Local Antibiotic Delivery Systems: Current and Future Applications for Diabetic Foot Infections

The Efficacy of Local Antibiotic Delivery Systems Therapy in the Management of Diabetic Foot Osteomyelitis: A Systematic Review and Meta-Analysis

PURPOSE

We aim to evaluate the efficacy of local antibiotic delivery systems in patients with diabetic foot osteomyelitis (DFO).

METHODS

The Web of Science, PubMed, and Embase databases were searched for relevant publications until March 2024. All studies evaluating the efficacy of local antibiotic delivery systems in patients with DFO were included. We calculated pooled risk ratio (RR) with 95% CIs for binary outcomes and mean difference (MD) for continuous outcomes. The Cochrane's risk of bias tool and methodological index for non-randomized studies (MINORS) assessment were used to evaluate the quality of studies.

RESULTS

A total of 9 studies with 491 patients were included in this analysis. The overall healing rate in antibiotic group was 0.85 (95% CI: 0.67, 0.97). Healing rates were significantly higher in the antibiotic group compared to the control group (RR: 1.18, 95% CI: 1.01, 1.38). Furthermore, recurrence rates and amputation rates have no significantly difference between the antibiotic group and the control group (RR: 0.30, 95% CI: 0.04, 2.12 and RR: 0.22, 95% CI:0.03, 1.91), along with no significantly difference in healing time and hospital stays(MD: -7.87, 95% CI: -20.81, 5.07 and MD:-2.33, 95% CI:-5.17, 0.50). No obvious publication bias was observed in the funnel plot (Egger's test, P = .99).

CONCLUSIONS

Our meta-analysis found that diabetic foot osteomyelitis patients treated with local antibiotic delivery systems had better healing rates than the control group. However, no significant differences were found in healing time, recurrence, hospital stays, or amputation rates. Larger randomized controlled trials are necessary in the future.

Topical Administration of Teucrium polium on Diabetic Foot Ulcers Accelerates Healing: A Placebo-Controlled Randomized Clinical Study

Diabetic foot ulcer is one of the most devastating complications of uncontrolled diabetes. Although there have been advances in the management of diabetic foot ulcers, still diabetic foot ulcers are a major cause of many amputations in diabetic patients. Teucrium polium (T. polium) is widely used by folk medicine practitioners in Iran for the treatment of diabetic ulcers.The present study was designed to evaluate the safety and efficacy of topical T. polium ointment besides the standard treatment in diabetic foot ulcers.A total of 70 diabetic patients with foot ulcers grade 1 or 2 according to Wagner's scale were enrolled in this study. Patients were randomly divided into two groups. Patients in both groups received standard treatment for diabetic foot ulcers. In addition, group 1 received topical T. polium ointment, and group 2 received topical placebo ointment for 4 weeks. The T. polium and placebo ointments were rubbed twice daily two hours before the conventional dressing. The ulcer size, healing time, and laboratory tests were measured in both groups at baseline and end of the study after 4 weeks.Twenty-nine patients remained in the T. polium group and 26 in the placebo group until the end of the study. The mean surface area of ulcers was 3.52 ± 1.47 and 3.21 ± 1.67 cm2 in T. polium group and placebo group respectively at baseline which decrease to .717 ± .19 and 1.63 ± .72 cm2 respectively at the endpoint. The mean ulcer surface area was significantly lower in T. polium compared with the placebo group (p < .0001) at end of the study. Also, the number of patients that completely recovered in the T. polium group was significantly higher than the placebo group (p < .001) at the end of the study.The addition of topical T. polium ointment to standard treatment significantly improves the healing time of diabetic non-infected foot ulcers.

Conductive hydrogels based on tragacanth and silk fibroin containing dopamine functionalized carboxyl-capped aniline pentamer: Merging hemostasis, antibacterial, and anti-oxidant properties into a multifunctional hydrogel for burn wound healing

Hydrogels possessing both conductive characteristics and notable antibacterial and antioxidant properties hold considerable significance within the realm of wound healing and recovery. The object of current study is the development of conductive hydrogels with antibacterial and antioxidant properties, emphasizing their potential for effective wound healing, especially in treating third-degree burns. For this purpose, various conductive hydrogels are developed based on tragacanth and silk fibroin, with variable dopamine functionalized carboxyl-capped aniline pentamer (CAP@DA). The FTIR analysis confirms that the CAP powder was successfully synthesized and modified with DA. The results show that the incorporation of CAP@DA into hydrogels can increase the porosity and swellability of the hydrogels. Additionally, the mechanical and viscoelastic properties of the hydrogels are also improved. The release of vancomycin from the hydrogels is sustained over time, and the hydrogels are effective in inhibiting the growth of Methicillin-resistant Staphylococcus aureus (MRSA). In vitro cell studies of the hydrogels show that all hydrogels are biocompatible and support cell attachment. The hydrogels' tissue adhesiveness yielded a satisfactory hemostatic outcome in a rat-liver injury model. The third-degree burn was created on the dorsal back paravertebral region of the rats and then grafted with hydrogels. The burn was monitored for 3, 7, and 14 days to evaluate the efficacy of the hydrogel in promoting wound healing. The hydrogels revealed treatment effect, resulting in enhancements in wound closure, dermal collagen matrix production, new blood formation, and anti-inflammatory properties. Better results were obtained for hydrogel with increasing CAP@DA. In summary, the multifunctional conducive hydrogel, featuring potent antibacterial properties, markedly facilitated the wound regeneration process.

