Histopathologic characteristics of bone infection complicating foot ulcers in diabetic patients

State-of-the-art update for diagnosing diabetic foot osteomyelitis: a narrative review

Recently, the International Working Group on the Diabetic Foot and the Infectious Diseases Society of America divided diabetic foot disease into diabetic foot infection (DFI) and diabetic foot osteomyelitis (DFO). DFI is usually diagnosed clinically, while numerous methods exist to diagnose DFO. In this narrative review, the authors aim to summarize the updated data on the diagnosis of DFO. An extensive literature search using "diabetic foot [MeSH]" and "osteomyelitis [MeSH]" or "diagnosis" was performed using PubMed and Google Scholar in July 2023. The possibility of DFO is based on inflammatory clinical signs, including the probe-to-bone (PTB) test. Elevated inflammatory biochemical markers, especially erythrocyte sedimentation rate, are beneficial. Distinguishing abnormal findings of plain radiographs is also a first-line approach. Moreover, sophisticated modalities, including magnetic resonance imaging and nuclear medicine imaging, are helpful if doubt remains after a first-line diagnosis. Transcutaneous bone biopsy, which does not pass through the wound, is necessary to avoid contaminating the sample. This review focuses on the current diagnostic techniques for DFOs with an emphasis on the updates. To obtain the correct therapeutic results, selecting a proper option is necessary. Based on these numerous diagnosis modalities and indications, the proper choice of diagnostic tool can have favorable treatment outcomes.

Residual osteomyelitis at the resection margin after conservative surgery is not associated with the recurrence of diabetic foot infection and may successfully be treated without postoperative antibiotic therapy

AIMS

We hypothesize that microbiology- and pathology-confirmed positive bone margins after the resection of diabetes-related foot osteomyelitis are associated with worse outcomes.

METHODS

We conducted a prospective study consisting of a cohort of 93 patients with diabetes-related foot osteomyelitis (histopathology confirmed) who underwent bone resection and where an additional bone biopsy was taken at the resection margin. The primary outcome was the recurrence of the infection.

RESULTS

Pathology-confirmed positive margins were detected in 62 cases (66.7%), microbiology-confirmed positive margins were detected in 75 cases (80.6%) and recurrence was detected in 19 patients (20.4%). Chi-squared test failed to show the presence of an association between the recurrence of the infection with pathology-confirmed positive margins (p = 0.82), with microbiology-confirmed positive margins, (p = 0.34) and with the use of postoperative antibiotics (p = 0.70). Healing in patients with pathology-confirmed positive margins was achieved in a median of 12 weeks (95% CI 9.2-18) and those with pathology-confirmed negative margins in 14.9 weeks (95% CI 10.2-21.9), Log-rank test, p = 0.74. Thirty-four patients out of 61 available for follow-up (55.7%) with pathology-confirmed positive margins were treated without postoperative antibiotics. In that group, Chi-squared test failed to show the presence of an association between the recurrence of the infection with the use of postoperative antibiotics (p = 0.47).

CONCLUSIONS

A positive margin was neither associated with the recurrence of the infection nor with the time to healing. More than half of patients with pathology-confirmed positive margins were treated without postoperative antibiotics and this approach was not associated with the recurrence of the infection.

Bacterial Diversity and Antibiotic Resistance in Patients with Diabetic Foot Osteomyelitis

This study analysed the bacterial diversity, antibiotic susceptibility, and resistance in patients with complications of diabetic foot osteomyelitis (DFO). A retrospective observational study was carried out between September 2019 and September 2022 and involved 215 outpatients with a diagnosis of DFO at a specialized diabetic foot unit. A total of 204 positive bone cultures were isolated, including 62.7% monomicrobial cultures, and 37.3% were formed with at least two microorganisms. We observed that Proteus spp., Coagulase-negative staphylococci (CoNS), Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Corynebacterium were the most frequently isolated microorganisms and accounted for more than 10% of the DFO cases. With stratification by Gram-positive (GP) and Gram-negative (GN) bacteria, we observed that 91.6% of cultures presented at least one GP bacteria species, and 50.4% presented at least one GN bacteria species. The most common GP species were CoNS (29%), S. aureus (25.8%), and Corynebacterium spp. (14%). The most frequent GN species consisted of Proteus spp. (32%), P. aeruginosa (23.3%), and E. coli (17.5%). The main antibiotics with resistance to GP-dominated infections were penicillins without β-lactamase inhibitor, and those in GN-dominated infections were sulfonamides and penicillins without β-lactamase. Significant differences were not observed in mean healing time in DFU with acute osteomyelitis (12.76 weeks (4.50;18)) compared to chronic osteomyelitis (15.31 weeks (7;18.25); p = 0.101) and when comparing cases with soft tissue infection (15.95 (6;20)) and those without such an infection (16.59 (7.25;19.75), p = 0.618). This study shows that when treatment of DFO is based on early surgical treatment, the type of DFO and the presence of soft infection are not associated with different or worse prognoses.

