[Highly resistant pathogens in patients with diabetic foot syndrome with special reference to methicillin-resistant Staphylococcus aureus infections]

Microbial profile of diabetic foot infections in Trinidad and Tobago

AIMS

To examine the microbiologic profile of diabetic foot infections in order to guide empiric antibiotic choices.

METHODS

All patients with moderate-severe diabetic foot infections at a tertiary care facility were identified from July 2011 to June 2012. Culture samples were routinely collected before empiric antibiotics were commenced. Retrospective chart review was performed to extract the following data: demographics, clinical details, empiric antibiotic choice and microbiologic data. Descriptive analyses were performed using SPSS 12.0.

RESULTS

There were 139 patients at a mean age of 56.9 ± 12.4 years. Mixed poly-microbial infections were present in 56.8% of cases. Of 221 organisms isolated, 64.7% were gram-negative aerobes, 32.1% were gram-positive aerobes and 3.2% were obligate anaerobes. Multidrug resistant organisms were encountered in 25.9% of cases and included ESBL producers (11.3%), MRSA (4.5%) and VRE (1.4%). Both ciprofloxacin and ceftazidime had good overall anti-microbial activity against gram-negative (68% and 62%, respectively) and gram-positive pathogens (69% and 48%, respectively). Obligate anaerobes were uncommonly isolated due to institutional constraints.

CONCLUSION

In this environment, both ciprofloxacin and ceftazidime provide good broad-spectrum anti-microbial activity against the commonly isolated pathogens. Either agent can be used as single agent empiric therapy in patients with moderate/severe diabetic infections in our setting. Although institutional limitations precluded isolation of anaerobes in most cases, there is sufficient evidence for anti-anaerobic agents to be recommended as a part of empiric therapy.

Diagnosis and management of infection in the diabetic foot

Foot infections are common in persons with diabetes mellitus. Most diabetic foot infections occur in a foot ulcer, which serves as a point of entry for pathogens. Unchecked, infection can spread contiguously to involve underlying tissues, including bone. A diabetic foot infection is often the pivotal event leading to lower extremity amputation, which account for about 60% of all amputations in developed countries. Given the crucial role infections play in the cascade toward amputation, all clinicians who see diabetic patients should have at least a basic understanding of how to diagnose and treat this problem.

Molecular epidemiology of Staphylococcus aureus strains isolated from inpatients with infected diabetic foot ulcers in an Algerian University Hospital

Staphylococcus aureus is the most common pathogen cultured from diabetic foot infection (DFI). The consequence of its spread to soft tissue and bony structures is a major causal factor for lower-limb amputation. The objective of the study was to explore ecological data and epidemiological characteristics of S. aureus strains isolated from DFI in an Algerian hospital setting. Patients were included if they were admitted for DFI in the Department of Diabetology at the Annaba University Hospital from April 2011 to March 2012. Ulcers were classified according to the Infectious Diseases Society of America/International Working Group on the Diabetic Foot classification system. All S. aureus isolates were analysed. Using oligonucleotide arrays, S. aureus resistance and virulence genes were determined and each isolate was affiliated to a clonal complex. Among the 128 patients, 277 strains were isolated from 183 samples (1.51 isolate per sample). Aerobic Gram-negative bacilli were the most common isolated organisms (54.9% of all isolates). The study of ecological data highlighted the extremely high rate of multidrug-resistant organisms (MDROs) (58.5% of all isolates). The situation was especially striking for S. aureus [(85.9% were methicillin-resistant S. aureus (MRSA)], Klebsiella pneumonia (83.8%) and Escherichia coli (60%). Among the S. aureus isolates, 82.2% of MRSA belonged to ST239, one of the most worldwide disseminated clones. Ten strains (13.7%) belonged to the European clone PVL+ ST80. ermA, aacA-aphD, aphA, tetM, fosB, sek, seq, lukDE, fnbB, cap8 and agr group 1 genes were significantly associated with MRSA strains (p <0.01). The study shows for the first time the alarming prevalence of MDROs in DFI in Algeria.

