Virulence potential of Staphylococcus aureus strains isolated from diabetic foot ulcers: a new paradigm.
ABSTRACT: OBJECTIVE:The purpose of this study was to assess the virulence potential of Staphylococcus aureus strains isolated from diabetic foot ulcers and to discriminate noninfected from infected ulcers. RESEARCH DESIGN AND METHODS:Diabetic patients hospitalized in a diabetic foot department with a foot ulcer were prospectively enrolled if they had been free of antibiotic treatment over the previous 6 months. At admission, ulcers were classified as infected or noninfected on the basis of clinical examination, according to the International Working Group on the Diabetic Foot system. Only patients carrying S. aureus as the sole pathogen were included. In individuals with a grade 1 ulcer, a second bacterial specimen was obtained 1 month later. Using virulence genotyping markers, clonality tools, and an in vivo Caenorhabditis elegans model, we correlated the virulence of 132 S. aureus strains with grade, time of collection, and ulcer outcome. RESULTS:Among virulence genes, the most relevant combination derived from the logistic regression was the association of cap8, sea, sei, lukE, and hlgv (area under the curve 0.958). These markers were useful to distinguish noninfected (grade 1) from infected (grades 2-4) ulcers and to predict wound status at the follow-up. With use of the nematode model, S. aureus strains isolated from grade 1 ulcers were found to be significantly less virulent than strains from ulcers at or above grade 2 (P < 0.001). CONCLUSIONS:This study highlights the coexistence of two S. aureus populations on diabetic foot ulcers. A combination of five genes that may help distinguish colonized grade 1 from infected grade >or=2 wounds, predict ulcer outcome, and contribute to more appropriate use of antibiotics was discovered.
Project description:Infection of foot ulcers is a common, often severe and costly complication in diabetes. Diabetic foot infections (DFI) are mainly polymicrobial, and Staphylococcus aureus is the most frequent pathogen isolated. The numerous virulence factors and toxins produced by S. aureus during an infection are well characterized. However, some particular features could be observed in DFI. The aim of this review is to describe the role of S. aureus in DFI and the implication of its toxins in the establishment of the infection. Studies on this issue have helped to distinguish two S. aureus populations in DFI: toxinogenic S. aureus strains (harboring exfoliatin-, EDIN-, PVL- or TSST-encoding genes) and non-toxinogenic strains. Toxinogenic strains are often present in infections with a more severe grade and systemic impact, whereas non-toxinogenic strains seem to remain localized in deep structures and bone involving diabetic foot osteomyelitis. Testing the virulence profile of bacteria seems to be a promising way to predict the behavior of S. aureus in the chronic wounds.
Project description:Only 30 percent of chronic diabetic foot ulcers heal after 20 weeks of standard treatment. Pirfenidone is a drug with biological, anti-inflammatory, and antifibrotic effects. The aim of this study was to evaluate the effect of topical pirfenidone added to conventional treatment in noninfected chronic diabetic foot ulcers. This was a randomized crossover study. Group 1 received topical pirfenidone plus conventional treatment for 8 weeks; after this period, they were switched to receive conventional treatment only for 8 more weeks. In group 2, the order of the treatments was the opposite. The end points were complete ulcer healing and size reduction. Final data were obtained from 35 ulcers in 24 patients. Fifty-two percent of ulcers treated with pirfenidone healed before 8 weeks versus 14.3% treated with conventional treatment only (P = 0.025). Between 8 and 16 weeks, 30.8% ulcers that received pirfenidone healed versus 0% with conventional treatment (P = 0.081). By week 8, the reduction in ulcer size was 100% [73-100] with pirfenidone versus 57.5% with conventional treatment [28.9-74] (P = 0.011). By week 16, the reduction was 93% [42.7-100] with pirfenidone and 21.8% [8-77.5] with conventional treatment (P = 0.050). The addition of topical pirfenidone to conventional treatment significantly improves the healing of chronic diabetic noninfected foot ulcers.