Pathomorphological and pathochemical characteristic of the osteomyelitis focus in patients with diabetic osteoarthropathy (Charcot foot)

BACKGROUND: Osteomyelitis in diabetic osteoarthropathy occurs in 65 % of cases, and it is the main cause of non-traumatic amputations. The choice of optimal treatment technologies should be based on understanding the pathogenetic characteristics of this disease.

AIM: To study the pathomorphological and pathochemical picture of osteomyelitic focus in patients with diabetic neuroosteoarthropathy.

MATERIALS AND METHODS: Object — 20 patients (55.3±9.33 years) with Type 2 diabetes mellitus, diabetic neuroosteoarthropathy, chronic osteomyelitis of the foot bones. The treatment consisted in surgical debridement of the purulent focus with the material collection for pathomorphological and biochemical studies, and in reposition and alignment of bone fragments with the leg and foot fixation using the Ilizarov fixator in order to form bone ankylosis of the compromised joint.

RESULTS: Subacute and acute course of chronic osteomyelitis was registered in 80 % of cases. As for the pathohistological changes in bone tissue, the following ones were the most significant: necrosis and the presence of an inflammatory infiltrate of varying severity depending on the phase of the inflammatory process. The articular cartilage structure was broken in all the cases. Activation of osteoclasts was observed in the osteomyelitis focus, especially in the subchondral zone. There was no subchondral bone plate in most cases, or only its fragments remained. Pathohistological examination of the soft tissues associated with the osteomyelitis focus indicated the presence of mirocirculatory and denervation disorders due to necrosis and hyalinosis of a significant part of microvessels against the background of compensatory hypervascularisation and chronic inflammation, narrowing and obliteration of the lumens of feeding arteries, almost complete absence of nerve elements in the tissues or their destructive changes. An increase in the activity of lytic enzymes was revealed in the interstitial environment of the tissues surrounding the osteomyelitis focus (138-fold increase in the activity of acid phosphatase, interstitial osteolytic index was 7.2-fold higher than blood serum index).

CONCLUSION: The pathomorphological signs of chronic osteomyelitis subacute and acute processing were observed in most patients. Breaking the articular cartilage structure was accompanied by invasion of vessels, inflammatory infiltrate, and by activation of osteoclasts in the subchondral zone. Destructive changes of vessels and nerves in the soft tissues associated with the osteomyelitis focus can be etiopathogenetic factors of this disease development. The technologies for stopping this process should be based on obligatory debridement of the focus with sequestrnecrectomy, with regular monitoring of the operated segment condition.

Metatranscriptome sequencing identifies Escherichia are major contributors to pathogenic functions and biofilm formation in diabetes related foot osteomyelitis

Osteomyelitis in the feet of persons with diabetes is clinically challenging and is associated with high rates of amputation. In this study RNA-sequencing was employed to explore microbial metatranscriptomes with a view to understand the relative activity and functions of the pathogen/s responsible for diabetes foot osteomyelitis (DFO). We obtained 25 intraoperative bone specimens from persons with confirmed DFO, observing that Escherichia spp. (7%), Streptomyces spp. (7%), Staphylococcus spp. (6%), Klebsiella spp. (5%) and Proteus spp. (5%) are the most active taxa on average. Data was then subset to examine functions associated with pathogenesis (virulence and toxins), biofilm formation and antimicrobial/multi-drug resistance. Analysis revealed Escherichia spp. are the most active taxa relative to pathogenic functions with K06218 (mRNA interferase relE), K03699 (membrane damaging toxin tlyC) and K03980 (putative peptidoglycan lipid II flippase murJ), K01114 (membrane damaging toxin plc) and K19168 (toxin cptA) being the most prevalent pathogenic associated transcripts. The most abundant transcripts associated with biofilm pathways included components of the biofilm EPS matrix including glycogen synthesis, cellulose synthesis, colonic acid synthesis and flagella synthesis. We further observed enrichment of a key enzyme involved in the biosynthesis of L-rhamnose (K01710 -dTDP-glucose 4,6-dehydratase rfbB, rmlB, rffG) which was present in all but four patients with DFO.

