Management of osteomyelitis of the foot in diabetes mellitus

Janus liposozyme for the modulation of redox and immune homeostasis in infected diabetic wounds

Diabetic foot ulcers often become infected, leading to treatment complications and increased risk of loss of limb. Therapeutics to manage infection and simultaneously promote healing are needed. Here we report on the development of a Janus liposozyme that treats infections and promotes wound closure and re-epithelialization. The Janus liposozyme consists of liposome-like selenoenzymes for reactive oxygen species (ROS) scavenging to restore tissue redox and immune homeostasis. The liposozymes are used to encapsulate photosensitizers for photodynamic therapy of infections. We demonstrate application in methicillin-resistant Staphylococcus aureus-infected diabetic wounds showing high ROS levels for antibacterial function from the photosensitizer and nanozyme ROS scavenging from the liposozyme to restore redox and immune homeostasis. We demonstrate that the liposozyme can directly regulate macrophage polarization and induce a pro-regenerative response. By employing single-cell RNA sequencing, T cell-deficient Rag1-/- mice and skin-infiltrated immune cell analysis, we further reveal that IL-17-producing γδ T cells are critical for mediating M1/M2 macrophage transition. Manipulating the local immune homeostasis using the liposozyme is shown to be effective for skin wound repair and tissue regeneration in mice and mini pigs.

Pharmacological elevation of sphingosine-1-phosphate by S1P lyase inhibition accelerates bone regeneration after post-traumatic osteomyelitis

Posttraumatic osteomyelitis and the ensuing bone defects are a debilitating complication after open fractures with little therapeutic options. We have recently identified potent osteoanabolic effects of sphingosine-1-phosphate (S1P) signalling and have now tested whether it may beneficially affect bone regeneration after infection. We employed pharmacological S1P lyase inhibition by 4-deoxypyrodoxin (DOP) to raise S1P levels in vivo in an unicortical long bone defect model of posttraumatic osteomyelitis in mice. In a translational approach, human bone specimens of clinical osteomyelitis patients were treated in organ culture in vitro with DOP. Bone regeneration was assessed by μCT, histomorphometry, immunohistology and gene expression analysis. The role of S1P receptors was addressed using S1PR3 deficient mice. Here, we present data that DOP treatment markedly enhanced osteogenesis in posttraumatic osteomyelitis. This was accompanied by greatly improved osteoblastogenesis and enhanced angiogenesis in the callus accompanied by osteoclast-mediated bone remodelling. We also identified the target of increased S1P to be the S1PR3 as S1PR3-/- mice showed no improvement of bone regeneration by DOP. In the human bone explants, bone mass significantly increased along with enhanced osteoblastogenesis and angiogenesis. Our data suggest that enhancement of S1P/S1PR3 signalling may be a promising therapeutic target for bone regeneration in posttraumatic osteomyelitis.

Sodium-glucose co-transporter-2 inhibitor (SGLT2i) treatment and risk of osteomyelitis: A pharmacovigilance study of the FAERS database

Background and purpose: Several clinical trials have indicated that the use of canagliflozin increases the risk of lower extremity amputation. Although the US Food and Drug Administration (FDA) has withdrawn its black box warning about amputation risk for canagliflozin, the risk still exists. We sought to estimate the association between hypoglycemic medications, especially sodium-glucose co-transporter-2 inhibitors (SGLT2is), and adverse events (AEs) before the irreversible outcome of amputation as a promising early warning, based on the FDA Adverse Event Reporting System (FAERS) data. Methods: Publicly available FAERS data were analyzed using a reporting odds ratio (ROR) method and validated by a Bayesian confidence propagation neural network (BCPNN) method. The developing trend of the ROR was investigated by a series of calculations based on the accumulation of data in the FAERS database quarter by quarter. Results: Ketoacidosis, infection, peripheral ischemia, renal impairment, and inflammation including osteomyelitis might be more likely to occur among users of SGLT2is, especially canagliflozin. Osteomyelitis and cellulitis are AEs unique to canagliflozin. Among 2,888 osteomyelitis-related reports referring to hypoglycemic medications, 2,333 cases were associated with SGLT2is, with canagliflozin accounting for 2,283 of these cases and generating an ROR value of 360.89 and a lower limit of information component (IC₀₂₅) of 7.79. No BCPNN-positive signal could be generated for drugs other than insulin and canagliflozin. Reports suggesting that insulin could generate BCPNN-positive signals span from 2004 to 2021, whereas reports with BCPNN-positive signals emerged only since the second quarter (Q2) of 2017, 4 years since the approval of SGLT2is in Q2 of 2013, for canagliflozin and drug groups containing canagliflozin. Conclusion: This data-mining investigation revealed a strong association between canagliflozin treatment and developing osteomyelitis that might be a crucial forewarning to lower extremity amputation. Further studies with updated data are needed to better characterize the risk of osteomyelitis associated with SGLT2is.