Development and evaluation of ciprofloxacin local controlled release materials based on molecularly imprinted polymers

The aim of this study was the molecular imprinting polymers (MIPs) assessment as a controlled release system of ciprofloxacin. The MIPs synthesis was performed by three different methods: emulsion, bulk, and co-precipitation. Lactic acid (LA) and methacrylic acid (MA) were used as functional monomers and ethylene glycol dimethacrylate as crosslinker. Also, nonimprinted polymers (NIPs) were synthesized. MIPs and NIPs were characterized by scanning electron microscopy, Fourier Transform Infrared Reflection, specific surface area, pore size, and release kinetics. Their efficiency against Staphylococcus aureus and Escherichia coli, and their cytotoxicity in dermal fibroblast cells were proven. Results show that MIPs are mesoporous materials with a pore size between 10 and 20 nm. A higher adsorption with the co-precipitation MIP with MA as a monomer was found. The release kinetics proved that a non-Fickian process occurred and that the co-precipitation MIP with LA presented the highest release rate (90.51 mg/L) in 8 h. The minimum inhibitory concentration was found between 0.031 and 0.016 mg/L for Staphylococcus aureus and between 0.004 and 0.031 mg/L for the Escherichia coli. No cytotoxicity in cellular cultures was found; also, cellular growth was favored. This study demonstrated that MIPs present promising properties for drug administration and their application in clinical practice.

Assessment of antibiotic release and antibacterial efficacy from pendant glutathione hydrogels using ex vivo porcine skin

Acute bacterial skin and skin structure infections (ABSSSIs) confer a substantial burden on the healthcare system. Local antibiotic delivery systems can provide controlled drug release directly to the site of infection to maximize efficacy and minimize systemic toxicity. The purpose of this study was to examine the antibacterial activity of antibiotic-loaded glutathione-conjugated poly(ethylene glycol) hydrogels (GSH-PEG) against ABSSSIs utilizing an ex vivo porcine dermal explant model. Vancomycin- or meropenem-loaded GSH-PEG hydrogels at 3 different dose levels were loaded over 1 h. Drug release was monitored in vitro under submerged conditions, by the Franz cell diffusion method, and ex vivo utilizing a porcine dermis model. Antibacterial activity was assessed ex vivo on porcine dermis explants inoculated with Staphylococcus aureus or Pseudomonas aeruginosa isolates treated with vancomycin- or meropenem-loaded GSH-PEG hydrogels, respectively. Histological assessment of the explants was conducted to evaluate tissue integrity and viability in the context of the experimental conditions. A dose-dependent release was observed from vancomycin and meropenem hydrogels, with in vitro Franz cell diffusion data closely representing ex vivo vancomycin release, but not high dose meropenem release. High dose vancomycin-loaded hydrogels resulted in a >3 log10 clearance against all S. aureus isolates at 48 h. High dose meropenem-loaded hydrogels achieved 6.5, 4, and 2 log10 reductions in CFU/ml against susceptible, intermediate, and resistant P. aeruginosa isolates, respectively. Our findings demonstrate the potential application of GSH-PEG hydrogels for flexible, local antibiotic delivery against bacterial skin infections.

Highly active nisin coated polycaprolactone electrospun fibers against both Staphylococcus aureus and Pseudomonas aeruginosa

In this study, a wound dressing of electrospun polycaprolactone (PCL) fibers incorporating the antimicrobial peptide (AMP) nisin was fabricated. Nisin was physically adsorbed to the PCL fibers and tested for antibacterial activity against both Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa). The PCL fibers had an average diameter of 1.16 μm ± 0.42 μm and no significant change in diameter occurred after nisin adsorption. X-ray photoelectron spectroscopy (XPS) analysis of the fibers detected nitrogen indicative of adsorbed nisin and the signal was used to quantify the levels of coverage on the fiber surfaces. In vitro nisin release studies showed a burst release profile with 80 % of the nisin being released from the fibers within 30 min. Air plasma pre-treatment of the PCL fibers to render them hydrophilic improved nisin loading and release. Antibacterial testing was performed using minimum inhibitory concentration (MIC) and surface attachment assays. The released nisin remained active against both Gram positive S. aureus and Gram negative P. aeruginosa, which has previously been difficult to achieve with single polymer fiber systems. Mammalian cell culture of the nisin coated fibers with L-929 mouse fibroblasts and human epidermal keratinocytes (HEKa) showed that the nisin did not have a significant effect on the biocompatibility of the PCL fibers. The results presented here demonstrate that the physical adsorption, which is a post-treatment, overcomes the potential limitations of harsh chemicals and fabrication conditions of electrospinning from organic solvents and provides a drug loading system having effective antibacterial properties in wound dressings.

