. The majority of wounds tested positive for elevated BPA prior to exhibiting at least three CSS of infection, the level at which the criteria for infection are met. BPA tended to increase with the bioburden (colony forming unit (CFU)/ml) although some wounds with high bioburden were negative for BPA, and others with low bioburden were positive for BPA. The mean levels of IL-1ß and TNF-α were significantly higher in BPA-positive wounds (p<0.0001 and p=0.0002, respectively). CONCLUSION: The results of this clinical trial suggest that measuring BPA can lead to the early detection of pathogenic bacteria in the wound that impede wound healing and may progress to invasive infection. In a large percentage of cases, BPA detected virulent bacteria in the absence of CSS of infection. As a biomarker, BPA has an advantage over measuring bacterial load-hard-to-heal wounds are often colonised with non-pathogenic bacteria that do not inhibit wound healing and, conversely, a low number of highly virulent species could disrupt the healing process.

Rapid Colorimetric Detection of Wound Infection with a Fluidic Paper Device.

Current procedures for the assessment of chronic wound infection are time-consuming and require complex instruments and trained personnel. The incidence of chronic wounds worldwide, and the associated economic burden, urge for simple and cheap point-of-care testing (PoCT) devices for fast on-site diagnosis to enable appropriate early treatment. The enzyme myeloperoxidase (MPO), whose activity in infected wounds is about ten times higher than in non-infected wounds, appears to be a suitable biomarker for wound infection diagnosis. Herein, we develop a single-component foldable paper-based device for the detection of MPO in wound fluids. The analyte detection is achieved in two steps: (i) selective immunocapture of MPO, and (ii) reaction of a specific dye with the captured MPO, yielding a purple color with increasing intensity as a function of the MPO activity in infected wounds in the range of 20-85 U/mL. Ex vivo experiments with wound fluids validated the analytic efficiency of the paper-based device, and the results strongly correlate with a spectrophotometric assay.

A non-contact device for fast screening of wound infections.

Screening for wound infection relies on the expertise of the provider. Clinical diagnosis of infections based on wound swab/biopsy results often takes a few days and may not assess the full wound. There is a need for a non-invasive tool that can quickly and accurately diagnose wound infection. Leukocyte esterase strips are used to identify various infectious diseases. However, it is not clear whether infected wounds also have elevated leukocyte esterase activities as compared with non-infected wounds. To achieve the objective, a device was developed to detect elevated leukocyte esterase activities in wounds by measuring wound exudates adsorbed onto wound dressings in 3 minutes. The efficacy of the device in assessing leukocyte esterase activities across various chronic wounds was tested. Such measurements were unaffected by the type of underlying wound dressing. By correlating the device outputs with clinical adjudication of infection, we found that this device had high positive predictive values for diagnosing wound infection in a wide variety of chronic wounds. In addition, a positive device output increases the probability of detecting infected wounds, while the negative device output reduces the probability of detecting infected wounds. This rapid non-contact and disposable diagnostic tool may serve as a rapid and accurate indication of infection in the chronic wound.

Bacterial chatter in chronic wound infections.

One of the hallmark characteristics of chronic diabetic wounds is the presence of biofilm-forming bacteria. Bacteria encapsulated in a biofilm may coexist as a polymicrobial community and communicate with each other through a phenomenon termed quorum sensing (QS). Here, we describe the QS circuits of bacterial species commonly found in chronic diabetic wounds. QS relies on diffusion of signaling molecules and the local concentration changes of these molecules that bacteria experience in wounds. These biochemical signaling pathways play a role not only in biofilm formation and virulence but also in wound healing. They are, therefore, key to understanding the distinctive nature of these infections. While several in vivo and in vitro models exist to study QS in wounds, there has been limited progress in understanding the interplay between QS molecules and host factors that contribute to wound healing. Lastly, we examine the potential of targeting QS for both diagnosis and therapeutic intervention purposes.

Concurrent validity of biofilm detection by wound blotting on hard-to-heal wounds.

OBJECTIVE: Wound biofilms delay healing of hard-to-heal wounds. Convenient biofilm identification tools for clinical settings are currently not available, hindering biofilm-based wound management. Wound blotting with biofilm staining is a potential tool for biofilm detection, owing to its convenience. Although predictive validity of wound blotting has been established, it is necessary to confirm its concurrent validity. Furthermore, current staining systems employing ruthenium red have some disadvantages for clinical use. This study aimed to evaluate the usability of alcian blue as a substitute for ruthenium red. METHOD: Both in vitro and in vivo clinical samples were used to investigate validity and usability. RESULTS: The in vitro study showed that proteins and extracellular DNA in biofilms did not affect staining ability of ruthenium red and alcian blue in the detection of biofilms. In the in vivo study, using a wound biofilm model with Pseudomonas aeruginosa, the staining sensitivity of ruthenium red was 88.9% and 100% for alcian blue, with correlation coefficients of signal intensities with native polyacrylamide gel electrophoresis (PAGE) of r=0.67 (p=0.035) and r=0.67 (p=0.036) for ruthenium red and alcian blue, respectively. Results from clinical samples were r=0.75 (p=0.001) for ruthenium red and r=0.77 (p<0.001) for alcian blue. The sensitivities of wound blotting staining by ruthenium red and alcian blue were very high and had a good correlation with native PAGE analysis. CONCLUSION: Because the alcian blue procedure is more convenient than the ruthenium red procedure, wound blotting with alcian blue staining would be a promising tool to guide clinicians in delivering biofilm-based wound management.