MRI and Clinical Risk Indicators for Osteomyelitis

Introduction. The sensitivity and specificity for magnetic resonance imaging (MRI) diagnosis of osteomyelitis is 90% and 80%, respectively; findings include bone marrow edema, T2-weighted image hyperintensity (HI-T2WI), T1-weighted image confluent signal(CS-T1WI), and cortical erosion (CE). The goal is to determine which risk factors and MRI findings are most predictive of osteomyelitis. Materials and Methods. After institutional review board approval, records of patients who underwent bone biopsy of the foot/ankle between 2015 and 2017 were reviewed. Diagnosis was determined histologically. Blinded MRI review identified indicators of osteomyelitis: HI-T2WI, CS-T1WI, ulcer depth, and CE. Bivariate and multivariate regression determined an association between osteomyelitis and radiographic indicators. Results. Of 59 subjects, 41 (69.5%) and 18 (30.5%) had pathologic evidence of osteomyelitis or were indeterminate. The sensitivity and specificity by radiologist diagnosis was 51.4% and 91.7%, respectively. Diabetes (relative risk [RR]=2.9, 95% CI = 1.0.8-7.77, P = .034), CS-T1WI (RR = 1.6, 95% CI = 1.23-2.20, P < .001), and CE (RR = 1.8, 95% CI = 1.34-2.28, P < .001) were risk factors on bivariate analysis. Ulcer depth demonstrated a trend toward statistical significance. Diabetes (RR = 2.4, 95% CI = 1.00-5.69, P = .049) and CE (RR = 1.7, 95% CI = 1.27-2.37, P < .001) were independent risk factors on multivariate analysis. Discussion. Diabetes and CS-T1WI are independent risk factors for pedal osteomyelitis. Patients with diabetes, CS-T1WI, and CE should be evaluated for osteomyelitis with recommendation for bone biopsy in appropriate clinical settings.Levels of Evidence: Level III Retrospective Comparative Study.

99mTc-white blood cell SPECT/CT to assess diabetic foot osteomyelitis remission: contribution of semi-quantitative scoring system

AIMS

We previously reported that 99mTc-White blood cell (WBC) single-photon emission computed tomography (SPECT/CT) could be a useful tool to assess diabetic foot osteomyelitis (DFO) remission and guide the duration of antibiotic treatment. The aim of the present study was to evaluate the performance and reproducibility of two analysis methods to diagnose DFO remission using 99mTc-WBC-SPECT/CT.

METHODS

99mTc-WBC-SPECT/CT performed for patients with DFO at the end of antibiotic treatment were retrospectively read by two nuclear physicians (one senior and one junior). Assessment by conventional visual analysis and by the use of a semi-quantitative scoring system, the composite score index (CSI), was performed. The performance and reproducibility of methods were compared between the two nuclear physicians. Successful treatment of DFO was defined by the absence of DFO relapse at the same site within 1 year.

RESULTS

A total of 68 patients with 74 DFO were included. Three were excluded from the analysis due to the low quality of SPECT/CT; among the 71 DFO analyzed, 11 (15.5%) had a relapse during follow-up. Performances of 99mTc-WBC-SPECT/CT to predict DFO remission with conventional visual assessment were significantly lower for junior than for senior nuclear physician with moderate inter-rater agreement (Kappa: 0.417). Performances with the use of CSI were similar between the two readers with good inter-rater agreement (Kappa: 0.756).

CONCLUSION

The study found that conventional visual assessment of 99mTc-WBC-SPECT/CT to assess DFO remission requires experience, and supported that CSI could be useful for junior nuclear physician to discriminate residual infections and inflammatory post-treatment uptake.

The Characteristics and Mortality of Osteoporosis, Osteomyelitis, or Rheumatoid Arthritis in the Diabetes Population: A Retrospective Study

BACKGROUND

Patients with diabetes mellitus are prone to develop osteoporosis, osteomyelitis, or rheumatoid arthritis (RA). Furthermore, the presence of these complications in those with diabetes may lead to higher mortality. The aim of our study was to assess characteristics and mortality of osteoporosis, osteomyelitis, or rheumatoid arthritis in individuals with diabetes.

METHODS

We analyzed osteoporosis, osteomyelitis, and RA deaths associated with diabetes from 1999-2017 using the CDC WONDER system (CDC WONDER; https://wonder.cdc.gov). We used ICD-10 codes to categorize the underlying and contributing causes of death. Crude mortality rates (CMR) and age-adjusted mortality rates (AAMR) per 1,000,000 person-years were calculated.

RESULTS

The AAMR for osteoporosis in the population with diabetes was significantly higher in females (AAMR: 4.17, 95% CI: 4.10-4.24) than in males (AAMR: 1.12, 95% CI: 1.07-1.16). Deaths due to osteoporosis increased gradually from 1999, peaked in 2003 (AAMR: 3.78, 95% CI: 3.55-4.00), and reached a nadir in 2016 (AAMR: 2.32, 95% CI: 2.15-2.48). The AAMR for RA associated with diabetes was slightly higher in females (AAMR: 4.04, 95% CI: 3.98-4.11) than in males (AAMR: 2.45, 95% CI: 2.39-2.51). The mortality rate due to RA increased slightly from 1999 (AAMR: 3.18, 95% CI: 2.97-3.39) to 2017 (AAMR: 3.20, 95% CI: 3.02-3.38). The AAMR for osteomyelitis associated with diabetes was higher in males (AAMR: 4.36, 95% CI: 4.28-4.44) than in females (AAMR: 2.31, 95% CI: 2.26-2.36). From 1999 to 2017, the AAMR from osteomyelitis in this population was 2.63 (95% CI: 2.44-2.82) per 1,000,000 person-years in 1999 and 4.25 (95% CI: 4.05-4.46) per 1,000,000 person-years in 2017.

CONCLUSIONS

We found an increase in the age-adjusted mortality rates of RA and osteomyelitis and a decrease of osteoporosis associated with diabetes from 1999 to 2017. We suggest that increased attention should therefore be given to these diseases in the population with diabetes, especially in efforts to develop preventative and treatment strategies.

