The treatment of diabetic foot infections: focus on ertapenem

Teicoplanin-Decorated Reduced Graphene Oxide Incorporated Silk Protein Hybrid Hydrogel for Accelerating Infectious Diabetic Wound Healing and Preventing Diabetic Foot Osteomyelitis

Developing hybrid hydrogel dressings with anti-inflammatory, antioxidant, angiogenetic, and antibiofilm activities with higher bone tissue penetrability to accelerate diabetic wound healing and prevent diabetic foot osteomyelitis (DFO) is highly desirable in managing diabetic wounds. Herein, the glycopeptide teicoplanin is used for the first time as a green reductant to chemically reduce graphene oxide (GO). The resulting teicoplanin-decorated reduced graphene oxide (rGO) is incorporated into a mixture of silk proteins (SP) and crosslinked with genipin to yield a physicochemically crosslinked rGO-SP hybrid hydrogel. This hybrid hydrogel exhibits high porosity, self-healing, shear-induced thinning, increased cell proliferation and migration, and mechanical properties suitable for tissue engineering. Moreover, the hybrid hydrogel eradicates bacterial biofilms with a high penetrability index in agar and hydroxyapatite disks covered with biofilms, mimicking bone tissue. In vivo, the hybrid hydrogel accelerates the healing of noninfected wounds in a diabetic rat and infected wounds in a diabetic mouse by upregulating anti-inflammatory cytokines and downregulating matrix metalloproteinase-9, promoting M2 macrophage polarization and angiogenesis. The implantation of hybrid hydrogel into the infected site of mouse tibia improves bone regeneration. Hence, the rGO-SP hybrid hydrogel can be a promising wound dressing for treating infectious diabetic wounds, providing a further advantage in preventing DFO.

Treatment Strategies Against Diabetic Foot Ulcer: Success so Far and the Road Ahead

BACKGROUND

Diabetic foot ulcer (DFU) is one of the leading complications of type-2 diabetes mellitus. It is associated with neuropathy and peripheral arterial disease of the lower limb in patients with diabetes. There are four stages of wound healing, namely hemostasis phase, inflammatory phase, proliferative phase and maturation phase. In the case of DFU, all these stages are disturbed which lead to delay in healing and consequently to lower limb amputation. Conventional dosage forms like tablets, creams, ointments, gels and capsules have been used for the treatment of diabetic foot ulcer for many years.

INTRODUCTION

In this review, the global prevalence as well as etiopathogenesis related to diabetic foot ulcer have been discussed. The potential role of various synthetic and herbal drugs, as well as their conventional dosage forms in the effective management of DFU have been discussed in detail.

METHODS

Structured search of bibliographic databases from previously published peer-reviewed research papers was explored and data has been represented in terms of various approaches that are used for the treatment of DFU.

RESULTS

About 148 papers, including both research and review articles, were included in this review to produce a comprehensive as well as a readily understandable article. A series of herbal and synthetic drugs have been discussed along with their current status of treatment in terms of dose and mechanism of action.

CONCLUSION

DFU has become one of the most common complications in patients having diabetes for more than ten years. Hence, understanding the root cause and its successful treatment is a big challenge because it depends upon multiple factors such as the judicious selection of drugs as well as proper control of blood sugar level. Most of the drugs that have been used so far either belong to the category of antibiotics, antihyperglycaemic or they have been repositioned. In clinical practice, much focus has been given to dressings that have been used to cover the ulcer. The complete treatment of DFU is still a farfetched dream to be achieved and it is expected that combination therapy of herbal and synthetic drugs with multiple treatment pathways could be able to offer better management of DFU.

Common Pathogens and Antibiotic Sensitivity Profiles of Infected Diabetic Foot Ulcers in Saudi Arabia

We sought to define the type and antibiotic sensitivity response of pathogens isolated from diabetic foot ulcers based on ulcer location and Wagner classification. This retrospective analysis was done among 126 patients between 40 and 70 years of age at the Prince Sultan Military Medical City, Riyadh, Saudi Arabia, using the swab culture method for microbiological assessment. Data on demographic variables, ulcer sites (location), and depth of ulcer (Wagner classification) were also collected. A total of 134 pathogens were isolated from 126 patients. The most common gram-negative pathogen identified was Pseudomonas aeruginosa (15.6%), followed by Klebsiella spp (6.7%). The most common gram-positive pathogen was Staphylococcus aureus (35%), followed by Streptococcus (8.9%). The most widely accepted antibiotic to which the gram-negative bacteria were sensitive was gentamycin (20.1%), followed by ciprofloxacin (19%). The most routinely used antibiotic in the treatment of the gram-positive bacteria was erythromycin (16%), with trimethoprim-sulfamethoxazole (14.1%) being the next most effective. In conclusion, Pseudomonas aeruginosa, Klebsiella spp, Staphylococcus aureus, and Streptococcus were the most common causes of diabetic foot infections. However, the frequency of encountered pathogens and respective sensitivity to antibiotic therapy may be influenced by the location site and severity of the ulceration.