Project description:Deciding if a diabetic foot ulcer is infected in a community setting is challenging without validated point-of-care tests. Four inflammatory biomarkers were investigated to develop a composite algorithm for mildly infected diabetic foot ulcers: venous white cell count, C-reactive protein (CRP) and procalcitonin, and a novel wound exudate calprotectin assay. Calprotectin is a marker of neutrophilic inflammation.In a prospective study, people with uninfected or mildly infected diabetic foot ulcers who had not received oral antibiotics in the preceding 2 weeks were recruited from community podiatry clinics for measurement of inflammatory biomarkers. Antibiotic prescribing decisions were based on clinicians' baseline assessments and participants were reviewed 1 week later; ulcer infection was defined by clinicians' overall impression from their two assessments.Some 363 potential participants were screened, of whom 67 were recruited, 29 with mildly infected diabetic foot ulcers and 38 with no infection. One participant withdrew early in each group. Ulcer area was 1.32 cm2 [interquartile range (IQR) 0.32-3.61 cm2 ] in infected ulcers and 0.22 cm2 (IQR 0.09-1.46 cm2 ) in uninfected ulcers. Baseline CRP for mild infection was 9.00 mg/ml and 6.00 mg/ml for uninfected ulcers; most procalcitonin levels were undetectable. Median calprotectin level in infected diabetic foot ulcers was 1437 ng/ml and 879 ng/ml in uninfected diabetic foot ulcers. Area under the receiver operating characteristic curve for a composite algorithm incorporating calprotectin, CRP, white cell count and ulcer area was 0.68 (95% confidence intervals 0.52-0.82), sensitivity 0.64, specificity 0.81.A composite algorithm including CRP, calprotectin, white cell count and ulcer area may help to distinguish uninfected from mildly infected diabetic foot ulcers. Venous procalcitonin is unhelpful for mild diabetic foot ulcer infection.
Project description:This randomized, double-blind, placebo-controlled Phase 2 clinical trial explored NorLeu(3)-A(1-7) (DSC127) safety and healing efficacy in diabetic foot ulcers. Patients with chronic, noninfected, neuropathic, or neuroischemic plantar Wagner Grade 1 or 2 foot ulcers (n = 172) were screened for nonhealing. Subjects were randomized to receive 4 weeks' once-daily topical treatment with 0.03% DSC127 (n = 26), 0.01% DSC127 (n = 27), or Placebo (n = 24), followed by 20 weeks' standard of care. DSC127 was assessed for safety (including laboratory values and adverse events), primary efficacy (% ulcers completely epithelialized at Week 12), and durability of effect. Baseline, demography, and safety parameters were compared between intent-to-treat groups and were comparable. Dose-response curves for DSC127 effect on % area reduction from baseline at Week 12 (40% placebo; 67% 0.01% DSC127; 80% 0.03% DSC127) and 24 (23% placebo; 53% 0.01% DSC127; 95% 0.03% DSC127) followed a log-linear pattern for both intent-to-treat and per-protocol populations. Covariate analysis compared reduction in ulcer area, depth, and volume from baseline; reductions in the 0.03% DSC127 group were greater at Weeks 12 and 24. Placebo-treated ulcers healed in a median 22 weeks vs. 8.5 weeks for 0.03%DSC127 (p = 0.04). This study provides preliminary evidence that DSC127 is safe and effective in accelerating the healing of diabetic foot ulcers.
Project description:To determine clinical outcomes and explore prognostic factors related to ulcer healing in people with a clinically infected diabetic foot ulcer.This multicentre, prospective, observational study reviewed participants' data at 12 months after culture of a diabetic foot ulcer requiring antibiotic therapy. From participants' notes, we obtained information on the incidence of wound healing, ulcer recurrence, lower extremity amputation, lower extremity revascularization and death. We estimated the cumulative incidence of healing at 6 and 12 months, adjusted for lower extremity amputation and death using a competing risk analysis, and explored the relationship between baseline factors and healing incidence.In the first year after culture of the index ulcer, 45/299 participants (15.1%) had died. The ulcer had healed in 136 participants (45.5%), but recurred in 13 (9.6%). An ipsilateral lower extremity amputation was recorded in 52 (17.4%) and revascularization surgery in 18 participants (6.0%). Participants with an ulcer present for ~2 months or more had a lower incidence of healing (hazard ratio 0.55, 95% CI 0.39 to 0.77), as did those with a PEDIS (perfusion, extent, depth, infection, sensation) perfusion grade of ?2 (hazard ratio 0.37, 95% CI 0.25 to 0.55). Participants with a single ulcer on their index foot had a higher incidence of healing than those with multiple ulcers (hazard ratio 1.90, 95% CI 1.18 to 3.06).Clinical outcomes at 12 months for people with an infected diabetic foot ulcer are generally poor. Our data confirm the adverse prognostic effect of limb ischaemia, longer ulcer duration and the presence of multiple ulcers.