Bioinspired 3D-printed scaffold embedding DDAB-nano ZnO/nanofibrous microspheres for regenerative diabetic wound healing

There is a constant demand for novel materials/biomedical devices to accelerate the healing of hard-to-heal wounds. Herein, an innovative 3D-printed bioinspired construct was developed as an antibacterial/regenerative scaffold for diabetic wound healing. Hyaluronic/chitosan (HA/CS) ink was used to fabricate a bilayer scaffold comprising a dense plain hydrogel layer topping an antibacterial/regenerative nanofibrous layer obtained by incorporating the hydrogel with polylactic acid nanofibrous microspheres (MS). These were embedded with nano ZnO (ZNP) or didecyldimethylammonium bromide (DDAB)-treated ZNP (D-ZNP) to generate the antibacterial/healing nano/micro hybrid biomaterials, Z-MS@scaffold and DZ-MS@scaffold. Plain and composite scaffolds incorporating blank MS (blank MS@scaffold) or MS-free ZNP@scaffold and D-ZNP@scaffold were used for comparison. 3D printed bilayer constructs with customizable porosity were obtained as verified by SEM. The DZ-MS@scaffold exhibited the largest total pore area as well as the highest water-uptake capacity andin vitroantibacterial activity. Treatment ofStaphylococcus aureus-infected full thickness diabetic wounds in rats indicated superiority of DZ-MS@scaffold as evidenced by multiple assessments. The scaffold afforded 95% wound-closure, infection suppression, effective regulation of healing-associated biomarkers as well as regeneration of skin structure in 14 d. On the other hand, healing of non-diabetic acute wounds was effectively accelerated by the simpler less porous Z-MS@scaffold. Information is provided for the first-time on the 3D printing of nanofibrous scaffolds using non-electrospun injectable bioactive nano/micro particulate constructs, an innovative ZNP-functionalized 3D-printed formulation and the distinct bioactivity of D-ZNP as a powerful antibacterial/wound healing promotor. In addition, findings underscored the crucial role of nanofibrous-MS carrier in enhancing the physicochemical, antibacterial, and wound regenerative properties of DDAB-nano ZnO. In conclusion, innovative 3D-printed DZ-MS@scaffold merging the MS-boosted multiple functionalities of ZNP and DDAB, the structural characteristics of nanofibrous MS in addition to those of the 3D-printed bilayer scaffold, provide a versatile bioactive material platform for diabetic wound healing and other biomedical applications.

Diabetic Foot Ulcers and Their Surgical Management: Our Experience at Hayatabad Medical Complex, Peshawar

BACKGROUND

Surgeons face a therapeutic challenge while treating diabetic foot ulcers (DFUs), particularly in underdeveloped nations with limited healthcare resources and a high proportion of patients who arrive at medical institutions with advanced foot ulcers.

OBJECTIVE

To assess the effectiveness of treatment in patients with DFUs and to demonstrate how early surgical intervention and appropriate bedside medical care can improve results.

MATERIAL AND METHODS

This prospective study was carried out at Hayatabad Medical Complex, Peshawar, Pakistan, to assess how DFUs changed over a period between November 2021 and December 2022 at the wards and at the outpatient department of endocrinology and general surgery. A diabetic patient's foot is first screened for ulceration in the endocrinology department, and only those with active ulcers are referred to the surgical department.

RESULTS

According to the Wagner classification, there were six (13.6%) cases in grade I, 11 (25%) in grade 2, 10 (22.7%) in grade 3, 13 (29.5%) in grade 4, and four (9%) in grade 5. Among comorbidities, a family history of diabetes mellitus was noted in 25 (56.8%) patients, followed by tobacco chewing and alcohol in 10 (22.7%) and hypertension in nine (20.4%) patients.

CONCLUSION

Diabetes foot ulceration is the most common reason for non-traumatic lower limb amputation in people with diabetes mellitus and is a significant cause of morbidity and mortality.

What’s old is new again: Insights into diabetic foot microbiome

Diabetes is a chronic disease that is considered one of the most stubborn global health problems that continues to defy the efforts of scientists and physicians. The prevalence of diabetes in the global population continues to grow to alarming levels year after year, causing an increase in the incidence of diabetes complications and health care costs all over the world. One major complication of diabetes is the high susceptibility to infections especially in the lower limbs due to the immunocompromised state of diabetic patients, which is considered a definitive factor in all cases. Diabetic foot infections continue to be one of the most common infections in diabetic patients that are associated with a high risk of serious complications such as bone infection, limb amputations, and life-threatening systemic infections. In this review, we discussed the circumstances associated with the high risk of infection in diabetic patients as well as some of the most commonly isolated pathogens from diabetic foot infections and the related virulence behavior. In addition, we shed light on the different treatment strategies that aim at eradicating the infection.

