The treatment of diabetic foot infections

Concomitants of Diabetic Foot Ulcer - A Review

BACKGROUND

Diabetes mellitus leading to foot ulcer is a serious complication, and it is considered a global epidemic. Neuropathyand high blood glucose levels are the primary causes of foot ulcers. Fifteen percent of people with diabetes develop foot ulcers, and these foot disorders are the main cause of lower extremity amputation among such patients.

INTRODUCTION

Complications of diabetic foot, affecting the lower extremities are common and quite complex and life-threatening. This review focuses on the life-threatening factors associated with diabetic foot ulcers and also the diagnosing and preventive measures. Neuropathy assessment and the range of foot ulcers were accurately examined.

CONCLUSION

Novel therapies focusing on the vascularity of the lower limbs, infection control, and ischemic control are being developed to mainly treat nonhealing ulcers.

Development of predictive nomograms for clinical use to quantify the risk of isolating resistance prone organisms in patients with infected foot ulcers

Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA) have been considered prevalent pathogens in foot infections. However, whether empiric therapy directed against these organisms is necessary, and in whom to consider treatment, is rather unclear. The aim of this study was to develop predictive algorithms for forecasting the probability of isolating these organisms in the infected wounds of patients in a population where the prevalence of resistant pathogens is low. This was a retrospective study of regression model-based risk factor analysis that included 140 patients who presented with infected, culture positive foot ulcers to two urban hospitals. A total of 307 bacteria were identified, most frequently MRSA (11.1%). P. aeruginosa prevalence was 6.5%. In the multivariable analysis, amputation (odds ratio (OR) 5.75, 95% confidence interval (CI) 1.48-27.63), renal disease (OR 5.46, 95% CI 1.43-25.16) and gangrene (OR 2.78, 95% CI 0.82-9.59) were identified as risk factors associated with higher while diabetes (OR 0.07, 95% CI 0.01-0.34) and Infectious Diseases Society of America infection severity >3 (OR 0.18, 95% CI 0.03-0.65) were associated with lower odds of P. aeruginosa isolation (C statistic 0.81). Similar analysis for MRSA showed that amputation was associated with significantly lower (OR 0.29, 95% CI 0.09-0.79) risk, while history of MRSA infection (OR 5.63, 95% CI 1.56-20.63) and osteomyelitis (OR 2.523, 95% CI 1.00-6.79) was associated with higher odds of isolation (C statistic 0.69). We developed two predictive nomograms with reasonable to strong ability to discriminate between patients who were likely of being infected with P. aeruginosa or MRSA and those who were not. These analyses confirm the association of some, but also question the significance of other frequently described risk factors in predicting the isolation of these organisms.

Modulation of plantar pressure and gastrocnemius activity during gait using electrical stimulation of the tibialis anterior in healthy adults

High plantar flexor moment during the stance phase is known to cause high plantar pressure under the forefoot; however, the effects on plantar pressure due to a change of gastrocnemius medialis (GM) activity during gait, have not been investigated to date. Reciprocal inhibition is one of the effects of electrical stimulation (ES), and is the automatic antagonist alpha motor neuron inhibition which is evoked by excitation of the agonist muscle. The aim of this study was to investigate the influences of ES of the tibialis anterior (TA) on plantar pressure and the GM activity during gait in healthy adults. ES was applied to the TAs of twenty healthy male adults for 30 minutes at the level of intensity that causes a full range of dorsiflexion in the ankle (frequency; 50 Hz, on-time; 10 sec, off-time; 10 sec). Subjects walked 10 meters before and after ES, and we measured the peak plantar pressure (PP), pressure time integral (PTI), and gait parameters by using an F-scan system. The percentage of integrated electromyogram (%IEMG), active time, onset time, peak time, and cessation time of TA and GM were calculated. PP and PTI under the forefoot, rear foot, and total plantar surface significantly decreased after the application of ES. Meanwhile, changes of gait parameters were not observed. %IEMG and the active time of both muscles did not change; however, onset time and peak time of GM became significantly delayed. ES application to the TA delayed the timing of onset and peak in the GM, and caused the decrease of plantar pressure during gait. The present results suggest that ES to the TA could become a new method for the control of plantar pressure via modulation of GM activity during gait.