Project description:Social bacterial interactions are considered essential in numerous infectious diseases, particularly in wounds. Foot ulcers are a common complication in diabetic patients and these ulcers become frequently infected. This infection is usually polymicrobial promoting cell-to-cell communications. <i>Staphylococcus aureus</i> is the most prevalent pathogen isolated. Its association with <i>Helcococcus kunzii</i>, commensal Gram-positive cocci, is frequently described. The aim of this study was to assess the impact of co-infection on virulence of both <i>H. kunzii</i> and <i>S. aureus</i> strains in a <i>Caenorhabditis elegans</i> model. To study the host response, qRT-PCRs targeting host defense genes were performed. We observed that <i>H. kunzii</i> strains harbored a very low (LT50: 5.7 days ± 0.4) or an absence of virulence (LT50: 6.9 days ± 0.5). In contrast, <i>S. aureus</i> strains (LT50: 2.9 days ± 0.4) were significantly more virulent than all <i>H. kunzii</i> (<i>P</i> < 0.001). When <i>H. kunzii</i> and <i>S. aureus</i> strains were associated, <i>H. kunzii</i> significantly reduced the virulence of the <i>S. aureus</i> strain in nematodes (LT50 between 4.4 and 5.2 days; <i>P</i> < 0.001). To evaluate the impact of these strains on host response, transcriptomic analysis showed that the ingestion of <i>S. aureus</i> led to a strong induction of defense genes (<i>lys-5, sodh-1</i>, and <i>cyp-37B1</i>) while <i>H. kunzii</i> did not. No statistical difference of host response genes expression was observed when <i>C. elegans</i> were infected with either <i>S. aureus</i> alone or with <i>S. aureus</i> + <i>H. kunzii</i>. Moreover, two well-characterized virulence factors (<i>hla</i> and <i>agr</i>) present in <i>S. aureus</i> were down-regulated when <i>S. aureus</i> were co-infected with <i>H. kunzii</i>. This study showed that <i>H. kunzii</i> decreased the virulence of <i>S. aureus</i> without modifying directly the host defense response. Factor(s) produced by this bacterium modulating the staphylococci virulence must be investigated.
Project description:Objectives:This study aimed to assess the overall health-related quality of life in type 2 diabetes mellitus patients with diabetic foot disease compared to diabetic patients without diabetic foot and to identify the clinical utility of this assessment. Methods:A total of 250 consecutive patients with type 2 diabetes mellitus (100/150 with/without diabetic foot, respectively) were interviewed. The questionnaires of the 36-item short-form survey and region-specific foot and ankle ability measure were applied. Wagner-Meggitt wound classification was used for foot-ulcer evaluation. Follow-up of patients for 3-6?weeks was done to identify the potential clinical short outcomes of diabetic foot ulcers. Results:Type 2 diabetes mellitus patients with diabetic foot exhibited poor mental and physical health consequences. Females had more prevalence of forefoot lesions, larger ulcer size, advanced Wagner grade, and higher frequency of unhealed ulcers. Receiver operating characteristic curve analysis demonstrated high value of foot and ankle ability measure and 36-item short-form questionnaires to discriminate type 2 diabetes mellitus patients with and without diabetic foot at cutoff values of 66 and 49.6, respectively. Foot and ankle ability measure questionnaire also showed high performance for differentiating the clinical outcome of foot ulcer. Total foot and ankle ability measure subscale score above the cutoff value of 65.5 could discriminate patients with complete healing and unhealed ulcer lesions at a high sensitivity and specificity. Conclusion:The current findings confirm the impact of diabetic foot disease on type 2 diabetes mellitus overall health-related quality of life reflected in 36-item short-form questionnaire and foot and ankle ability measure questionnaire which showed high discriminative values for type 2 diabetes mellitus patient sub-grouping. Their application in routine clinical health assessment with continuous medical education programs is highly recommended to achieve a better health-related quality of life.