Limb Salvage and Prevention of Ulcer Recurrence in a Chronic Refractory Diabetic Foot Osteomyelitis

Biomechanical changes caused by structural foot deformities predispose patients to plantar ulceration. Plantar ulcer recurrence often leads to osteomyelitis, which is more commonly observed in patients with diabetes. Once the infection of diabetic foot ulcer (DFU) spreads and is complicated by osteomyelitis, treatment becomes more complicated and difficult. Osteomyelitis treatment remains challenging because of low drug concentration within the tissue caused by poor circulation and inadequate localized nutrition. Moreover, tissues around plantar ulcers are fewer and are thin, making the formation of granulation tissues difficult due to elevated plantar pressure. Furthermore, the skin around the wound is excessively keratinized, and the epidermis is hard to regenerate. Meanwhile, skin grafting at that site is often not successful due to poor blood circulation. Therefore, it is technically challenging to manage diabetic pressure plantar ulcer with osteomyelitis and prevent its recurrence. Here, we present a case of chronic DFU complicated by osteomyelitis due to foot deformity. The ulcer was successfully healed using advanced wound repair technology comprising of surgical bone resection, vancomycin-loaded bone cement implant, negative-pressure wound therapy, and autologous platelet-rich gel. Subsequently, preventive foot care with custom-made offloading footwear was prescribed. The plantar ulcer did not recur and improvement in biomechanical parameters was observed after the intervention. This case represents an effective and comprehensive management strategy for limb salvage and prevention in patients with complicated foot conditions.

Double-Stranded RNA Is a Novel Molecular Target in Osteomyelitis Pathogenesis: A Translational Avian Model for Human Bacterial Chondronecrosis with Osteomyelitis

Osteomyelitis remains a serious inflammatory bone disease that affects millions of individuals worldwide and for which there is no effective treatment. Despite scientific evidence that Staphylococcus bacteria are the most common causative species for human bacterial chondronecrosis with osteomyelitis (BCO), much remains to be understood about the underlying virulence mechanisms. Herein, we show increased levels of double-stranded RNA (dsRNA) in infected bone in a Staphylococcus-induced chicken BCO model and in human osteomyelitis samples. Administration of synthetic [poly(I:C)] or genetic (Alu) dsRNA induces human osteoblast cell death. Similarly, infection with Staphylococcus isolated from chicken BCO induces dsRNA accumulation and cell death in human osteoblast cell cultures. Both dsRNA administration and Staphylococcus infection activate NACHT, LRR and PYD domains-containing protein (NLRP)3 inflammasome and increase IL18 and IL1B gene expression in human osteoblasts. Pharmacologic inhibition with Ac-YVAD-cmk of caspase 1, a critical component of the NLRP3 inflammasome, prevents DICER1 dysregulation- and dsRNA-induced osteoblast cell death. NLRP3 inflammasome and its components are also activated in bone from BCO chickens and humans with osteomyelitis, compared with their healthy counterparts. These findings provide a rationale for the use of chicken BCO as a human-relevant spontaneous animal model for osteomyelitis and identify dsRNA as a new treatment target for this debilitating bone pathogenesis.

Systematic review of randomized controlled trials on antibiotic treatment for osteomyelitis in diabetes

AIM

To evaluate the efficacy of antibiotic therapy in osteomyelitis treatment among people with diabetes.

METHODS

A systematic search of PubMed, EMBASE, AMED, Web of Science, the WHO trial registry, Cochrane library databases, and ClinicalTrials.gov, in addition to hand-searching, was undertaken in July 2018. Two reviewers independently extracted data. The studies' methodological quality was assessed using the modified Jadad scale. Descriptive analysis was performed.

RESULTS

Seven randomized controlled trials, with 393 participants in total, were included. The antibiotic regimens, treatments and follow-up durations varied among the trials. The total scores showed that the overall methodological quality of the seven studies was high, despite two studies showing some flaws in double-blinding and withdrawals/drop-outs. Of four studies comparing different antibiotic regimens, three implied a similar remission effect, while one implied that ertapenem ± vancomycin treatment showed a higher remission rate than tigecycline treatment; this conclusion was not robust because of low power and small sample size. In the other three studies, which included two different doses of ciprofloxacin, an antibiotics group and a conservative surgical group, and two durations of the same antibiotic strategy, no significant differences in remission were reported between the groups. No difference was observed in the analyses of microbiological outcomes, superinfections and relapse, except adverse events.

CONCLUSIONS

There is no definitive evidence supporting the superiority of any particular antibiotic agent, dose, or administration duration in the treatment of osteomyelitis in diabetes. As the included studies had some flaws and limitations, further research is necessary.