Efficacy and safety of IV/PO moxifloxacin and IV piperacillin/tazobactam followed by PO amoxicillin/clavulanic acid in the treatment of diabetic foot infections: results of the RELIEF study

OBJECTIVE

The aim was to compare the efficacy and safety of two antibiotic regimens in patients with diabetic foot infections (DFIs).

METHODS

Data of a subset of patients enrolled in the RELIEF trial with DFIs requiring surgery and antibiotics were evaluated retrospectively. DFI was diagnosed on the basis of the modified Wagner, University of Texas, and PEDIS classification systems. Patients were randomized to receive either intravenous/oral moxifloxacin (MXF, N = 110) 400 mg q.d. or intravenous piperacillin/tazobactam 4.0/0.5 g t.d.s. followed by oral amoxicillin/clavulanate 875/125 mg b.d. (PIP/TAZ-AMC, N = 96), for 7-21 days until the end of treatment (EOT). The primary endpoint was clinical cure rates in the per-protocol (PP) population at the test-of-cure visit (TOC, 14-28 days after EOT).

RESULTS

There were no significant differences between the demographic characteristics of PP patients in either treatment group. At TOC, MXF and PIP/TAZ-AMC had similar efficacy in both the PP and intent-to-treat (ITT) populations: MXF: 76.4 % versus PIP/TAZ-AMC: 78.1 %; 95 % confidence interval (CI) -14.5 %, 9.0 % in the PP population; MXF: 69.9 % versus PIP/TAZ-AMC: 69.1 %; 95 % CI -12.4 %, 12.1 % in the ITT population. The overall bacteriological success rates were similar in both treatment groups (MXF: 71.7 % versus PIP/TAZ-AMC: 71.8 %; 95 % CI -16.9 %, 10.7 %). A similar proportion of patients (ITT population) experienced any adverse events in both treatment groups (MXF: 30.9 % versus PIP/TAZ-AMC: 31.8 %, respectively). Death occurred in three MXF-treated patients and one PIP/TAZ-AMC-treated patient; these were unrelated to the study drugs.

CONCLUSION

Moxifloxacin has shown favorable safety and efficacy profiles in DFI patients and could be an alternative antibiotic therapy in the management of DFI.

CLINICAL TRIAL

NCT00402727.

Ertapenem for treatment of osteomyelitis: a case series

BACKGROUND

Ertapenem is a once-daily broad spectrum carbapenem that is increasingly used to treat polymicrobial osteomyelitis due to diabetic foot and traumatic wound infections. However, limited data exists on ertapenem use for osteomyelitis. This study aimed to characterize outcomes and adverse effects with empiric use of ertapenem for osteomyelitis.

FINDINGS

A total of 112 patients presenting to Duke, Durham Regional or Durham VA Medical Centers with a suspected diagnosis of osteomyelitis and ertapenem use from 11/2001 to 8/2009 were screened, and 12 subjects met inclusion criteria for the study. Mean age was 60 ± 16 years, 68% were female, 75% were Caucasian, and the most common comorbidities included diabetes (58%), peripheral vascular disease (42%), and history of tobacco use (75%). Over half of the patients presented to a primary care clinic or emergency room greater than six months after the onset of clinical symptoms. Bone culture was obtained for diagnostic guidance in only two cases; and surgical intervention was pursued in three cases. Patients received a mean duration of 34.6 ± 7.8 days of therapy, and in three cases, subsequent suppressive oral antibiotics were given. Six (50%) patients met criteria for clinical success, defined as resolution of clinical signs and symptoms of infection such that discontinuation of antibiotics was deemed appropriate at end of ertapenem therapy, without recurrence at one year follow-up. No adverse drug effects were noted.

CONCLUSIONS

In this case series of mostly community-acquired, lower extremity osteomyelitis, bone biopsy was infrequent, and an average six-week course of empiric ertapenem was well-tolerated with curative rates of 50% at one year.

Methicillin-resistant Staphylococcus aureus in diabetic foot infections

Diabetic foot ulcers are often complicated by infection. Among pathogens, Staphylococcus aureus predominates. The prevalence of methicillin-resistant S. aureus (MRSA) in infected foot ulcers is 15-30% and there is an alarming trend for increase in many countries. There are also data that recognize new strains of MRSA that are resistant to vancomycin. The risk for MRSA isolation increases in the presence of osteomyelitis, nasal carriage of MRSA, prior use of antibacterials or hospitalization, larger ulcer size and longer duration of the ulcer. The need for amputation and surgical debridement increases in patients infected with MRSA. Infections of mild or moderate severity caused by community-acquired MRSA can be treated with cotrimoxazole (trimethoprim/sulfamethoxazole), doxycycline or clindamycin when susceptibility results are available, while severe community-acquired or hospital-acquired MRSA infections should be managed with glycopeptides, linezolide or daptomycin. Dalbavancin, tigecycline and ceftobiprole are newer promising antimicrobial agents active against MRSA that may also have a role in the treatment of foot infections if more data on their efficacy and safety become available.