Evaluation of Adherence to the Oral Antibiotic Treatment in Patients With Diabetic Foot Infection

Introduction: The knowledge about level of adherence to oral antibiotic treatment in diabetic patients with ulcer infection could be essential as a method of evaluation/monitoring of conservative treatment. Aim: To assess the adherence to oral antibiotic treatment in outpatients with diabetic foot infection (soft tissue vs. osteomyelitis) by 8-item structured, self-reported medication adherence scale. Methods: cross-sectional study was carried out with 46 consecutive patients who had diabetic foot infection (soft tissue or bone infection) and required antibiotic oral treatment at outpatient clinical setting. Medication adherence was tested using the Spanish version of the validated eight-item self-report MMAS-8. Results: patients with diabetic ulcer infection, had well level of adherence to antibiotic medication (7   ±   1.2 vs. 7.4   ±   1.5). Patients with lower level of adherence had lower level of satisfaction with the antibiotic medication. The profile of the patients with lower level of adherence were patients with primary level of education and patient who required more help to take the medication. Conclusion: Patients with diabetic foot infection demonstrated well level of adherence to antibiotic medication, independently of type of infection (soft tissue vs. osteomyelitis) by 8-item structured, self-reported medication adherence scale.

Diagnostic Accuracy of Bone Culture Versus Biopsy in Diabetic Foot Osteomyelitis

OBJECTIVE

To compare the diagnostic accuracy of bone culture (microbiology) and biopsy (histology) in patients with acute or chronic diabetic foot osteomyelitis (DFO).

METHODS

This cross-sectional study involved patients for whom providers had a clinical suspicion of DFO. Two bone samples were taken: one for microbiologic testing and another for histologic testing. The sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio were calculated for bone culture results in relation to the probability of DFO diagnosis.

RESULTS

Fifty-two patients were included; 69% had positive bone culture results, and 90.4% had positive histology results (P = .013), and of those 90.4%, 25.5% had acute and 74.5% had chronic DFO. The sensitivity of the microbiologic bone culture result was 0.70, the specificity was 0.40, the positive predictive value was 0.92, and the negative predictive value was 0.13.

CONCLUSIONS

Histology provides more accurate diagnosis of DFO than microbiology, especially for patients with chronic DFO. These patients could be underdiagnosed because of false-negative results provided by bone culture. Providers should perform both tests to confirm the presence of DFO.

The Infected Diabetic Foot: Re-evaluating the Infectious Diseases Society of America Diabetic Foot Infection Classification

BACKGROUND

We provide evidence to revise the Infectious Diseases Society of America (IDSA) diabetic foot infection classification by adding a separate tier for osteomyelitis and evaluating if moderate and severe infection criteria improve the classification's ability to direct therapy and determine outcomes.

METHODS

We retrospectively evaluated 294 patients with moderate and severe infections. Osteomyelitis was confirmed by bone culture or histopathology. Soft tissue infection (STI) was based on negative bone culture, magnetic resonance imaging, or single-photon emission computed tomography. We stratified STI and osteomyelitis using IDSA criteria for moderate and severe infections and compared outcomes and complications.

RESULTS

Osteomyelitis patients had greater antibiotic duration (32.5 ± 46.8 vs 63.8 ± 55.1 days; P < .01), surgery frequency (55.5% vs 99.4%; P < .01), number of surgeries (2.1 ± 1.3 vs 3.3 ± 2.3; P < .01), amputations (26.3% vs 83.4%; P < .01), reinfection (38.0% vs 56.7%; P < .01), and length of stay (14.5 ± 14.9 vs 22.6 ± 19.0 days; P < .01). There were no differences in moderate and severe STI outcomes except for infection readmissions (46.2% vs 25.0%; P = .02), and acute kidney injury (31.2% vs 50.0%; P = .03). There were no differences in moderate and severe osteomyelitis except the number of surgeries (2.8 ± 2.1 vs 4.1 ± 2.5; P < .01) and length of stay (18.6 ± 17.5 vs 28.2 ± 17.7; P < .01).