Evaluation of Adjuvant Antibiotic Loaded Injectable Bio-Composite Material in Diabetic Foot Osteomyelitis and Charcot Foot Reconstruction

The management of diabetic foot osteomyelitis (DFO) is extremely challenging with high amputation rates reported alongside a five-year mortality risk of more than fifty percent. We describe our experience in using adjuvant antibiotic-loaded bio-composite material (Cerament) in the surgical management of DFO and infected Charcot foot reconstruction. We undertook a retrospective evaluation of 53 consecutive patients (54 feet) who underwent Gentamicin or Vancomycin-loaded Cerament application during surgery. The feet were categorised into two groups: Group 1, with infected ulcer and DFO, managed with radical debridement only (n = 17), and Group 2, requiring reconstruction surgery for infected and deformed Charcot foot. Group 2 was further subdivided into 2a, with feet previously cleared of infection and undergoing a single-stage reconstruction (n = 19), and 2b, with feet having an active infection managed with a two-stage reconstruction (n = 18). The mean age was 56 years (27-83) and 59% (31/53) were males. The mean BMI was 30.2 kg/m² (20.8-45.5). Foot ulcers were present in 69% (37/54) feet. At a mean follow-up of 30 months (12-98), there were two patients lost to follow up and the mortality rate was 11% (n = 5). The mean duration of post-operative systemic antibiotic administration was 20 days (4-42). Thirteen out of fifteen feet (87%) in group 1 achieved complete eradication of infection. There was a 100% primary ulcer resolution, 100% limb salvage and 76% bony union rate within Group 2. However, five patients, all in group 2, required reoperations due to problems with bone union. The use of antibiotic-loaded Cerament resulted in a high proportion of patients achieving infection clearance, functional limb salvage and decrease in the duration of postoperative antibiotic therapy. Larger, preferably randomised, studies are required to further validate these observations.

Diabetic Pedal Osteomyelitis and Its Treatment

Diabetes is a fast-growing chronic metabolic disorder that is widely associated with foot ulcers. The major challenge among these ulcers is wound infections, altered inflammatory responses, and a lack of angiogenesis that can complicate limb amputation. The foot, because of its architecture, becomes the part most prone to complications and the infection rate is higher mainly between the toes due to the humid nature. Therefore, the infection rate is significantly higher. Wound healing in diabetes is a dynamic process usually delayed due to poor immune function. Diabetes-related pedal neuropathy and perfusion disturbances can lead to a loss of sensation in the foot. This neuropathy can further be a risk factor for ulcer development due to repetitive mechanical stress that later might get infected by the invasion of microorganisms extending to the bone and causing an infection called pedal osteomyelitis. This review details the pathophysiology, the biomaterials aiding in the infection cure and regeneration of bone along with their limitations, as well as their future prospects.

Hybrid microneedle arrays for antibiotic and near-IR photothermal synergistic antimicrobial effect against Methicillin-Resistant Staphylococcus aureus

The rise of antibiotic-resistant skin and soft tissue infections (SSTIs) necessitates the development of novel treatments to improve the efficiency and delivery of antibiotics. The incorporation of photothermal agents such as plasmonic nanoparticles (NPs) improves the antibacterial efficiency of antibiotics through synergism with elevated temperatures. Hybrid microneedle (MN) arrays are promising local delivery platforms that enable co-therapy with therapeutic and photothermal agents. However, to-date, the majority of hybrid MNs have focused on the potential treatment of skin cancers, while suffering from the shortcoming of the intradermal release of photothermal agents. Here, we developed hybrid, two-layered MN arrays consisting of an outer water-soluble layer loaded with vancomycin (VAN) and an inner water-insoluble near-IR photothermal core. The photothermal core consists of flame-made plasmonic Au/SiO2 nanoaggregates and polymethylmethacrylate (PMMA). We analyzed the effect of the outer layer polymer, polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP), on MN morphology and performance. Hybrid MNs produced with 30 wt% PVA contain a highly drug-loaded outer shell allowing for the incorporation of VAN concentrations up to 100 mg g-1 and temperature increases up to 60 °C under near-IR irradiation while showing sufficient mechanical strength for skin insertion. Furthermore, we studied the combinatorial effect of VAN and heat on the growth inhibition of methicillin-resistant Staphylococcus aureus (MRSA) showing synergistic inhibition between VAN and heat above 55 °C for 10 min. Finally, we show that treatment with hybrid MN arrays can inhibit the growth of MRSA due to the synergistic interaction of heat with VAN reducing the bacterial survival by up to 80%. This proof-of-concept study demonstrates the potential of hybrid, two-layered MN arrays as a novel treatment option for MRSA-associated skin infections.

Improving the Management and Treatment of Diabetic Foot Infection: Challenges and Research Opportunities

Diabetic foot infection (DFI) management requires complex multidisciplinary care pathways with off-loading, debridement and targeted antibiotic treatment central to positive clinical outcomes. Local administration of topical treatments and advanced wound dressings are often used for more superficial infections, and in combination with systemic antibiotics for more advanced infections. In practice, the choice of such topical approaches, whether alone or as adjuncts, is rarely evidence-based, and there does not appear to be a single market leader. There are several reasons for this, including a lack of clear evidence-based guidelines on their efficacy and a paucity of robust clinical trials. Nonetheless, with a growing number of people living with diabetes, preventing the progression of chronic foot infections to amputation is critical. Topical agents may increasingly play a role, especially as they have potential to limit the use of systemic antibiotics in an environment of increasing antibiotic resistance. While a number of advanced dressings are currently marketed for DFI, here we review the literature describing promising future-focused approaches for topical treatment of DFI that may overcome some of the current hurdles. Specifically, we focus on antibiotic-impregnated biomaterials, novel antimicrobial peptides and photodynamic therapy.