A prospective, multi-center study: factors related to the management of diabetic foot infections

The Turkish Association of Clinical Microbiology and Infectious Diseases, Diabetic Foot Infections Working Group conducted a prospective study to determine the factors affecting the outcomes of diabetic foot infections. A total of 96 patients were enrolled in the study. Microbiological assessment was performed in 86 patients. A total of 115 causative bacteria were isolated from 71 patients. The most frequently isolated bacterial species was Pseudomonas aeruginosa (n = 21, 18.3%). Among cases with bacterial growth, 37 patients (43%) were infected with 38 (33%) antibiotic-resistant bacteria. The mean (±SD) antibiotics cost was 2,220.42 (±994.59) USD in cases infected with resistant bacteria, while it was 1,206.60 (±1,160.6) USD in patients infected with susceptible bacteria (p < 0.001). According to the logistic regression analysis, the risk factors related to the growth of resistant bacteria were previous amputation (p = 0.018, OR = 7.229) and antibiotics administration within the last 30 days (p = 0.032, OR = 3.796); that related to the development of osteomyelitis was wound size >4.5 cm(2) (p = 0.041, OR = 2.8); and that related to the failure of the treatment was the growth of resistant bacteria (p = 0.016, OR = 5.333). Diabetic foot osteomyelitis is usually a chronic infection and requires surgical therapy. Amputation is the accepted form of treatment for osteomyelitis. Limited limb-saving surgery and prolonged antibiotic therapy directed toward the definitive causative bacteria are most appropriate. This may decrease limb loss through amputations. As a result the infections caused by resistant bacteria may lead to a high cost of antibiotherapy, prolonged hospitalization duration, and failure of the treatment.

Expert opinion on the management of infections in the diabetic foot

This update of the International Working Group on the Diabetic Foot incorporates some information from a related review of diabetic foot osteomyelitis (DFO) and a systematic review of the management of infection of the diabetic foot. The pathophysiology of these infections is now well understood, and there is a validated system for classifying the severity of infections based on their clinical findings. Diagnosing osteomyelitis remains difficult, but several recent publications have clarified the role of clinical, laboratory and imaging tests. Magnetic resonance imaging has emerged as the most accurate means of diagnosing bone infection, but bone biopsy for culture and histopathology remains the criterion standard. Determining the organisms responsible for a diabetic foot infection via culture of appropriately collected tissue specimens enables clinicians to make optimal antibiotic choices based on culture and sensitivity results. In addition to culture-directed antibiotic therapy, most infections require some surgical intervention, ranging from minor debridement to major resection, amputation or revascularization. Clinicians must also provide proper wound care to ensure healing of the wound. Various adjunctive therapies may benefit some patients, but the data supporting them are weak. If properly treated, most diabetic foot infections can be cured. Providers practising in developing countries, and their patients, face especially challenging situations.

Ceftobiprole: First reported experience in osteomyelitis

A 74-year-old man with long-standing diabetes presented with advanced infection of the right forefoot associated with septic arthritis and osteomyelitis involving the second and third metatarsophalangeal joints. Polymicrobial infection, which included methicillin-resistant Staphylococcus aureus, was documented. First-line antibiotic therapy, which included vancomycin, was not tolerated. A durable cure was obtained following a six-week course of intravenous ceftobiprole medocaril combined with local surgery. The present report is the first to administer intravenous ceftobiprole medocaril to a patient with methicillin-resistant S aureus-associated septic arthritis and osteomyelitis.

New insights in diabetic foot infection

Foot ulcers are common in diabetic patients, have a cumulative lifetime incidence rate as high as 25% and frequently become infected. The spread of infection to soft tissue and bone is a major causal factor for lower-limb amputation. For this reason, early diagnosis and appropriate treatment are essential, including treatment which is both local (of the foot) and systemic (metabolic), and this requires coordination by a multidisciplinary team. Optimal treatment also often involves extensive surgical debridement and management of the wound base, effective antibiotic therapy, consideration for revascularization and correction of metabolic abnormalities such as hyperglycemia. This article focuses on diagnosis and management of diabetic foot infections in the light of recently published data in order to help clinicians in identification, assessment and antibiotic therapy of diabetic foot infections.

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.

Vacuum-assisted closure instill as a method of sterilizing massive venous stasis wounds prior to split thickness skin graft placement

Patients with massive venous stasis ulcers that have very high bacterial burdens represent some of the most difficult wounds to manage. The vacuum-assisted closure (VAC) device is known to optimise wound bed preparation; however, these patients have too high a bacterial burden for simple VAC application to facilitate this function. We present the application of the VAC with instillation of dilute Dakins solution as a way of bacterial eradication in these patients. Five patients with venous stasis ulcers greater than 200 cm(2) that were colonised with greater than 10(5) bacteria were treated with the VAC instill for 10 days with 12.5% Dakins solution, instilled for 10 minutes every hour. Two patients had multi-drug-resistant pseudomonas, three with MRSA. All the five had negative quantitative cultures, prior to split thickness skin graft with 100% take and complete healing at 1 year. Adequate delivery of bactericidal agents to the infected tissue can be very difficult, especially while promoting tissue growth. By providing a single delivery system for a bactericidal agent for a short period of time followed by a growth stimulating therapy, the VAC instill provides a unique combination that appears to maximise wound bed preparation.