CONCLUSIONS

The IDSA classification better reflects outcomes if risk categories are stratified by STI or osteomyelitis and moderate and severe infections are not categorized separately.

Histopathologic findings in culture-positive secondary osteomyelitis

As peripheral vascular disease and diabetes mellitus are increasingly common, chronic wounds are often seen. Bone biopsies, with imaging and microbial cultures, are often obtained to evaluate for osteomyelitis. Because much of the historical literature describing the histology of osteomyelitis pertains to primary osteomyelitis, this study characterizes the histologic findings and provides correlation with culture results in secondary osteomyelitis. The histologic features of bone biopsies were assessed over a 5 year period. Concurrent laboratory and radiographic data were obtained and these data were compared with culture results. This study included 163 cases, of which 104 were culture-positive osteomyelitis. All culture-positive cases had been present longer than 28 days and had at least one of the following histologic features: neutrophilic inflammation, plasmacytic inflammation, or eosinophilic fibrosis. However, none of these findings were restricted to culture-positive cases. Overall, plasmacytic and neutrophilic inflammation provided similar specificity, and positive predictive values for osteomyelitis. Medullary fibrosis gave a sensitivity of 95%, the highest for any single feature, and the combination of fibrosis and neutrophilic inflammation had the greatest specificity of 96%. Additionally, neutrophilic inflammation correlated often with isolation of Staphylococcus aureus, while plasma cell predominance was found more frequently with other infectious agents. This study describes histologic features in secondary osteomyelitis, which may challenge the widespread inclination to equate a neutrophilic inflammation with 'acute osteomyelitis' and 'chronic osteomyelitis' with one rich in plasma cells. We report an early correlation between common histopathologic findings and specific culture isolates, which can be further refined with additional research.

Role of inflammatory markers in the healing time of diabetic foot osteomyelitis treated by surgery or antibiotics

OBJECTIVE

To analyse the predictive role of inflammatory markers in the healing time of diabetic foot osteomyelitis treated by surgery or antibiotics.

METHODS

An observational study of patients with diabetic foot ulcers (DFU) and clinically suspected osteomyelitis. The patients underwent surgical or antibiotic treatment for bone infection in a specialised diabetic foot unit. Blood samples were taken from each patient to analyse biomarkers. The main outcome was the number of weeks until healing occurred.

RESULTS

A total of 116 patients took part in the study. The number of weeks until healing was similar for both groups (surgical n=96 and antiobiotic n=20, treatments). No association was observed among biomarkers as predictors of time-to-healing.

CONCLUSION

There is not enough evidence to define the prognostic role of inflammatory markers in the healing time of DFUs complicated with diabetic foot osteomyelitis, regardless of the treatment administered.

The infected diabetic foot: Can serum biomarkers predict osteomyelitis after hospital discharge for diabetic foot infections?

The aim of this study is to evaluate serum biomarkers to monitor high-risk patients for reinfection of bone. Thirty-five patients were prospectively enrolled with moderate to severe diabetic foot infections with suspicion of osteomyelitis. Bone samples were obtained for culture and histology. Clinical characteristics and outcomes of patients were compared using χ² square test. Biomarkers (white blood cell count, erythrocyte sedimentation rate, c-reactive protein, procalcitonin, interleukin-6, interleukin-8, and monocyte chemoattractant protein 1) were assessed at baseline, 3, and 6 weeks after treatment initiation and evaluated for correlation with reinfection of bone. After 6 weeks of antibiotic treatment, ESR at 73.5 mm/h (sensitivity 62.5%, specificity 100%, area under the receiver operating characteristic (AUROC) 0.7839, 95% CI 0.54-1.00, P < .01) and IL-8 at 15.09 mg/dL (sensitivity 42.9%, specificity 92.0% AUROC 0.6286, 95% CI 0.36-0.90, P = .0496) were associated with reinfection of bone. An increase in IL-8 from week 0 to 6 >0.95 mg/dL was associated with reinfection (sensitivity 71%, specificity 72% AUROC 0.7057, 95% CI 0.49-0.92, P = .04). An ESR change from week 0-6 of -16.5% (sensitivity 71.4%, specificity 86.4% AUROC 0.7403, 95% CI 0.48-1.00, P = .02), CRP (-)74.4% (sensitivity 66.7%, specificity 91.3% AUROC 0.7174, 95% CI 0.40-1.00, P = .04), IL-6 (-)49.9% (sensitivity 71.4%, specificity 76% AUROC 0.7371, 95% CI 0.47-1.00, P = .04), and IL-8 29% (sensitivity 85.7%, specificity 56.0% AUROC of 0.7343, 95% CI 0.54-0.93, P = .048) were associated with increased risk of reinfection. Pilot data suggest that serum biomarkers (ESR, IL8 and IL6, MCP-1) may be correlated with developing osteomyelitis and could be used to monitor high-risk patients for reinfection.