Level of Agreement With a Multi-Test Approach to the Diagnosis of Diabetic Foot Osteomyelitis

Although bone biopsy has historically been considered the "gold standard" or "standard reference" for the diagnosis of diabetic foot osteomyelitis, some contemporary investigations have provided evidence against this as a single diagnostic test and in support of a combination of clinical, laboratory, and radiographic findings. The objective of this investigation was to measure the level of agreement between several commonly used forms of diagnostic testing for diabetic foot osteomyelitis. A retrospective chart review was performed of 50 consecutive patients admitted to a single tertiary healthcare center with the documented performance of 1) a clinical probe-to-bone test on hospital admission; 2) plain film radiographs prior to any surgical intervention; 3) magnetic resonance imaging prior to any surgical intervention; and an intraoperative excisional bone debridement performed, with samples sent for both 4) histologic analysis and 5) microbiologic analysis. A frequency count of agreement among these 5 tests was performed, and the interobserver (or inter-test) agreement was measured using the kappa statistic. We observed low levels of inter-test agreement between the 5 diagnostic tests (range 42.0%-62.0%), and levels of chance-corrected agreement were well below what would be considered appropriate for a "gold standard" or "standard reference." Levels of the kappa statistic ranged from 0.0 to 0.220, with most inter-test comparisons falling in the "poor agreement" and "slight agreement" interpretation ranges. The highest level of agreement occurred between the plain film radiographs and magnetic resonance imaging (62.0% agreement and kappa statistic of 0.220). Although it is likely that a combination of clinical, radiographic, and laboratory tests provides the best diagnostic approach for diabetic foot osteomyelitis, the data provided herein indicate that the tests themselves might have high intrinsic levels of unreliability and that the specific combination of tests that might be best used remains unclear.

The Superiority of Removable Contact Splints in the Healing of Diabetic Foot during Postoperative Care

OBJECTIVE

Off-loading is one of the crucial components of diabetic foot (DF) therapy. However, there remains a paucity of studies on the most suitable off-loading for DF patients under postoperative care. The aim of our study was to evaluate the effect of different protective off-loading devices on healing and postoperative complications in DF patients following limb preservation surgery.

METHODS

This observational study comprised 127 DF patients. All enrolled patients had undergone foot surgery and were off-loaded empirically as follows: wheelchair+removable contact splint (RCS) (group R: 29.2%), wheelchair only (group W: 48%), and wheelchair+removable prefabricated device (group WP: 22.8%). We compared the primary (e.g., the number of healed patients, healing time, and duration of antibiotic (ATB) therapy) and secondary outcomes (e.g., number of reamputations and number and duration of rehospitalizations) with regard to the operation regions across all study groups.

RESULTS

The lowest number of postoperative complications (number of reamputations: p = 0.028; rehospitalizations: p = 0.0085; and major amputations: p = 0.02) was in group R compared to groups W and WP. There was a strong trend toward a higher percentage of healed patients (78.4% vs. 55.7% and 65.5%; p = 0.068) over a shorter duration (13.7 vs. 16.5 and 20.3 weeks; p = 0.055) in the R group, as well. Furthermore, our subanalysis revealed better primary outcomes in patients operated in the midfoot and better secondary outcomes in patients after forefoot surgery-odds ratios favouring the R group included healing at 2.5 (95% CI, 1.04-6.15; p = 0.037), reamputations at 0.32 (95% CI, 0.12-0.84; p = 0.018), and rehospitalizations at 0.22 (95% CI, 0.08-0.58; p = 0.0013).

CONCLUSIONS

This observational study suggests that removable contact splint combined with a wheelchair is better than a wheelchair with or without removable off-loading device for accelerating wound healing after surgical procedures; it also minimises overall postoperative complications, reducing the number of reamputations by up to 77% and the number of rehospitalizations by up to 66%.

Compassionate Use of Bacteriophage Therapy for Foot Ulcer Treatment as an Effective Step for Moving Toward Clinical Trials

We here present detailed descriptions of successful treatment of a series of diabetic toe ulcers using the Eliava BioPreparations' commercial preparation of the very well-studied anti-staphylococcal bacteriophage Sb-1. This chapter outlines what we feel is an appropriate mechanism to speed movement toward full-scale clinical trials with bacteriophage use to treat wound infections and to help address the crisis in antibiotic resistance.

Application of white blood cell SPECT/CT to predict remission after a 6 or 12 week course of antibiotic treatment for diabetic foot osteomyelitis

AIMS/HYPOTHESIS

Diabetic foot osteomyelitis is a major risk factor for amputation. Medical treatment allows remission in 53-82% of cases. However, the optimal duration of antibiotic therapy remains controversial as a validated marker of osteomyelitis remission is lacking. The aim of this cohort study was to assess prospectively the remission rate of diabetic foot osteomyelitis medically treated using white blood cell (WBC)-single-photon emission computed tomography (SPECT)/computed tomography (CT) as a predictive marker of remission.

METHODS

Individuals with diabetic foot osteomyelitis that was non-surgically treated between April 2014 and December 2015 were included. All participants were treated with antibiotics alone. WBC-SPECT/CT was performed at 6 weeks and antibiotic treatment discontinued if the clinical signs of soft-tissue infection had resolved and there was no abnormal uptake of labelled WBCs. Treatment was otherwise continued for a total of 12 weeks and then discontinued. For these individuals, another WBC-SPECT/CT was performed at 12 weeks. Remission was defined as the absence of recurrence of osteomyelitis at the same location at 1 year.

RESULTS

Forty-five individuals were included; overall remission rate was 84% at 1 year. A 6 week course of antibiotics was used in 23 participants, 22 of whom were in remission at 1 year (96%); a 12 week course was used for 22 participants, 16 of whom were in remission at 1 year (73%). Sensitivity of WBC-SPECT/CT at 12 weeks was 100%, specificity 56%, positive predictive value 46% and negative predictive value 100%.

CONCLUSIONS/INTERPRETATION

The study suggests that WBC-SPECT/CT could predict remission at the end of antibiotic treatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02927678.