Local Antibiotics in the Treatment of Diabetic Foot Infections: A Narrative Review

Along with the increasing global burden of diabetes, diabetic foot infections (DFI) and diabetic foot osteomyelitis (DFO) remain major challenges for patients and society. Despite progress in the development of prominent international guidelines, the optimal medical treatment for DFI and DFO remains unclear as to whether local antibiotics, that is, topical agents and local delivery systems, should be used alone or concomitant to conventional systemic antibiotics. To better inform clinicians in this evolving field, we performed a narrative review and summarized key relevant observational studies and clinical trials of non-prophylactic local antibiotics for the treatment of DFI and DFO, both alone and in combination with systemic antibiotics. We searched PubMed for studies published between January 2000 and October 2022, identified 388 potentially eligible records, and included 19 studies. Our findings highlight that evidence for adding local antibiotic delivery systems to standard DFO treatment remains limited. Furthermore, we found that so far, local antibiotic interventions have mainly targeted forefoot DFO, although there is marked variation in the design of the included studies. Suggestive evidence emerging from observational studies underscores that the addition of local agents to conventional systemic antibiotics might help to shorten the clinical healing time and overall recovery rates in infected diabetic foot ulcers, although the effectiveness of local antibiotics as a standalone approach remains overlooked. In conclusion, despite the heterogeneous body of evidence, the possibility that the addition of local antibiotics to conventional systemic treatment may improve outcomes in DFI and DFO cannot be ruled out. Antibiotic stewardship principles call for further research to elucidate the potential benefits of local antibiotics alone and in combination with conventional systemic antibiotics for the treatment of DFI and DFO.

An all-in-one CO gas therapy-based hydrogel dressing with sustained insulin release, anti-oxidative stress, antibacterial, and anti-inflammatory capabilities for infected diabetic wounds

To effectively treat diabetic wounds, the development of versatile medical dressings that can long-term regulate blood glucose and highly effective anti-oxidative stress, antibacterial and anti-inflammatory are critical. Here, an all-in-one CO gas-therapy-based versatile hydrogel dressing (ICOQF) was developed via the dynamic Schiff base reaction between the amino groups on quaternized chitosan (QCS) and the aldehyde groups on benzaldehyde-terminated F108 (F108-CHO) micelles. CORM-401 (an oxidant-sensitive CO-releasing molecules) was encapsulated in the hydrophobic core of F108-CHO micelles and insulin was loaded in the three-dimensional network structure of ICOQF. The dynamic Schiff base bonds not only endowed ICOQF with good tissue adhesion, injectability and self-healing, but also gave it sustained and controllable insulin release ability. In addition, ICOQF could quickly generate CO in inflamed wound tissue by consuming reactive oxygen species. The generated CO could effectively anti-oxidative stress by activating the expression of heme oxygenase; antibacterial by inducing the rupture of bacterial cell membranes and mitochondrial dysfunction and inhibiting the synthesis of adenosine triphosphate; and anti-inflammatory by inhibiting the proliferation of activated macrophages and promoting the polarization of the M1 phenotype to the M2 phenotype. Due to these outstanding properties, ICOQF significantly promoted the healing of STZ-induced MRSA-infected diabetic wounds accompanied by good biocompatibility. This study clearly shows that ICOQF is a versatile hydrogel dressing with great application potential for the management of diabetic wounds. STATEMENT OF SIGNIFICANCE: The development of some versatile hydrogel dressings that can not only provide a prolonged and controlled insulin release property but also utilize a non-antibiotic treatment modality for highly effective antibacterial, anti-inflammatory, and anti-oxidative stress effects is vital for the successful treatment of diabetic wounds. Herein, we developed an all-in-one CO gas-therapy-based versatile hydrogel dressing (ICOQF) with sustained and controllable insulin release abilities. Moreover, ICOQF could not only quickly release CO in the inflamed wound tissue by consumption of reactive oxygen species but also utilize the generated CO to highly effectively anti-oxidative stress, antibacterial, and anti-inflammatory. ICOQF therapy substantially promoted the healing of STZ-induced MRSA-infected diabetic wounds. Overall, this work provides a multifunctional hydrogel dressing for the management of diabetic wounds.

Biological Functions and Applications of Antimicrobial Peptides

Abstract:

Despite antimicrobial resistance, which is attributed to the misuse of broad-spectrum antibiotics, antibiotics can indiscriminately kill pathogenic and beneficial microorganisms. These events disrupt the delicate microbial balance in both humans and animals, leading to secondary infections and other negative effects. Antimicrobial peptides (AMPs) are functional natural biopolymers in plants and animals. Due to their excellent antimicrobial activities and absence of microbial resistance, AMPs have attracted enormous research attention. We reviewed the antibacterial, antifungal, antiviral, antiparasitic, as well as antitumor properties of AMPs and research progress on AMPs. In addition, we highlighted various recommendations and potential research areas for their progress and challenges in practical applications.