Liposome Entrapment of Bacteriophages Improves Wound Healing in a Diabetic Mouse MRSA Infection

Diabetic populations are more prone to developing wound infections which results in poor and delayed wound healing. Infection with drug resistant organisms further worsen the situation, driving searches for alternative treatment approaches such as phage therapy. Major drawback of phage therapy, however, is low phage persistence in situ, suggesting further refinement of the approach. In the present work we address this issue by employing liposomes as delivery vehicles. A liposome entrapped phage cocktail was evaluated for its ability to resolve a Staphylococcus aureus-induced diabetic excission wound infection. Two characterized S. aureus specific lytic phages, MR-5 and MR-10 alone, in combination (cocktail), or entrapped in liposomes (versus as free phages) were assesed for their therapeutic efficacy in resolving diabetic wound infection. Mice treated with free phage cocktail showed significant reduction in wound bioburden, greater wound contraction and faster tissue healing than with free monophage therapy. However, to further enhance the availability of viable phages the encapsulation of phage cocktail in the liposomes was done. Results of in vitro stability studies and in vivo phage titer determination, suggests that liposomal entrapment of phage cocktail can lead to better phage persistence at the wound site. A 2 log increase in phage titre, however, was observed at the wound site with liposome entrapped as compared to the free phage cocktail, and this was associaed with increased rates of infection resolution and wound healing. Entrapment of phage cocktails within liposomes thus could represent an attractive approach for treatment of bacterial infections, not responding to antibiotis as increased phage persistence in vitro and in vivo at the wound site was observed.

Staphylococcus aureus-dependent septic arthritis in murine knee joints: local immune response and beneficial effects of vaccination

Staphylococcus aureus is the major cause of human septic arthritis and osteomyelitis, which deserve special attention due to their rapid evolution and resistance to treatment. The progression of the disease depends on both bacterial presence in situ and uncontrolled disruptive immune response, which is responsible for chronic disease. Articular and bone infections are often the result of blood bacteremia, with the knees and hips being the most frequently infected joints showing the worst clinical outcome. We report the development of a hematogenous model of septic arthritis in murine knees, which progresses from an acute to a chronic phase, similarly to what occurs in humans. Characterization of the local and systemic inflammatory and immune responses following bacterial infection brought to light specific signatures of disease. Immunization of mice with the vaccine formulation we have recently described (4C-Staph), induced a strong antibody response and specific CD4+ effector memory T cells, and resulted in reduced bacterial load in the knee joints, a milder general inflammatory state and protection against bacterial-mediated cellular toxicity. Possible correlates of protection are finally proposed, which might contribute to the development of an effective vaccine for human use.

Influence of wound scores and microbiology on the outcome of the diabetic foot syndrome

AIMS

To establish if the microbiology and the TEXAS, PEDIS and Wagner wound classifications of the diabetic foot syndrome (DFS) predict amputation.

METHODS

Prospective cohort study of 250 patients with DFS from 2009 to 2013. Tissue samples for culture were obtained and wound classification scores were recorded at admission.

RESULTS

Infection was monomicrobial in 131 patients (52%). Staphylococcus aureus was the most frequent pathogen (76 patients, 30%); being methicillin-resistant S. aureus in 26% (20/76) Escherichia coli and Enterobacter faecalis were 2nd and 3rd most frequent pathogens. Two hundred nine patients (85%) needed amputation being major in 25 patients (10%). The three wound scales associated minor amputation but did not predict this outcome. Predictors of minor amputation in the multivariate analysis were the presence of osteomyelitis, the location of the wound in the forefoot and of major amputation elevated C reactive proteine (CRP) levels. A low ankle-brachial index (ABI) predicted major amputation in the follow-up. Overall, 74% of gram-positives were sensitive to quinolones and 98% to vancomycin and 90% of gram-negatives to cefotaxime and 95% to carbapenems.

CONCLUSIONS

The presence of osteomyelitis and the location of the wound in the forefoot predict minor amputation and elevated CRP levels predict major amputation. In the follow-up a low ABI predicts major amputation.

Diagnosing diabetic foot osteomyelitis in patients without signs of soft tissue infection by coupling hybrid 67Ga SPECT/CT with bedside percutaneous bone puncture

OBJECTIVE

Successful treatment of osteomyelitis is more likely with accurate diagnosis and identification of the causative pathogens. This typically requires obtaining a specimen of bone, usually by image-guided biopsy. We sought to develop a simpler bedside method for definitively diagnosing osteomyelitis.