CcpA Affects Infectivity of Staphylococcus aureus in a Hyperglycemic Environment

Many bacteria regulate the expression of virulence factors via carbon catabolite responsive elements. In Gram-positive bacteria, the predominant mediator of carbon catabolite repression is the catabolite control protein A (CcpA). Hyperglycemia is a widespread disorder that predisposes individuals to an array of symptoms and an increased risk of infections. In hyperglycemic individuals, the bacterium Staphylococcus aureus causes serious, life-threatening infections. The importance of CcpA in regulating carbon catabolite repression in S. aureus suggests it may be important for infections in hyperglycemic individuals. To test this suggestion, hyperglycemic non-obese diabetic (NOD; blood glucose level ≥20 mM) mice were challenged with the mouse pathogenic S. aureus strain Newman and the isogenic ccpA deletion mutant (MST14), and the effects on infectivity were determined. Diabetic NOD mice challenged with the ccpA deletion mutant enhanced the symptoms of infection in an acute murine pneumonia model relative to the parental strain. Interestingly, when diabetic NOD mice were used in footpad or catheter infection models, infectivity of the ccpA mutant decreased relative to the parental strain. These differences greatly diminished when normoglycemic NOD mice (blood glucose level ≤ 10 mM) were used. These data suggest that CcpA is important for infectivity of S. aureus in hyperglycemic individuals.

The association between chronic osteomyelitis and increased risk of diabetes mellitus: a population-based cohort study

Chronic inflammation is a well-known risk factor for type 2 diabetes mellitus (T2DM). The influence of chronic osteomyelitis (COM), an inflammatory disease, on the risk of developing T2DM remains unknown. This study investigated the risk of developing T2DM among COM patients. Using a retrospective cohort study, we identified 20,641 patients with COM and 82,564 age- and sex-matched controls for comparison from the Taiwan National Health Insurance Database (NHIRD) from 1997 to 2010. We followed up the COM cohort and the comparison cohort to compare the incidences of diabetes (ICD-9-CM code 250) until the end of 2010 or until the patients were censored because of death or withdrawal from the insurance program. The diabetes risk was analyzed using the Cox proportional hazards regression model. The incidence of T2DM was 1.6-fold higher in the group of COM patients than in the comparison group (29.1 vs. 18.2 per 10,000 person-years). The COM patients exhibited a higher diabetes risk [adjusted hazard ratio (aHR) = 1.64, 95 % confidence interval (CI) = 1.44-1.87] after controlling for the baseline and comorbidities. Younger and higher income patients exhibited a higher COM-to-reference incidence rate ratio (IRR) for T2DM compared with that of their counterparts. We also observed an increased risk of T2DM in COM patients with comorbidities (aHR = 1.70, 95 % CI = 1.47-1.96) compared with that of their non-COM counterparts. This is the first study to report the association between COM and an increased risk of developing T2DM, particularly among younger and higher income patients.

Clinical characteristics and risk factors of diabetic foot ulcer with multidrug-resistant organism infection

The objective was to determine multidrug-resistant organisms' (MDROs) profile in diabetic foot ulcers (DFU), antibiotic resistance of MDROs, and to find the potential risk factors for infection with MDROs. In 157 patients with DFU admitted to Tianjin Metabolic Disease Hospital, China, from January 2011 to January 2012, microbiological specimens were taken on admission. The patients were divided into 2 groups according to the infection of MDROs. Potential risk factors for MDRO-positive specimens were examined using univariate and multivariate analyses. Seventy-eight MDRO strains were isolated from patients in the MDRO+ group, among which the top 3 were Staphylococcus aureus (16.7%), Enterobacter spp (16.7%), and Pseudomonas aeruginosa (15.4%). Most of the MDROs were resistant to at least 8 kinds of commonly used antibiotics. Gram-negative MDROs showed 23% to 50% resistance to third-generation cephalosporins. The resistant rates of Gram-positive MDROs to fluoroquinolone were more than 70%; penicillin and semisynthetic penicillin were 57% to 100% resistant. Previous hospitalization (odds ratio [OR] = 3.000; 95% confidence interval [CI] = 1.100-8.182; P = .032), previous duration of antibiotic therapy (OR = 1.078; 95% CI = 1.001-1.160; P = .046), ulcer type (OR = 7.185; 95% CI = 2.115-24.408; P = .002), ulcer size (OR = 1.403; 95% CI = 1.042-1.888; P = .026), and osteomyelitis (OR = 3.390; 95% CI = 1.178-9.756; P = .024) were associated with MDRO infection in patients with DFU.

Osteomyelitis in the diabetic foot: diagnosis and management

Although osteomyelitis of the foot in diabetes remains common in specialist foot clinics across the world, the quality of published work to guide clinicians in the diagnosis and management is generally poor. Diagnosis should be based primarily on clinical signs supported by results of pathologic and radiologic investigations. Although the gold standard comes from the histologic and microbiological examination of bone, clinicians should be aware of the problems of sampling error. This lack of standardization of diagnostic criteria and of consensus on the choice of outcome measures poses further difficulties when seeking evidence to support management decisions. Experts have traditionally recommended surgical removal of infected bone but available evidence suggests that in many cases (excepting those in whom immediate surgery is required to save life or limb) a nonsurgical approach to management of osteomyelitis may be effective for many, if not most, patients with osteomyelitis of the diabetic foot. The benefits and limitations of both approaches need, however, to be established in prospective trials so that appropriate therapy can be offered to appropriate patients at the appropriate time, with the patients' views taken fully into account.