Overcoming the rising incidence and evolving mechanisms of antibiotic resistance by novel drug delivery approaches - An overview

Antimicrobial resistance is a normal evolutionary process for microorganisms. Antibiotics exerted accelerated selective pressure that hasten bacterial resistance through mutation, and acquisition external genes. These genes often carry multiple antibiotic resistant determinants allowing the recipient microbe an instant "super-bug" status. The extent of Antimicrobial Resistance (AMR) has reached a level of global crisis, existing antimicrobials are no long effective in treating infections caused by AMR pathogens. The great majority of clinically available antimicrobial agents are administered through oral and intra-venous routes. Overcoming antibacterial resistance by novel drug delivery approach offered new hopes, particularly in the treatment of AMR pathogens in sites less assessible through systemic circulation such as the lung and skin. In the current review, we will revisit the mechanism and incidence of important AMR pathogens. Finally, we will discuss novel drug delivery approaches including novel local antibiotic delivery systems, hybrid antibiotics, and nanoparticle-based antibiotic delivery systems.

Alternative Approaches for the Management of Diabetic Foot Ulcers

Diabetic foot ulcers (DFU) represent a growing public health problem. The emergence of multidrug-resistant (MDR) bacteria is a complication due to the difficulties in distinguishing between infection and colonization in DFU. Another problem lies in biofilm formation on the skin surface of DFU. Biofilm is an important pathophysiology step in DFU and may contribute to healing delays. Both MDR bacteria and biofilm producing microorganism create hostile conditions to antibiotic action that lead to chronicity of the wound, followed by infection and, in the worst scenario, lower limb amputation. In this context, alternative approaches to antibiotics for the management of DFU would be very welcome. In this review, we discuss current knowledge on biofilm in DFU and we focus on some new alternative solutions for the management of these wounds, such as antibiofilm approaches that could prevent the establishment of microbial biofilms and wound chronicity. These innovative therapeutic strategies could replace or complement the classical strategy for the management of DFU to improve the healing process.

Limited Treatment Options for Diabetic Wounds: Barriers to Clinical Translation Despite Therapeutic Success in Murine Models

Significance: Millions of people worldwide suffer from diabetes mellitus and its complications, including chronic diabetic wounds. To date, there are few widely successful clinical therapies specific to diabetic wounds beyond general wound care, despite the vast number of scientific discoveries in the pathogenesis of defective healing in diabetes. Recent Advances: In recent years, murine animal models of diabetes have enabled the investigation of many possible therapeutics for diabetic wound care. These include specific cell types, growth factors, cytokines, peptides, small molecules, plant extracts, microRNAs, extracellular vesicles, novel wound dressings, mechanical interventions, bioengineered materials, and more. Critical Issues: Despite many research discoveries, few have been translated from their success in murine models to clinical use in humans. This massive gap between bench discovery and bedside application begs the simple and critical question: what is still missing? The complexity and multiplicity of the diabetic wound makes it an immensely challenging therapeutic target, and this lopsided progress highlights the need for new methods to overcome the bench-to-bedside barrier. How can laboratory discoveries in animal models be effectively translated to novel clinical therapies for human patients? Future Directions: As research continues to decipher deficient healing in diabetes, new approaches and considerations are required to ensure that these discoveries can become translational, clinically usable therapies. Clinical progress requires the development of new, more accurate models of the human disease state, multifaceted investigations that address multiple critical components in wound repair, and more innovative research strategies that harness both the existing knowledge and the potential of new advances across disciplines.

Surgical Treatment of Diabetic Foot Ulcers Complicated by Osteomyelitis with Gentamicin-Loaded Calcium Sulphate-Hydroxyapatite Biocomposite

Diabetic foot ulcers, complicated by osteomyelitis, can be treated by surgical resection, dead space filling with gentamicin-loaded calcium sulphate-hydroxyapatite (CaS-HA) biocomposite, and closure of soft tissues and skin. To assess the feasibility of this treatment regimen, we conducted a multicenter retrospective cohort study of patients after failed conventional treatments. From 13 hospitals we included 64 patients with forefoot (n = 41 (64%)), midfoot (n = 14 (22%)), or hindfoot (n = 9 (14%)) ulcers complicated by osteomyelitis. Median follow-up was 43 (interquartile range, 20–61) weeks. We observed wound healing in 54 patients (84%) and treatment success (wound healing without ulcer recurrence) in 42 patients (66%). Treatment failures (no wound healing or ulcer recurrence) led to minor amputations in four patients (6%) and major amputations in seven patients (11%). Factors associated with treatment failures in univariable Cox regression analysis were gentamicin-resistant osteomyelitis (hazard ratio (HR), 3.847; 95%-confidence interval (CI), 1.065–13.899), hindfoot ulcers (HR, 3.624; 95%-CI, 1.187–11.060) and surgical procedures with gentamicin-loaded CaS-HA biocomposite that involved minor amputations (HR, 3.965; 95%-CI, 1.608–9.777). In this study of patients with diabetic foot ulcers, complicated by osteomyelitis, surgical treatment with gentamicin-loaded CaS-HA biocomposite was feasible and successful in 66% of patients. A prospective trial of this treatment regimen, based on a uniform treatment protocol, is required.