Diagnosing Osteomyelitis: A Histology Guide for Pathologists

Histopathologic examination of bone specimens coupled with bone culture is considered the gold standard for the diagnosis of osteomyelitis (OM). Despite this, studies have demonstrated interpathologist agreement in the diagnosis of OM as low as 30%, largely stemming from a lack of specific definitions and diagnostic criteria. Review of the literature has provided insight into the lifecycle of OM, illustrating the histologic progression of OM phases from acute to chronic, and provides support for defining subcategories of OM. Using an algorithmic histopathologic tool consisting of 15 criteria, each with an associated score, we defined 5 categories of OM: (1) acute OM, (2) acute and chronic OM, (3) chronic OM, (4) chronic active OM, and (5) chronic inactive OM. We reviewed 462 microscopic slides from 263 patients with suspected OM, and for each slide, we determined an algorithm-derived diagnosis, which was then used to calculate a total histopathologic load score (Jupiter score). Algorithm-derived diagnoses recapitulated original clinical diagnoses and diagnosed cases as OM that had not been originally diagnoses. These novel cases were more likely to have subsequent clinical complications. Finally, pathologic load scores were assessed for association with the category of OM.

Making the equivocal unequivocal: standardization of clean margins in diabetic foot osteomyelitis

Background

The prevalence of diabetes mellitus continues to rise. Diabetic foot ulcers with osteomyelitis are a diabetes-related complication presenting a significant burden to this cohort. A cure to diabetic foot osteomyelitis remains elusive and standard of care has failed to improve outcomes. To advance research and better patient outcomes, the authors offer specific guidance with terminology to enhance operative dictations which may improve surgical practice and guide treatment.

Methods

A consecutive review of podiatric surgical dictations for inpatient diabetic foot osteomyelitis within a tertiary care facility was performed. Surgical descriptors of bone were standardized: density, anatomic structure, vascular thrombosis, color, and draining sinus. Correlations between the five categories and histopathological results were performed after kappa analysis for interrater reliability was performed.

Results

Kappa coefficient demonstrated high inter-reliability of surgical findings. This suggests potential agreement amongst surgeons performing similar procedures. It was also found that specific bone descriptors had moderate to strong correlation with clean histopathologic bone margins when biopsied. This further suggests that the use of standardized terms may help guide definitive therapy.

Conclusions

The authors suggest a standardized approach which includes consistent descriptors of intraoperative bone. With use of standardized terms, vague and blanket descriptors are eliminated. This has potential to improve understanding of changes within bone as a result of infection and diabetes. Early and improved communication of intraoperative findings will enhance the multidisciplinary approach. This could potentially lead to changes in diabetic foot management and may limit hospital waste waiting for final cultures and pathology reports.

Short duration of post-amputation antibiotic therapy in diabetic foot patients with total resection of osteomyelitis

BACKGROUND

Short duration of post-amputation antibiotic therapy (2-5 days) is recommended in patients with diabetic foot osteomyelitis after total resection of infected bone tissue.

OBJECTIVE

To evaluate the long-term effectiveness of short-duration post-amputation antibiotic therapy in diabetic patients with total resection of osteomyelitis assessed by sterile bone bacteriological samples obtained from the resection margin.

METHODS

The endpoint was the absence of osteomyelitis relapse at 6 months, defined as recurrence of osteomyelitis with the need for surgical revision and/or new bone antibiotic therapy.