A Comprehensive Review of the Pathogenesis, Diagnosis, and Management of Diabetic Foot Infections.

GENERAL PURPOSE: To review an approach to diabetic foot infections (DFIs), including acute osteomyelitis, while also discussing current practices and the challenges in diagnosis and management. TARGET AUDIENCE: This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care. LEARNING OBJECTIVES/OUTCOMES: After participating in this educational activity, the participant will1. Identify the risk factors for developing DFIs.2. Outline diagnostic techniques for assessing DFIs.3. Select the assessment techniques that support a diagnosis of osteomyelitis.4. Choose the appropriate pharmacologic and nonpharmacologic treatment options for patients who have DFIs. ABSTRACT: Diabetic foot ulcers result from a combination of peripheral neuropathy, vascular compromise, and repetitive trauma. Approximately 50% of individuals with diabetic foot ulcers will develop a diabetic foot infection (DFI), and 20% of individuals with a DFI will develop osteomyelitis. Herein, the authors review an approach to DFIs including acute osteomyelitis and discuss current practices and challenges in diagnosis and management.The diagnosis of a skin and soft tissue DFI is based on clinical criteria. A bone biopsy is considered the criterion standard for diagnosis of osteomyelitis; however, biopsy is not always feasible or available. Consequently, diagnosis can be made using a combination of clinical, biochemical, and radiographic findings. X-ray is the recommended imaging modality for initial evaluation; however, because of its lower relative sensitivity, advanced imaging may be used when clinical suspicion remains after negative initial testing.The microbiology of skin and soft tissue DFIs and osteomyelitis is similar. Staphylococcus aureus and other Gram-positive cocci are the most common pathogens identified. Deep cultures are preferred in both DFI and osteomyelitis to identify the etiologic pathogens implicated for targeted antimicrobial therapy. Management also requires a multidisciplinary approach. Surgical debridement in those with deep or severe infections is necessary, and surgical resection of infected bone is curative in cases of osteomyelitis. Finally, appropriate wound care is critical, and management of predisposing factors, such as peripheral neuropathy, peripheral arterial disease, tinea, and edema, aids in recovery and prevention.

Detection of bacterial fluorescence from in vivo wound biofilms using a point-of-care fluorescence imaging device.

Wound biofilms must be identified to target disruption and bacterial eradication but are challenging to detect with standard clinical assessment. This study tested whether bacterial fluorescence imaging could detect porphyrin-producing bacteria within a biofilm using well-established in vivo models. Mouse wounds were inoculated on Day 0 with planktonic bacteria (n = 39, porphyrin-producing and non-porphyrin-producing species, 107  colony forming units (CFU)/wound) or with polymicrobial biofilms (n = 16, 3 biofilms per mouse, each with 1:1:1 parts Staphylococcus aureus/Escherichia coli/Enterobacter cloacae, 107  CFU/biofilm) that were grown in vitro. Mouse wounds inoculated with biofilm underwent fluorescence imaging up to Day 4 or 5. Wounds were then excised and sent for microbiological analysis. Bacteria-matrix interaction was assessed with scanning electron microscopy (SEM) and histopathology. A total of 48 hours after inoculation with planktonic bacteria or biofilm, red fluorescence was readily detected in wounds; red fluorescence intensified up to Day 4. Red fluorescence from biofilms persisted in excised wound tissue post-wash. SEM and histopathology confirmed bacteria-matrix interaction. This pre-clinical study is the first to demonstrate the fluorescence detection of bacterial biofilm in vivo using a point-of-care wound imaging device. These findings have implications for clinicians targeting biofilm and may facilitate improved visualisation and removal of biofilms.

Staphylococcus aureus Biofilm Infection Compromises Wound Healing by Causing Deficiencies in Granulation Tissue Collagen.