RESEARCH DESIGN AND METHODS

Over 2 years, we enrolled consecutive patients presenting to our diabetic foot clinic with a foot ulcer and clinically suspected osteomyelitis but without soft tissue infection. Each underwent hybrid (67)Ga single-photon emission computed tomography and X-ray computed tomography (SPECT/CT) imaging; those with a positive scan underwent bedside percutaneous bone puncture. Patients with a positive bone culture received culture-guided antibiotic therapy. Patients with negative (67)Ga SPECT/CT imaging or with positive imaging but negative bone culture were not treated with antibiotics. All patients were followed up for ≥ 1 year.

RESULTS

Among 55 patients who underwent (67)Ga SPECT/CT imaging, 13 had negative results and all of their foot ulcers resolved without antibiotic therapy. Among 42 with positive imaging, 2 were excluded (for recent antibiotic therapy) and 40 had bone punctures (3 punctured twice): 19 had negative results, 3 of which were likely false negatives, and 24 had positive results (all gram-positive cocci). At follow-up, 3 patients had died, 3 had undergone amputation, and 47 had no evidence of foot infection. The sensitivity and specificity of this combined method were 88.0 and 93.6%, respectively, and the positive and negative predictive values were 91.7 and 90.7%, respectively.

CONCLUSIONS

Coupling of (67)Ga SPECT/CT imaging and bedside percutaneous bone puncture appears to be accurate and safe for diagnosing diabetic foot osteomyelitis in patients without signs of soft tissue infection, obviating the need for antibiotic treatment in 55% of suspected cases.

Diabetic foot infections: the role of microbiology and antibiotic treatment

Diabetes mellitus is a major risk factor for the development of foot infections. Among the risk factors that contribute to the development of diabetic foot infections are local neuropathy, vascular changes and depressed local host defenses. The microbiology of these infections is often complex and can be polymicrobial. Treatment of these infections depends on the severity and extent of infection. Treatment should involve a multi-disciplinary team approach involving surgeons and infectious disease specialists. The current recommendations for treatment are primarily based on expert opinion and consensus rather than clinical trials. No single agent or combination of agents has been shown to be superior to others. The aim of this review is to provide valid options of therapy, especially with regard to newer agents that are currently available for treatment of both soft tissue infections and osteomyelitis.

Four-stage regimen for operative treatment of diabetic foot ulcer with deformity - a results of 300 patients

BACKGROUND

An operative four-stage regimen (stage 1, debridement; stage 2, closure; stage 3, unloading; stage 4, correction) for operative treatment of diabetic foot ulcer with deformity, and first clinical results are introduced.

METHODS AND RESULTS

335 patients entered stage 1 between 01/09/2006 and 31/08/2010. Stage 1: In 189 cases (56%), one debridement resulted in sterile postoperative specimens. Stage 2: 210 cases (63%) sustained secondary closure, 97 (29%) local shifted skin graft, and 20 (6%) functional amputation. Stage 3: 304 (90%) finished stage 3, 14 (4%) presented with recurrent ulcer. Stage 4: In 185 cases (55%), correction arthrodeses were performed successfully.

FOLLOW-UP

300 (90%) completed follow-up at 26months on average (12-48months). Recurrent ulcer was registered in 46 (15%). Overall amputation rate was 14%, the majority at digital or midfoot level. Four cases (1%) required a below-knee amputation.

CONCLUSIONS

The management of diabetic foot ulcer combined with deformity with the introduced regimen showed low major amputation rate and low recurrent ulcer rate compared with the literature.

Infections in patients with diabetes mellitus: A review of pathogenesis

In general, infectious diseases are more frequent and/or serious in patients with diabetes mellitus, which potentially increases their morbimortality. The greater frequency of infections in diabetic patients is caused by the hyperglycemic environment that favors immune dysfunction (e.g., damage to the neutrophil function, depression of the antioxidant system, and humoral immunity), micro- and macro-angiopathies, neuropathy, decrease in the antibacterial activity of urine, gastrointestinal and urinary dysmotility, and greater number of medical interventions in these patients. The infections affect all organs and systems. Some of these problems are seen mostly in diabetic people, such as foot infections, malignant external otitis, rhinocerebral mucormycosis, and gangrenous cholecystitis. In addition to the increased morbidity, infectious processes may be the first manifestation of diabetes mellitus or the precipitating factors for complications inherent to the disease, such as diabetic ketoacidosis and hypoglycemia. Immunization with anti-pneumococcal and influenza vaccines is recommended to reduce hospitalizations, deaths, and medical expenses.