RESULTS

Among 15 patients included, 12 (80%) were cured without recurrence of osteomyelitis at 6 months, with a mean duration of antibiotic therapy of 8.3±5.9 days post surgery. This result is comparable to literature data, while all of them reported longer duration of antibiotic therapy and/or shorter follow-up.

CONCLUSION

Short duration of post-amputation antibiotic therapy in diabetic patients with sterile bacteriological samples obtained from resection margin seems effective.

Diagnosing diabetic foot osteomyelitis

Bone involvement during an infection of the diabetic foot represents a serious complication associated with a high risk of amputation, prolonged antibiotic treatment and hospitalization. Diabetic foot osteomyelitis (DFOs) require a multidisciplinary approach given the usual complexity of these situations. DFO should be suspected in most cases especially in the most severe forms of soft tissue diabetic foot infections (DFIs) where the prevalence of bone infection may be up to 60%. Suspicion is based on clinical signs in particular a positive probe-to-bone (PTB) test, elevated inflammatory biomarkers especially erythrocyte sedimentation rate and abnormal imaging assessment using plain X-ray as a first-line choice. The combination of PTB test with plain X-ray has proven effective in the diagnosis of DFO. The confirmation (definite) diagnosis of DFO is based on the results of a bone sample examination obtained by either surgical or percutaneous biopsy. Sophisticated imaging examinations such as Magnetic Resonance Imaging (MRI) and nuclear imaging techniques are useful where doubt persists after first-line imaging assessment. These techniques may also help localize the bone infection site and increase the diagnostic performance of percutaneous bone biopsy. The quality of the microbiological documentation of DFO is likely to improve the adequacy of the antimicrobial therapy especially when medical (ie, no surgical resection of the infected bone tissues) is considered. The use of new (molecular) techniques for the identification of the bone pathogens have not yet proven superiority on classic cultural techniques for the management of such patients.

Impact of diagnostic bone biopsies on the management of non-vertebral osteomyelitis: A retrospective cohort study

Optimal antibiotic management of patients with osteomyelitis remains a challenge for many clinicians. Although image-guided bone biopsy (IGB) remains the gold standard, its role in confirming diagnosis and guiding antibiotic management is not clear in patients with non-vertebral osteomyelitis.To determine the diagnostic yield of IGB and its impact on antibiotic management in non-vertebral osteomyelitis.Retrospective cohort study.Urban academic medical center.Patients admitted for non-vertebral osteomyelitis who underwent image-guided bone biopsy.Primary outcomes were microbiologic and histopathological results. We evaluated the impact of IGB on clinician-initiated changes in antibiotic regimen before and after biopsy.We evaluated 203 bone biopsies in 185 patients with clinical suspicion of osteomyelitis. 79% of patient received antibiotics prior to biopsy. Bone cultures were positive in 28% and histopathology confirmed osteomyelitis in 29%, but concordance was poor. Furthermore, clinical suspicion of infection was much higher, given that 68% received empiric antibiotics. Leukocytosis was significantly associated with positive cultures in multivariate analysis. There was no statistically significant correlation between antibiotic management and bone culture results. When culture yielded an organism, empiric regimens were kept the same, broadened or narrowed with equal frequency; targeted regimens were chosen only in 4 cases. Despite negative cultures in 98/138 cases having received empiric treatment, antibiotics were discontinued in only 8 cases. Even when empiric treatment was not given, negative cultures did not dissuade clinicians from eventual antibiotic use in a significant number of cases (17/48). In 46/71 patients whose final regimen included vancomycin, there was no evidence of current or past infection with MRSA.In patients with non-vertebral osteomyelitis, the diagnostic yield of image-guided bone biopsy is low, and clinicians frequently make decisions regarding antibiotic management that are not aligned with culture results.

Are We Misdiagnosing Diabetic Foot Osteomyelitis? Is the Gold Standard Gold?