Management of diabetic foot infections in an era of increasing microbial resistance

Diabetic foot infections cause substantial morbidity, incur significant costs, and may lead to amputation. Resistant organisms, particularly methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant gram-negative organisms, are becoming more prevalent. Optimal management of diabetic foot infections is multimodal, and includes not only antimicrobial therapy but also biomechanical support and offloading, local wound care, glycemic control, assessment and treatment of underlying vascular disease, and surgical therapy when warranted. Antimicrobial therapy should be targeted at the likely etiologic agents and should take into consideration the depth and severity of infection. With expansion of the reservoir of resistant organisms, obtaining reliable deep cultures can help focus antimicrobial therapy against the dominant pathogens. Newer agents against resistant gram-positive and gram-negative organisms show promise in the treatment of diabetic foot infections.

Skin and soft tissue infections in hospitalised patients with diabetes: culture isolates and risk factors associated with mortality, length of stay and cost

AIMS/HYPOTHESIS

Skin and soft tissue infections (SSTIs) cause substantial morbidity in persons with diabetes. There are few data on pathogens or risk factors associated with important outcomes in diabetic patients hospitalised with SSTIs.

METHODS

Using a clinical research database from CareFusion, we identified 3,030 hospitalised diabetic patients with positive culture isolates and a diagnosis of SSTI in 97 US hospitals between 2003 and 2007. We classified the culture isolates and analysed their association with the anatomic location of infection, mortality, length of stay and hospital costs.

RESULTS

The only culture isolate with a significantly increased prevalence was methicillin-resistant Staphylococcus aureus (MRSA); prevalence for infection of the foot was increased from 11.6 to 21.9% (p < 0.0001) and for non-foot locations from 14.0% to 24.6% (p = 0.006). Patients with non-foot (vs foot) infections were more severely ill at presentation and had higher mortality rates (2.2% vs 1.0%, p < 0.05). Significant independent risk factors associated with higher mortality rates included having a polymicrobial culture with Pseudomonas aeruginosa (OR 3.1), a monomicrobial culture with other gram-negatives (OR 8.9), greater illness severity (OR 1.9) and being transferred from another hospital (OR 5.1). These factors and need for major surgery were also independently associated with longer length of stay and higher costs.

CONCLUSIONS/INTERPRETATION

Among diabetic patients hospitalised with SSTI from 2003 to 2007, only MRSA increased in prevalence. Patients with non-foot (vs foot) infections were more severely ill. Independent risk factors for increased mortality rates, length of stay and costs included more severe illness, transfer from another hospital and wound cultures with Pseudomonas or other gram-negatives.

[Principles of treatment for deep infections of the diabetic foot]

Infections are the typical complications of ulcers related to the neuropathic diabetic foot. The loss of the foot or sepsis is the consequence due to the progression of an untreated infection. Therefore, prophylaxis of ulcer formation is the key to lower the rate of amputation. If infection has occurred antibiotics and non-weight bearing are indicated. Abscesses and phlegmons can be localized by the clinical findings, ultrasound, x-rays, computer tomography and MRI and immediate surgical treatment is necessary to prevent further spreading. In the chronic phase dead tissue, necrotic tendons and bones need to be resected. Closure of the skin can be achieved by secondary healing or other methods of plastic surgery. Persistent bony prominences have to be removed and instabilities need fusion operations. In this way many amputations can be avoided or the extent of amputation can be noticeably reduced.

Diabetic foot infections: a team-oriented review of medical and surgical management

As the domestic and international incidence of diabetes and metabolic syndrome continues to rise, health care providers need to continue improving management of the long-term complications of the disease. Emergency department visits and hospital admissions for diabetic foot infections are increasingly commonplace, and a like-minded multidisciplinary team approach is needed to optimize patient care. Early recognition of severe infections, medical stabilization, appropriate antibiotic selection, early surgical intervention, and strategic plans for delayed reconstruction are crucial components of managing diabetic foot infections. The authors review initial medical and surgical management and staged surgical reconstruction of diabetic foot infections in the inpatient setting.