Screening for Osteomyelitis Using Thermography in Patients with Diabetic Foot

One of the most serious complications of diabetic foot (DF) is osteomyelitis, and early detection is important. To assess the validity of thermography to screen for osteomyelitis, we investigated thermographic findings in patients with both DF and osteomyelitis. The subjects were 18 diabetic patients with 20 occurrences of DF who visited a dermatology department at a hospital in Tokyo and underwent evaluation by magnetic resonance imaging (MRI) and thermography between June 2010 and July 2012. Osteomyelitis was identified by MRI. Thermographs were taken of the wounds and legs after bed rest of more than 15 minutes. Two wound management researchers evaluated the range of increased skin temperature. There were three types of distribution of increased skin temperature: the periwound, ankle, and knee patterns. Fisher’s exact test revealed that the ankle pattern was significantly more common in the group with osteomyelitis than in the group without osteomyelitis (P=0.011). The positive predictive value was 100%, and the negative predictive value was 71.4%. Our results suggest that an area of increased skin temperature extending to the ankle can be a sign of osteomyelitis. Thermography might therefore be useful for screening for osteomyelitis in patients with DF.

Incidence and predictors of hospitalization for bacterial infection in community-based patients with type 2 diabetes: the fremantle diabetes study

Background

The few studies that have examined the relationship between diabetes and bacterial infections have utilized administrative databases and/or have had limited/incomplete data including recognized infection risk factors. The aim of this study was to determine the incidence and associates of bacterial infection severe enough to require hospitalization in well-characterized community-based patients with type 2 diabetes.

Methods and Findings

We studied a cohort of 1,294 patients (mean±SD age 64.1±11.3 years) from the longitudinal observational Fremantle Diabetes Study Phase I (FDS1) and 5,156 age-, gender- and zip-code-matched non-diabetic controls. The main outcome measure was incident hospitalization for bacterial infection as principal diagnosis between 1993 and 2010. We also examined differences in statin use in 52 FDS1 pairs hospitalized with pneumonia (cases) or a contemporaneous non-infection-related cause (controls). During 12.0±5.4 years of follow-up, 251 (19.4%) patients were hospitalized on 368 occasions for infection (23.7/1,000 patient-years). This was more than double the rate in matched controls (incident rate ratio (IRR) (95% CI), 2.13 (1.88–2.42), P<0.001). IRRs for pneumonia, cellulitis, and septicemia/bacteremia were 1.86 (1.55–2.21), 2.45 (1.92–3.12), and 2.08 (1.41–3.04), respectively (P<0.001). Among the diabetic patients, older age, male sex, prior recent infection-related hospitalization, obesity, albuminuria, retinopathy and Aboriginal ethnicity were baseline variables independently associated with risk of first hospitalization with any infection (P≤0.005). After adjustment for these variables, baseline statin treatment was not significant (hazard ratio (95% CI), 0.70 (0.39–1.25), P = 0.22). Statin use at hospitalization for pneumonia among the case-control pairs was similar (23.1% vs. 13.5%, P = 0.27).

Conclusions

The risk of severe infection is increased among type 2 diabetic patients and is not reduced by statin therapy. There are a number of other easily-accessible sociodemographic and clinical variables that could be used to optimize infection-related education, prevention and management in type 2 diabetes.

Super-oxidized solution (Dermacyn Wound Care) as adjuvant treatment in the postoperative management of complicated diabetic foot osteomyelitis: preliminary experience in a specialized department

Surgery is usually used to treat diabetic foot osteomyelitis (DFO), whether primarily or in cases in which antibiotics are not able to control infection. In many cases, the bone is only partially removed, which means that residual infection remains in the bone margins, and the wound is left open to heal by secondary intent. The use of culture-guided postoperative antibiotic treatment and adequate management of the wound must be addressed. No trials exist dealing with local treatment in the postoperative management of these cases of complicated DFO. We decided to test a super-oxidized solution, Dermacyn Wound Care (DWC; Oculus Innovative Sciences Netherlands BV, Sittard, Netherlands) to obtain preliminary experience in patients in whom infected bone remained in the surgical wounds. Our hypothesis was that DWC could be useful to control infection in the residual infected bone and surrounding soft tissues and would thus facilitate healing. Fourteen consecutive patients who underwent conservative surgery for DFO, in whom clean bone margins could not be assured, were treated in the postoperative period with DWC. Eleven cases were located in the forefoot, 6 on the first ray and the rest in lesser toes, 1 in the Lisfranc joint, and 2 on the calcaneus. No side effects appeared during treatment. Neither allergies nor skin dermatitis were found. Limb salvage was successfully achieved in 100% of the cases. Healing was achieved in a median period of 6.8 weeks.

Gram-Negative Diabetic Foot Osteomyelitis

Osteomyelitis frequently complicates infections in the feet of patients with diabetes. Gram-positive cocci, especially Staphylococcus aureus, are the most commonly isolated pathogens, but gram-negative bacteria also cause some cases of diabetic foot osteomyelitis (DFO). These gram-negatives require different antibiotic regimens than those commonly directed at gram-positives. There are, however, few data on factors related to their presence and how they influence the clinical picture. We conducted a retrospective study to determine the variables associated with the isolation of gram-negative bacteria from bone samples in cases of DFO and the clinical presentation of these infections. Among 341 cases of DFO, 150 had a gram-negative isolate (alone or combined with a gram-positive isolate) comprising 44.0% of all patients and 50.8% of those with a positive bone culture. Compared with gram-positive infections, wounds with gram-negative organisms more often had a fetid odor, necrotic tissue, signs of soft tissue infection accompanying osteomyelitis, and clinically severe infection. By multivariate analysis, the predictive variables related to an increased likelihood of isolating gram-negatives from bone samples were glycated hemoglobin <7% (odds ratio [OR] = 2.0, 95% confidence interval [CI] = 1.1-3.5) and a wound caused by traumatic injury (OR = 2.0, 95% CI = 1.0-3.9). Overall, patients whose bone samples contained gram-negatives had a statistically significantly higher prevalence of leukocytosis and higher white blood cell counts than those without gram-negatives. In conclusion, gram-negative organisms were isolated in nearly half of our cases of DFO and were associated with more severe infections, higher white blood cell counts, lower glycated hemoglobin levels, and wounds of traumatic etiology.