Application and Clinical Effectiveness of Antibiotic-Loaded Bone Cement to Promote Soft Tissue Granulation in the Treatment of Neuropathic Diabetic Foot Ulcers Complicated by Osteomyelitis: A Randomized Controlled Trial

This study explored the clinical effectiveness of antibiotic-loaded bone cement on primary treatment of diabetic foot infection. This is a randomized controlled study, including thirty-six patients with diabetic foot ulcer complicated by osteomyelitis who had undergone treatment between May 2018 and December 2019. Patients were randomly divided into control group (group A) and study group (group B). Patients in the intervention group received antibiotic-loaded bone cement repair as primary treatment, while patients in the control group received conventional vacuum sealing draining treatment. Clinical endpoints were assessed and compared between the two groups, including wound healing time, wound bacterial conversion, NRS pain score, number of wound dressing changes, and average hospitalization time. All patients were followed up for a period of 12 months after discharge. Results show that compared with the control group, patients in the study group had significant difference in the number of patients for baseline pathogens eradication, short NRS pain score, hospital length of stay and cost, wound surface reduction, healing time, low rate of complications, and infection recurrence. Based on the findings, we conclude that antibiotic-loaded bone cement can be used for treatment of wound in patient with diabetic foot infection. It can help to control wound infections, shorten hospital length of stay, reduce medical cost, and relieve both doctors' and patients' burden. The application of antibiotic-loaded bone cement is suitable for diabetic wound with soft tissue infection or osteomyelitis.

Topical Antibiotic Elution in a Collagen-Rich Hydrogel Successfully Inhibits Bacterial Growth and Biofilm Formation In Vitro

Chronic wounds are a prominent concern, accounting for $25 billion of health care costs annually. Biofilms have been implicated in delayed wound closure, but they are susceptible to developing antibiotic resistance and treatment options continue to be limited. A novel collagen-rich hydrogel derived from human extracellular matrix presents an avenue for treating chronic wounds by providing appropriate extracellular proteins for healing and promoting neovascularization. Using the hydrogel as a delivery system for localized secretion of a therapeutic dosage of antibiotics presents an attractive means of maximizing delivery while minimizing systemic side effects. We hypothesize that the hydrogel can provide controlled elution of antibiotics leading to inhibition of bacterial growth and disruption of biofilm formation. The rate of antibiotic elution from the collagen-rich hydrogel and the efficacy of biofilm disruption was assessed with Pseudomonas aeruginosa Bacterial growth inhibition, biofilm disruption, and mammalian cell cytotoxicity were quantified using in vitro models. The antibiotic-loaded hydrogel showed sustained release of antibiotics for up to 24 h at therapeutic levels. The treatment inhibited bacterial growth and disrupted biofilm formation at multiple time points. The hydrogel was capable of accommodating various classes of antibiotics and did not result in cytotoxicity in mammalian fibroblasts or adipose stem cells. The antibiotic-loaded collagen-rich hydrogel is capable of controlled antibiotic release effective for bacteria cell death without native cell death. A human-derived hydrogel that is capable of eluting therapeutic levels of antibiotic is an exciting prospect in the field of chronic wound healing.

Therapeutic application of adipose-derived stromal vascular fraction in diabetic foot

Diabetic foot is one of the severest complications of diabetes. In severe cases, this disease may be lead to amputation or even death due to secondary infection and ischemic necrosis. Since the ineffectiveness of traditional therapy, autologous stem cell transplantation has been used to treat diabetic foot. This simple, safe, and effective therapy is expected to be applied and promoted in the future.In this review, we described the detailed pathogenesis of diabetic foot and the common clinical treatments currently used. We also revealed vascular remodeling as the potential mechanism of therapeutic functions of adipose-derived stromal vascular fraction (SVF) in treating diabetic foot.

Antimicrobial activity of mesenchymal stem cells against Staphylococcus aureus

Introduction

There have been limited advances in the treatment of bone and joint infections, which currently involves a combination of surgery and antibiotic administration. There is a timely need in orthopedics to develop more effective and less invasive forms of antimicrobial prophylaxis and treatment. The antibacterial effect of adult tissue-derived mesenchymal stem cells (MSCs) has recently been investigated against Escherichia coli and Staphylococcus aureus. The main mechanism of action is postulated to be via MSC production of the cationic antimicrobial peptide, LL-37.

Methods

This study examines the antimicrobial activity of adipose-derived human MSCs (ASCs) on S. aureus, specifically examining the role of LL-37 and regulation of its expression. Bacteria colony-forming unit (CFU) assay was used to assess antimicrobial activity.

Results

Our results showed that the ASC-conditioned medium significantly inhibited the growth of S. aureus under standard culture conditions with or without the continued presence of ASCs. Also, the treatment of ASCs with 1,25-dihydroxy vitamin D₃ elevated LL-37 expression and enhanced their antimicrobial activity. In support, treatment with the vitamin D receptor inhibitor, GW0742, blocked the antimicrobial activity of ASCs.

Conclusion

Our findings clearly demonstrate the antimicrobial activity of adult ASCs against S. aureus and implicate a key regulatory role for vitamin D. Further testing in in vivo models is being pursued to assess the potential application of ASCs as a biocompatible, adjunct treatment for musculoskeletal infections.