A stepwise approach to the surgical management of severe diabetic foot infections

Foot infections are common among diabetic patients with ulceration and are a major cause of hospitalization and lower extremity amputation. Aggressive and emergent surgical intervention is essential in the face of life- or limb-threatening infection to achieve limb salvage and survival. Critical limb ischemia, neuropathy, and an impaired host complicate the treatment of a severe diabetic foot infection. A severe diabetic foot infection carries a 25% risk of major amputation. For this reason, surgery should be coordinated with a well-functioning multidisciplinary team that specializes in diabetic limb preservation. Timing of surgery and strategies employed should be understood and agreed on by both the surgical and medical disciplines managing the diabetic patient with a limb-threatening infection. The overall strategy for surgically managing a severe diabetic foot infection is as follows: the first step is infection control through aggressive and extensive surgical debridement, the second step is a comprehensive vascular assessment with possible vascular surgery and/or endovascular intervention, and the final step is soft tissue and skeletal reconstruction after infection is eradicated to obtain wound closure and limb salvage. A consistent stepwise surgical approach combined with sound surgical principles is paramount for successful management of the severe diabetic foot infection. The authors discuss their stepwise surgical approach to reduce the mortality, morbidity, psychological distress, and length of hospitalization associated with life- or limb-threatening diabetic foot infections.

Risk factors for developing osteomyelitis in patients with diabetic foot wounds

AIMS

Osteomyelitis worsens the prognosis in the diabetic foot, but predisposing factors remain largely undefined. In a prospectively followed cohort we assessed risk factors for developing osteomyelitis.

METHODS

We enrolled consecutive persons with diabetes who presented to a managed-care diabetes disease management program. The patients underwent standardized assessments. We monitored for all foot complications, defined infections by criteria consistent with International Working Group guidelines, and defined osteomyelitis as a positive culture from a bone specimen.

RESULTS

1666 persons were enrolled, 50% male, mean age 69 years. Over a mean of 27.2 months of follow-up, 151 patients developed foot infections, 30 (19.9%) of which involved bone. Independent risk factors for osteomyelitis were: wounds that extended to bone or joint (relative risk [RR]=23.1), previous history of a wound prior to enrollment (RR=2.2), and recurrent or multiple wounds during the study period (RR=1.9).

CONCLUSIONS

In this study population, managed in a specialized diabetic foot care center, the results suggest that independent risk factors for developing osteomyelitis are deep, recurrent and multiple wounds. These results may help clinicians target their efforts at diagnosing foot osteomyelitis to the highest risk patients.

Risk factors and healing impact of multidrug-resistant bacteria in diabetic foot ulcers

AIM

To determine the risk factors for acquiring multidrug-resistant organisms (MDRO) and their impact on outcome in infected diabetic foot ulcers.

METHODS

Patients hospitalized in our diabetic foot unit for an episode of infected foot ulcer were prospectively included. Diagnosis of infection was based on clinical findings using the International Working Group on the Diabetic Foot-Infectious Diseases Society of America (IWGDF-ISDA) system, and wound specimens were obtained for bacterial cultures. Each patient was followed-up for 1 year. Univariate analysis was performed to compare infected ulcers according to the presence or absence of MDRO; logistic regression was used to identify explanatory variables for MDRO presence. Factors related to healing time were evaluated by univariate and multivariate survival analyses.

RESULTS

MDRO were isolated in 45 (23.9%) of the 188 patients studied. Deep and recurrent ulcer, previous hospitalization, HbA(1c) level, nephropathy and retinopathy were significantly associated with MDRO-infected ulceration. By multivariate analysis, previous hospitalization (OR=99.6, 95% CI=[19.9-499.0]) and proliferative retinopathy (OR=7.4, 95% CI=[1.6-33.7]) significantly increased the risk of MDRO infection. Superficial ulcers were associated with a significant decrease in healing time, whereas neuroischaemic ulcer, proliferative retinopathy and high HbA(1c) level were associated with an increased healing time. In the multivariate analysis, presence of MDRO had no significant influence on healing time.

CONCLUSION

MDRO are pathogens frequently isolated from diabetic foot infection in our foot clinic. Nevertheless, their presence appears to have no significant impact on healing time if early aggressive treatment, as in the present study, is given, including empirical broad-spectrum antibiotic treatment, later adjusted according to microbiological findings.

New developments in diagnosing and treating diabetic foot infections

Foot infections are common in persons with diabetes and are often the proximate cause of lower extremity amputation. There have been many publications in the past few years dealing with the appropriate ways to diagnose and treat diabetic foot infections. This review presents information gathered from a comprehensive, ongoing surveillance of the literature (published and abstracts) over the past 4 years. Prospective studies have now defined the epidemiology of diabetic foot infections, as well as methods to score and classify the wounds. Several recently published guidelines can assist clinicians in managing these infections. The etiologic agents of infection have been well-defined, and the prevalence of multi-drug-resistance pathogens is growing. Molecular methods offer great promise for quicker and more sensitive diagnosis of infection. New antimicrobial agents, both systemic and topical, as well as novel local treatments, have been shown to be effective in various studies. Improved methods of deploying older agents have added to the variety of treatment approaches now available. Several adjunctive treatments may benefit some patients but their role is as yet unclear. While there is much yet to learn about the most cost-effective ways to diagnose and treat diabetic foot infections the main effort is now to disseminate the available information and facilitate employing the evidence-based guideline recommendations.