Project description:Diabetic foot ulcers are frequently related to elevated pressure under a bony prominence. Conservative treatment includes offloading with orthopaedic shoes and custom made orthotics or plaster casts. While casting in plaster is usually effective in achieving primary closure of foot ulcers, recurrence rates are high. Minimally invasive surgical offloading that includes correction of foot deformities has good short and long term results. The surgery alleviates the pressure under the bony prominence, thus enabling prompt ulcer healing, negating the patient's dependence on expensive shoes and orthotics, with a lower chance of recurrence. The purpose of this protocol is to compare offloading surgery (percutaneous flexor tenotomy, mini-invasive floating metatarsal osteotomy or Keller arthroplasty) to non-surgical treatment for patients with diabetic foot ulcers in a semi-crossover designed RCT.One hundred patients with diabetic neuropathy related foot ulcers (tip of toe ulcers, ulcers under metatarsal heads and ulcers under the hallux interphalangeal joint) will be randomized (2:3) to a surgical offloading procedure or best available non-surgical treatment. Group 1 (surgery) will have surgery within 1 week. Group 2 (controls) will be prescribed an offloading cast applied for up to 12 weeks (based on clinical considerations). Following successful offloading treatment (ulcer closure with complete epithelization) patients will be prescribed orthopaedic shoes and custom made orthotics. If offloading by cast for at least 6 weeks fails, or the ulcer recurs, patients will be offered surgical offloading. Follow-up will take place till 2 years following randomization. Outcome criteria will be time to healing of the primary ulcer (complete epithelization), time to healing of surgical wound, recurrence of ulcer, time to recurrence and complications.The high recurrence rate of foot ulcers and their dire consequences justify attempts to find better solutions than the non-surgical options available at present. To promote surgery, RCT level evidence of efficacy is necessary.Israel MOH_2017-08-10_000719. NIH: NCT03414216.
Project description:OBJECTIVE:To evaluate the efficacy of a removable cast walker compared with that of a nonremovable fiberglass off-bearing cast in the treatment of diabetic plantar foot ulcer. RESEARCH DESIGN AND METHODS:Forty-five adult diabetic patients with nonischemic, noninfected neuropathic plantar ulcer were randomly assigned for treatment with a nonremovable fiberglass off-bearing cast (total contact cast [TCC] group) or walker cast (Stabil-D group). Treatment duration was 90 days. Percent reduction in ulcer surface area and total healing rates were evaluated after treatment. RESULTS:A total of 48 patients were screened; however, 2 patients in the TCC group and 1 patient in the Stabil-D group did not complete the study and were considered dropouts. There were no significant differences in demographic and clinic characteristics of the 45 patients completing the study. Ulcer surface decreased from 1.41 to 0.21 cm(2) (P < 0.001) in the TCC group and from 2.18 to 0.45 cm(2) (P < 0.001) in the Stabil-D group, with no significant differences between groups (P = 0.722). Seventeen patients (73.9%) in the TCC group and 16 patients (72.7%) in the Stabil-D group achieved healing (P = 0.794). Average healing time was 35.3 +/- 3.1 and 39.7 +/- 4.2 days in the TCC and Stabil-D group, respectively (P = 0.708). CONCLUSIONS:The Stabil-D cast walker, although removable, was equivalent in efficacy to the TCC in terms of ulcer size reduction and total healing rate. The easier use of Stabil-D may help increase the use of off-loading devices in the management of plantar neuropathic diabetic foot ulcers.
Project description:Aim:To describe differences in healing time of diabetic foot ulcers for patients treated at the Copenhagen Wound Healing Center, Bispebjerg Hospital, between the years 1999/2000 and 2011/2012. The Center is highly specialized and receives diabetes patients with hard-to-heal foot ulcers. A further aim is to attempt to find predictors of healing time of diabetic foot ulcers. Methods:A retrospective descriptive study of records from patients with diabetic foot ulcer treated at the Copenhagen Wound Healing Center in 1999, 2000, 2011, or 2012. Follow-up data was collected until the 3rd of August 2018. Results:Median time (range) to healing was 6 (61.3) months in 1999/2000 and 6.6 (67.8) in 2011/2012 (p = 0.2). About 33% of ulcers were healed, 17% were minor or major amputated, and 1.5% were dead within one year in 1999/2000, whereas 30% of ulcers were healed (p = 0.6), 14% were amputated (p = 0.2), and 12.8% were dead within one year in 2011/2012 (p < 0.001). The single factor found significantly associated with longer ulcer duration was infection. Related to shorter ulcer duration were toe localization of the ulcer and good glycemic control. Conclusion:The median time to healing of a diabetic foot ulcer was long, around 6 months and with a high recurrence rate in 1999/2000 as well as in 2011/2012. Some factors were found to be significantly related to healing time, and intervention addressing these may improve the time to heal, although such interpretations must be taken with precaution from the present study and should be proven in randomized prospective intervention trials.