To compare the incidence of osteomyelitis based on different operational definitions using the gold standard of bone biopsy, we prospectively enrolled 35 consecutive patients who met the criteria of ≥21 years of age and a moderate or severe infection based on the Infectious Diseases Society of America classification. Bone samples were obtained from all patients by percutaneous bone biopsy or intraoperative culture if the patient required surgery. Bone samples were analyzed for conventional culture, histology, and 16S ribosomal RNA genetic sequencing. We evaluated 5 definitions for osteomyelitis: 1) traditional culture, 2) histology, 3) genetic sequencing, 4) traditional culture and histology, and 5) genetic sequencing and histology. There was variability in the incidence of osteomyelitis based on the diagnostic criteria. Traditional cultures identified more cases of osteomyelitis than histology (68.6% versus 45.7%, p = .06, odds ratio [OR] 2.59, 95% confidence interval [CI] 0.98 to 6.87), but the difference was not significant. In every case that histology reported osteomyelitis, bone culture was positive using traditional culture or genetic sequencing. The 16S ribosomal RNA testing identified significantly more cases of osteomyelitis compared with histology (82.9% versus 45.7%, p = .002, OR 5.74, 95% CI 1.91 to 17.28) and compared with traditional cultures but not significantly (82.9% versus 68.6%, p = .17, OR 2.22, 95% CI 0.71 to 6.87). When both histology and traditional culture (68.6%) or histology and genetic sequencing cultures (82.9%) were used to define osteomyelitis, the incidence of osteomyelitis did not change. There is variability in the incidence of osteomyelitis based on how the gold standard of bone biopsy is defined in diabetic foot infections.

Modern management of diabetic foot osteomyelitis. The when, how and why of conservative approaches

INTRODUCTION

Diabetic foot osteomyelitis (DFO) has long been considered a complex infection that is both difficult to diagnose and treat, and is associated with a high rate of relapse and limb loss. Areas covered: DFO can usually be diagnosed by a combination of clinical evaluation, serum inflammatory markers and plain X-ray. When the results of these procedures are negative or contradictory, advanced imaging tests or bone biopsy may be necessary. Staphylococcus aureus remains the most frequent microorganism isolated from bone specimens, but infection is often polymicrobial. Antibiotic therapy, preferably with oral agents guided by results of bone culture, for a duration of no more than six weeks, appears to be as safe and effective as surgery in cases of uncomplicated forefoot DFO. Surgery (which should be limb-sparing when possible) is always required for DFO accompanied by necrotizing fasciitis, deep abscess, gangrene or in cases not responding (either clinically or radiographically) to apparently appropriate antibiotic treatment. Expert commentary: Research in the past decade has improved diagnosis and treatment of DFO, and most cases can now be managed with a 'conservative' approach, defined as treatment either exclusively with antibiotics or with surgery removing as little bone and soft tissue as necessary.

Diagnostic and therapeutic update on diabetic foot osteomyelitis

Diabetic foot osteomyelitis (DFO) is the most common infection associated to diabetic foot ulcers (DFU). This review is designed to provide an update on the diagnosis and treatment of DFO based on an analysis of MEDLINE through PubMed using as search criterion "Diabetic Foot Osteomyelitis". Authors have included in this review the most relevant manuscripts regarding diagnosis and treatment of DFO. After review and critical analysis of publications, it may be concluded that diagnosis of DFO is not simple because of its heterogeneous presentation. Clinical inflammatory signs, probe-to-bone test, and plain X-rays are postulated as the basic tests for clinical diagnosis when DFO is suspected. Diagnosis should be supported by laboratory tests, of which ESR (>70mm/h) has been shown to be most precise. MRI is the most accurate imaging test, especially for differential diagnosis with Charcot foot. Pathogen isolation by bone culture is essential when the patient is treated with ATB only. Medical or surgical treatment should be based on the clinical characteristics of the patient and the lesion. Surgery should always be an option if medical treatment fails.

Integrative analysis of miRNA and mRNA paired expression profiling of primary fibroblast derived from diabetic foot ulcers reveals multiple impaired cellular functions