OBJECTIVE: The objective of this work was to causatively link biofilm properties of bacterial infection to specific pathogenic mechanisms in wound healing. BACKGROUND: Staphylococcus aureus is one of the four most prevalent bacterial species identified in chronic wounds. Causatively linking wound pathology to biofilm properties of bacterial infection is challenging. Thus, isogenic mutant stains of S. aureus with varying degree of biofilm formation ability was studied in an established preclinical porcine model of wound biofilm infection. METHODS: Isogenic mutant strains of S. aureus with varying degree (ΔrexB > USA300 > ΔsarA) of biofilm-forming ability were used to infect full-thickness porcine cutaneous wounds. RESULTS: Compared with that of ΔsarA infection, wound biofilm burden was significantly higher in response to ΔrexB or USA300 infection. Biofilm infection caused degradation of cutaneous collagen, specifically collagen 1 (Col1), with ΔrexB being most pathogenic in that regard. Biofilm infection of the wound repressed wound-edge miR-143 causing upregulation of its downstream target gene matrix metalloproteinase-2. Pathogenic rise of collagenolytic matrix metalloproteinase-2 in biofilm-infected wound-edge tissue sharply decreased collagen 1/collagen 3 ratio compromising the biomechanical properties of the repaired skin. Tensile strength of the biofilm infected skin was compromised supporting the notion that healed wounds with a history of biofilm infection are likely to recur. CONCLUSION: This study provides maiden evidence that chronic S. aureus biofilm infection in wounds results in impaired granulation tissue collagen leading to compromised wound tissue biomechanics. Clinically, such compromise in tissue repair is likely to increase wound recidivism.

Functional ambulatory status as a potential adjunctive decision-making tool following wound, level of ischemia, and severity of foot infection assessment.

The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System has been developed to stratify amputation risk on the basis of extent of the wound, level of ischemia, and severity of foot infection (WIfI). However, there are no currently validated metrics to assess, grade, and consider functional status, especially ambulatory status, as a major consideration during limb salvage efforts. Therefore, we propose an adjunct to the current WIfI system to include the patient's ambulatory functional status after initial assessment of limb threat. We propose a functional ambulatory score divided into grade 0, ambulation outside the home with or without an assistive device; grade 1, ambulation within the home with or without an assistive device; grade 2, minimal ambulation, limbs used for transfers; and grade 3, a person who is bed-bound. Adding ambulatory function as a supplementary assessment tool can guide clinical decision making to achieve optimal future functional ambulatory outcome, a patient-centered goal as critical as limb preservation. This adjunct may aid limb preservation teams in rapid, effective communication and clinical decision making after initial WIfI assessment. It may also improve efforts toward patient-centered care and functional ambulatory outcome as a primary objective. We suggest a score of functional ambulatory status should be included in future trials of patients with chronic limb-threatening ischemia.

Short-term contemporary outcomes for staged versus primary lower limb amputation in diabetic foot disease.

BACKGROUND: Major lower extremity amputations remain among the most common procedures performed by vascular surgeons in patients with diabetes and its associated peripheral vascular disease. After major amputation, this population commonly suffers from high readmission rates, increased wound complications, and conversion to more proximal major amputations. These events impact quality in terms of cost, resources, and subjective quality of life. The aim of this study is to compare outcomes between primary lower extremity above-ankle amputations (primary amputation [PA]) and staged ankle guillotine amputations followed by interval formalization to an above-ankle amputation (staged amputation [SA]) for nonsalvageable infected diabetic foot disease. METHODS: A retrospective review of all de novo major lower extremity amputations performed by the vascular surgery service at a single institution between January 2014 and March 2017 was performed. Inclusion criteria were diabetic patients with foot gangrene who underwent a major de novo above- or below-knee amputation. Amputations for trauma, acute limb ischemia, or malignancy were excluded. Per institutional practice, SA was performed for uncontrolled infection and/or infection with uncontrolled diabetes, and PA was performed in the absence of active infection and in stable diabetes. The primary outcome measure was 30-day freedom from conversion to a higher level amputation. Secondary outcome measures were 30-day stump complications, 30-day readmissions, 30-day major adverse cardiovascular events, and 30-day mortality. RESULTS: One hundred sixteen patients met the inclusion criteria. Sixty-eight percent were male, 18% were active smokers, 30% had end-stage renal disease, and 22% had congestive heart failure. Sixty-one patients underwent SA, and 55 patients underwent PA. The two cohorts were well-matched by demographics and comorbidities. Consistent with the institutional practice, 57% of SA patients met two or more systemic inflammatory response syndrome criteria at presentation compared with 24% of PA patients (P = .0003). There were no 30-day mortalities. There was no significant difference in major adverse cardiovascular events between the groups (2% vs 4%; SA vs PA, respectively; P = .6). The average length of stay did not significantly differ between SA and PA (mean of 14 ± 8 days vs 11 ± 11 days; P = .1). SA patients had a lower rate of 30-day readmission (7% vs 27%; P = .005) and 30-day unplanned conversion to higher level amputation (2% vs 13%; P = .026) compared with PA patients. CONCLUSIONS: In the setting of infected diabetic foot disease, a staged lower extremity amputation achieves quality outcomes superior to a one-stage amputation, despite the former cohort's greater illness acuity level. SA should be considered in all diabetic patients presenting with active foot infection.