Influence of osteomyelitis location in the foot of diabetic patients with transtibial amputation

BACKGROUND

To evaluate the prevalence of osteomyelitis in different areas of the foot and the possible correlation between localization and outcome of major amputation.

METHODS

From January 2008 to December 2010, a total of 350 diabetic patients were admitted to our diabetic foot unit for the surgical treatment of osteomyelitis. Osteomyelitis was diagnosed when both the probe-to-bone maneuver and plain radiography were positive. In all of these patients, osteomyelitis was confirmed by histological examination.

RESULTS

Osteomyelitis was localized to the forefoot in 300 (85.7%) patients, to the midfoot in 27 (7.7%) patients, and to the hindfoot in the remaining 23 (6.75) patients. On average, foot lesions had developed 6.6 ± 5.6 months before admission to our unit. Transtibial amputation was performed in 1 (0.33%) patient with forefoot osteomyelitis, in 5 (18.5%) patients with midfoot osteomyelitis, and in 12 (52.2%) patients with osteomyelitis of the heel (χ(2) = 128.4, P < .001). Multivariate analysis showed the independent role that osteomyelitis in the heel region had in major amputation outcome (odds ratio 15.3; P < .001; confidence interval, 17.4-5336.0), dialysis treatment (odds ratio 6.3; P = .012; confidence interval, 2.5-1667.2), and leukocyte count greater than 10(3) mm(3) (odds ratio 2.25; P = .036; confidence interval, 1.1-76.6).

CONCLUSIONS

We found a higher rate of transtibial amputation when osteomyelitis involved the heel instead of the midfoot or forefoot in diabetic patients.

LEVEL OF EVIDENCE

Level III, retrospective comparative series.

Does osteomyelitis in the feet of patients with diabetes really recur after surgical treatment? Natural history of a surgical series

AIMS/HYPOTHESIS

The aim of this study was to determine the rate of recurrence, reulceration and new episodes of osteomyelitis and the duration of postoperative antibiotic treatment in a prospective cohort of patients with diabetes who underwent conservative surgery for osteomyelitis.

METHODS

The prospective cohort included patients with diabetes and a definitive diagnosis of osteomyelitis who were admitted to the Diabetic Foot Unit (Surgery Department, La Paloma Hospital, Las Palmas de Gran Canaria, Spain) and underwent surgical treatment from 1 November 2007 to 30 May 2010.

RESULTS

Eighty-one patients were operated on for osteomyelitis during the study period. Seven patients were lost to follow-up at different stages of the study. The median duration of follow-up was 101.8 weeks (quartile 1 = 56.6, quartile 3 = 126.7). Forty-eight patients (59.3%) underwent conservative surgery, 32 (39.5%) had minor amputations and there was one (1.2%) major amputation. Twenty patients (24.7%) required reoperation because of persistent infection. Postoperative antibiotic treatment over a median period of 36 days was provided. Wound healing was achieved by secondary intention for a median of 8 weeks. Sixty-five patients were available for follow-up after healing. The percentage of recurrence, reulceration, and new episodes of osteomyelitis was 4.6% (3/65), 43% (28/65) and 16.9% (11/65), respectively. Mortality during follow-up (excluding in-hospital deaths and patients lost to follow-up) was 13% (9/69).

CONCLUSION

A low rate of recurrence of osteomyelitis after surgical treatment for osteomyelitis was achieved. Despite new episodes, our approach to managing this cohort of patients with diabetes and foot osteomyelitis achieved 98.8% limb salvage.

Clinical–Pathological Characterization of Diabetic Foot Infections

The present study has 3 aims: ( a) to characterize the clinical and pathological features of diabetic foot infections, ( b) to show the range of clinical presentations of moderate infections, and ( c) to analyze the different behavior of diabetic foot osteomyelitis regarding to its clinical presentation. A definitive diagnosis of the type of infection was made based on intraoperative findings and histopathology. Diabetic foot infections were classified into 2 types: soft tissue and bone infections. Mild infections were always superficial. Severe infections included 75% of necrotizing soft tissue infections. Moderate infections showed ample range of clinical presentations. Eighty-one patients presented osteomyelitis. Osteomyelitis was further classified as follows: osteomyelitis without ischemia and without soft tissue involvement (class 1), osteomyelitis with ischemia without soft tissue involvement (class 2), osteomyelitis with soft tissue involvement (class 3), and osteomyelitis with ischemia and soft tissue involvement (class 4). Forty-eight patients (59.3%) with osteomyelitis underwent conservative surgery, 32 (39.5%) had minor amputations including 9 open transmetatarsal amputations, and there was 1 (1.2%) major amputation. The characterization of osteomyelitis into 4 classes showed a statistically significant trend toward increased severity and increased amputation rate and mortality. In conclusion, the clinical presentation of foot infections in diabetic patients is very heterogeneous and can be classified into soft tissue infections (cellulitis, superficial and deep abscesses, and necrotizing soft tissue infections) and osteomyelitis, which was the most frequent type of infection found in the author’s series. Their division into 4 classes showed a statistically significant trend toward increased severity, amputation rate, and mortality. The diagnosis of deep soft tissue infections associated with osteomyelitis may be difficult to achieve before surgery.