Diabetic foot ulcers (DFUs) are one of the major complications of diabetes. Its molecular pathology remains poorly understood, impeding the development of effective treatments. Although it has been established that multiple cell types, including fibroblasts, keratinocytes, macrophages, and endothelial cells, all contribute to inhibition of healing, less is known regarding contributions of individual cell type. Thus, we generated primary fibroblasts from nonhealing DFUs and evaluated their cellular and molecular properties in comparison to nondiabetic foot fibroblasts (NFFs). Specifically, we analyzed both micro-RNA and mRNA expression profiles of primary DFU fibroblasts. Paired genomic analyses identified a total of 331 reciprocal miRNA-mRNA pairs including 21 miRNAs (FC > 2.0) along with 239 predicted target genes (FC > 1.5) that are significantly and differentially expressed. Of these, we focused on three miRNAs (miR-21-5p, miR-34a-5p, miR-145-5p) that were induced in DFU fibroblasts as most differentially regulated. The involvement of these microRNAs in wound healing was investigated by testing the expression of their downstream targets as well as by quantifying cellular behaviors in prospectively collected and generated cell lines from 15 patients (seven DFUF and eight NFF samples). We found large number of downstream targets of miR-21-5p, miR-34a-5p, miR-145-5p to be coordinately regulated in mRNA profiles, which was confirmed by quantitative real-time PCR. Pathway analysis on paired miRNA-mRNA profiles predicted inhibition of cell movement and cell proliferation, as well as activation of cell differentiation and senescence in DFU fibroblasts, which was confirmed by cellular assays. We concluded that induction of miR-21-5p, miR-34a-5p, miR-145-5p in DFU dermal fibroblasts plays an important role in impairing multiple cellular functions, thus contributing to overall inhibition of healing in DFUs.

Challenges in diagnosing infection in the diabetic foot

Diagnosing the presence of infection in the foot of a patient with diabetes can sometimes be a difficult task. Because open wounds are always colonized with microorganisms, most agree that infection should be diagnosed by the presence of systemic or local signs of inflammation. Determining whether or not infection is present in bone can be especially difficult. Diagnosis begins with a history and physical examination in which both classic and 'secondary' findings suggesting invasion of microorganisms or a host response are sought. Serological tests may be helpful, especially measurement of the erythrocyte sedimentation rate in osteomyelitis, but all (including bone biomarkers and procalcitonin) are relatively non-specific. Cultures of properly obtained soft tissue and bone specimens can diagnose and define the causative pathogens in diabetic foot infections. Newer molecular microbial techniques, which may not only identify more organisms but also virulence factors and antibiotic resistance, look very promising. Imaging tests generally begin with plain X-rays; when these are inconclusive or when more detail of bone or soft tissue abnormalities is required, more advanced studies are needed. Among these, magnetic resonance imaging is generally superior to standard radionuclide studies, but newer hybrid imaging techniques (single-photon emission computed tomography/computed tomography, positron emission tomography/computed tomography and positron emission tomography/magnetic resonance imaging) look to be useful techniques, and new radiopharmaceuticals are on the horizon. In some cases, ultrasonography, photographic and thermographic methods may also be diagnostically useful. Improved methods developed and tested over the past decade have clearly increased our accuracy in diagnosing diabetic foot infections.

Influence of the Location of Nonischemic Diabetic Forefoot Osteomyelitis on Time to Healing After Undergoing Surgery

The forefoot has been reported as the most frequent location of osteomyelitis in the feet of patients with diabetes. The forefoot includes toes and metatarsal heads as common locations of bone infections, but the anatomy of these bones is quite different. As a result, such differences in anatomy may have an impact on the outcomes. The aim of the present study was to determine whether different locations of osteomyelitis in the forefoot have any influence on time to healing after undergoing surgery in a prospective series including 195 patients without peripheral arterial disease and osteomyelitis confirmed by histopathology. Location of the lesion was classified into 4 groups: hallux, first metatarsal head, lesser metatarsal heads, and lesser toes. The time required to achieve healing and the cumulative rate of wounds healed and likelihood of healing were analyzed at 4, 8, and 12 weeks after surgery. Time of healing (mean ± SD) in the whole series was 10.7 ± 8.4 weeks. Osteomyelitis located in the lesser toes has a higher probability of healing by the fourth week (odds ratio [OR] = 5.7, 95% confidence interval [CI] = 2.8-11.6, P < .001), eighth week (OR = 3.2, 95% CI = 1.6-6.4, P < .001), or twelfth week (OR = 3.1, 95% CI = 1.3-7.0, P = .008) than other osteomyelitis locations. Osteomyelitis located in the first metatarsal joint was less likely to heal by the eighth week (OR = 0.4, 95% CI = 0.2-0.9, P = .037) and 12th week (OR = 0.4, 95% CI = 0.2-1.0, P = .040). In conclusion, time to healing is significantly different according to the location of the bone infection in the forefoot.