D-PLEX100 in an Abdominal Surgery Incision Model in Miniature Swine: Safety Study

Surgical site infections (SSIs) are a common surgical-related complication. To avoid these complications, a new biodegradable polymer-lipid encapsulation matrix that provides controlled release of doxycycline (doxycycline/polymer-lipid encapsulation matrix [D-PLEX]) has been developed. The aim of this comprehensive study was to evaluate the potential safety of D-PLEX₁₀₀ in abdominal surgical site. D-PLEX₁₀₀ was administered into incisions of abdominal surgical site in Yucatan miniature swine, which were followed for up to 6 months and compared to sham-control swine. The D-PLEX₁₀₀ mass did not migrate from the incisional site, and there was no evidence for systemic toxicity or other safety concerns. Surgical incision sites, including the peritoneal surface, were fully healed at 6 months in all animals. Most of the D-PLEX₁₀₀ mass was absorbed during the first 3 months, and by 6 months, D-PLEX₁₀₀ was fully absorbed. Toxicokinetic evaluation revealed that doxycycline concentrations were evident at 30 minutes and persisted to 8 days (71 mg/kg) or at least 15 days (284 mg/kg) and were no longer present in plasma by day 29. This study supports the safety of D-PLEX₁₀₀ and its favorable degradability profile. A clinical study is being performed to assess the safety and the efficacy of D-PLEX₁₀₀ to prevent human abdominal SSIs.

Successful treatment of a diabetic foot ulcer with exposed bone using Trigona honey: a case study

Many studies have shown that honey might improve wound healing. However, its efficacy for large wounds which may be followed by a systemic effect remains unclear. The effectiveness of honey-based dressings in treating large diabetic foot ulcers (DFU) is still unknown. This study presents the case of a 38-year-old female patient presenting with an extensive infected DFU with exposed bone. The DFU was treated with propolis-enriched Trigona honey, used as a single treatment, in a home visit setting. After two months' follow-up, the wound exhibited complete re-epithelialisation despite the patient's initial poor condition.

Optimal management of diabetic foot osteomyelitis: challenges and solutions

Purpose: Diabetic foot osteomyelitis (DFO) is the most frequent infection associated with diabetic foot ulcers, occurs in >20% of moderate infections and 50%-60% of severe infections, and is associated with high rates of amputation. DFO represents a challenge in both diagnosis and therapy, and many consequences of its condition are related to late diagnosis, delayed referral, or ill-indicated treatment. This review aimed to analyze the current evidence on DFO management and to discuss advantages and disadvantages of different treatment options. Methods: A narrative review of the evidence was begun by searching Medline and PubMed databases for studies using the keywords "management", "diabetic foot", "osteomyelitis", and "diabetic foot osteomyelitis" from 2008 to 2018. Results: We found a great variety of studies focusing on both medical and surgical therapies showing a similar rate of effectiveness and outcomes; however, the main factors in choosing one over the other seem to be associated with the presence of soft-tissue infection or ischemia and the clinical presentation of DFO. Conclusion: Further randomized controlled trials with large samples and long-term follow-up are necessary to demonstrate secondary outcomes, such as recurrence, recurrent ulceration, and reinfection associated with both medical and surgical options.

Effect of Induced Membrane Formation Followed by Polymethylmethacrylate Implantation on Diabetic Foot Ulcer Healing When Revascularization Is Not Feasible

No study has investigated the role of induced membrane (IM) formation in treating diabetic foot ulcer (DFU). This retrospective study was aimed (1) at evaluating the potential role of a two-staged surgical approach, comprising polymethylmethacrylate (PMMA) implantation and IM formation, in the treatment of DFU and (2) at comparing the results of those with routine wound debridement in patients with DFUs and nonrevascularized peripheral arterial disease (PAD). Fifty patients with infected DFUs who were not candidates for vascular interventions were enrolled between February 2016 and April 2018 and assigned to the PMMA group (n = 28) and conventional group (n = 22). The healing rate, major amputation rate, duration of healing, frequency of debridement procedures, patient survival rate, and reulceration of DFUs were determined. The Mann-Whitney U test, independent sample t-test, and χ ² or Fisher exact test were used in statistical analysis. Overall clinical outcomes were statistically different between the groups (Z = -2.495, P = 0.013). In the PMMA group, 16 patients (57.1%) with intact IM formation achieved ulceration healing at 13.1 ± 3.7 weeks with a mean number of debridements of 1.3 ± 0.4, which were significantly different compared to those values in 5 patients of the conventional group (22.7%, P = 0.014; healing duration: 26.4 ± 7.8 weeks, P = 0.016; mean number of debridements: 3.6 ± 0.5, P ≤ 0.001). At a mean 16.8 ± 4.3-month follow-up, patient survival rates were 92.9% and 68.2% in the PMMA and conventional groups, respectively (P = 0.032). The major amputation rate and reulceration of DFUs were similar between the groups. The two-staged surgical approach is an available, effective modality for improving healing of DFUs. This study provides preliminary information of IM formation followed by PMMA implantation in the management of DFUs in PAD when revascularization is not feasible.