Evidences and Controversies About Recurrence of Diabetic Foot Osteomyelitis

Recurrence is one of the most worrying issues when dealing with diabetic foot osteomyelitis (DFO). In accordance with expert opinion in other areas of bone infection, it is accepted that very late relapse of apparently successfully treated osteomyelitis is not uncommon. However, the physiopathology of infections in large bones secondary to hematogenous osteomyelitis, infected prostheses, and open fractures is quite different from what is seen in the feet of patients with diabetes. The anatomy of the bones, the mechanism of infection and alterations in host defenses that are frequently seen in patients with diabetes may condition the onset, clinical course, and outcomes. Apparent eradication, disappearance of inflammatory signs, wound healing, bone healing based on image studies, and no recurrences during follow-up are common terms used for defining the success of therapy for DFO. Failure of initial surgical treatment, readmission to hospital, and new episodes of infection at the same or a contiguous site are considered as recurrence of osteomyelitis. Theoretically, bacteria living in the bone could be the source of clinical recurrence, but is it possible to obtain complete healing while bacteria remain alive in the bone in the feet of patients with diabetes? Can these bacteria grow and spread from the bone to the skin after years of healing? In the author’s opinion, this type of long-term recurrence of DFO has not been well documented in the medical literature. It is the aim of this illustrated guide to review the evidence and controversies regarding the recurrence of DFO.

Statistical reliability of bone biopsy for the diagnosis of diabetic foot osteomyelitis

Bone biopsy is often referred to as the reference standard for the diagnosis of diabetic foot osteomyelitis (OM), and it also serves as an important interventional tool with respect to diabetic foot infections and limb salvage. However, the phrase bone biopsy lacks a standardized definition, and the statistical reliability of the pathologic diagnosis has not been previously examined. The objective of the present study was to quantify the reliability of the histopathologic analysis of bone with respect to the diagnosis of diabetic foot OM. Four pathologists, kept unaware of the previous pathology reports and specific patient clinical characteristics, retrospectively reviewed 39 consecutive tissue specimens and were informed only that it was "a specimen of bone taken from a diabetic foot to evaluate for OM." As a primary outcome measure, the pathologists were asked to make 1 of 3 possible diagnoses: (1) no evidence of OM, (2) no definitive findings of OM, but cannot rule it out, or (3) findings consistent with OM. There was complete agreement among all 4 pathologists with respect to the primary diagnosis in 13 (33.33%) of the 39 specimens, with a corresponding kappa coefficient of 0.31. A situation of clinically significant disagreement, or in which at least 1 pathologist diagnosed "no evidence of OM," but at least 1 other pathologist diagnosed "findings consistent with OM," occurred in 16 (41.03%) of the specimens. These results indicate agreement below the level of a "reference standard" and emphasize the need for a more comprehensive diagnostic protocol for diabetic foot OM.

The treatment of diabetic foot infections

Successful treatment of infection in the feet of patients with diabetes mellitus remains a challenge. Although the diagnosis of infection remains a clinical decision, presentation in feet rendered insensate from diabetic neuropathy plus co-existing vascular insufficiency means presentation is often atypical. Wounds frequently yield polymicrobial growth and differentiating commensal from pathogenic organisms can be difficult; isolates from diabetic foot wounds are often multidrug resistant. Affected patients often have many other co-morbidities, which not only affect the choice of appropriate antimicrobial regimen but also impede healing. Further, much contention surrounds the management of osteomyelitis, with the merits and role of surgery still undecided. In this review we briefly consider the epidemiology and pathogenesis of diabetic foot disease, before discussing emerging best microbiological practice and how this fits with the multidisciplinary approach required to tackle this difficult clinical problem.

Treatment of Diabetic Foot Osteomyelitis: A Surgical Critique

Osteomyelitis is one of the most frequent infections of the diabetic foot accounting for 10-15% of mild infections and almost 50% of severe infections. The definitive diagnosis of foot osteomyelitis requires obtaining bone samples for microbiological and histopathological studies. The treatment of osteomyelitis of the foot in diabetic patients continues to be debated. Until recently, most experts considered that the standard treatment for diabetic foot osteomyelitis should be the surgical removal of infected bone. Recent data suggest that antibiotic treatment can achieve an apparent remission of osteomyelitis though it is difficult to identify patients for this approach. One of the main arguments used to justify the solely antibiotic treatment of osteomyelitis is the alteration of foot biomechanics produced as a consequence of surgery. Conservative surgery combined with antibiotics is an attractive option in treating diabetic foot osteomyelitis because it may reduce the changes in the biomechanics of the foot and minimize the duration of antibiotic therapy. It is currently accepted that the combination of antibiotics with surgical removal of the infected bone may cure the majority of diabetic foot osteomyelitis. Recent literature emphasizes the role of antibiotics in the management of foot infections while little effort is dedicated to reviewing the surgical treatment of this challenging diabetic complication, apart from amputation. More research, including studies of adjunctive therapies in cases of bone infection in the feet of diabetic patients is required.