A stepwise approach to the surgical management of severe diabetic foot infections

Foot infections are common among diabetic patients with ulceration and are a major cause of hospitalization and lower extremity amputation. Aggressive and emergent surgical intervention is essential in the face of life- or limb-threatening infection to achieve limb salvage and survival. Critical limb ischemia, neuropathy, and an impaired host complicate the treatment of a severe diabetic foot infection. A severe diabetic foot infection carries a 25% risk of major amputation. For this reason, surgery should be coordinated with a well-functioning multidisciplinary team that specializes in diabetic limb preservation. Timing of surgery and strategies employed should be understood and agreed on by both the surgical and medical disciplines managing the diabetic patient with a limb-threatening infection. The overall strategy for surgically managing a severe diabetic foot infection is as follows: the first step is infection control through aggressive and extensive surgical debridement, the second step is a comprehensive vascular assessment with possible vascular surgery and/or endovascular intervention, and the final step is soft tissue and skeletal reconstruction after infection is eradicated to obtain wound closure and limb salvage. A consistent stepwise surgical approach combined with sound surgical principles is paramount for successful management of the severe diabetic foot infection. The authors discuss their stepwise surgical approach to reduce the mortality, morbidity, psychological distress, and length of hospitalization associated with life- or limb-threatening diabetic foot infections.

Diabetic foot ulcers — a comprehensive review

As the incidence of diabetes mellitus is increasing globally, complications related to this endocrine disorder are also mounting. Because of the large number of patients, foot ulcers developing in the feet of diabetics have become a public health problem. The predisposing factors include abnormal plantar pressure points, foot deformities, and minor trauma. Vulnerable feet usually already have vascular insufficiency and peripheral neuropathy. The complex nature of these ulcers deserves special care. The most useful prognostic feature for healing remains the ulcer depth, ulcers heal poorly if they clearly involve underlying tendons, ligament or joints and, particularly, when gangrenous tissue is seen. Local treatment of the ulcer consists of repeated debridement and dressing. No 'miraculous' outcome is expected, even with innovative agents like skin cover synthetics, growth factors and stem cells. Simple surgery like split skin grafting or minor toe amputations may be necessary. Sophisticated surgery like flap coverages are indicated for younger patients. The merits of an intact lower limb with an abnormal foot have to be weighed against amputation and prosthesis in the overall planning of limb salvage or sacrifice. If limb salvage is the decision, additional means like oxygen therapy, and other alternative medicines, might have benefits. The off-loading of footwear should always be a major consideration as a prevention of ulcer formation.

Empirical therapy for diabetic foot infections: are there clinical clues to guide antibiotic selection?

Initial antibiotic therapy for diabetic foot infections is usually empirical. Several principles may help to avoid selecting either an unnecessarily broad or inappropriately narrow regimen. First, clinically severe infections require broad-spectrum therapy, while less severe infections may not. Second, aerobic Gram-positive cocci, particularly Staphylococcus aureus (including methicillin-resistant S. aureus (MRSA) for patients at high-risk) should always be covered. Third, therapy should also be targeted at aerobic Gram-negative pathogens if the infection is chronic or has failed to respond to previous antibiotic therapy. Fourth, anti-anaerobe agents should be considered for necrotic or gangrenous infections on an ischaemic limb. Parenteral therapy is needed for severe infections, but oral therapy is adequate for most mild or moderate infections.

Optimal management of uncomplicated skin and skin structure infections of the lower extremity

Uncomplicated skin and skin structure infections of the lower extremity are almost always curable when properly diagnosed and promptly treated with antibiotics, but they can cause serious complications if not treated appropriately. These infections are caused often by Staphylococcus aureus and less commonly by Streptococcus pyogenes. Initial treatment is usually empiric. Although the most suitable oral treatment is likely cephalosporin, other options include beta-lactamase inhibitor-penicillin combinations and penicillinase-resistant penicillins. In some cases, incision and drainage or debridement may be required.

Diagnosis and treatment of diabetic foot infections

EXECUTIVE SUMMARY: 1. Foot infections in patients with diabetes cause substantial morbidity and frequent visits to health care professionals and may lead to amputation of a lower extremity. 2. Diabetic foot infections require attention to local (foot) and systemic (metabolic) issues and coordinated management, preferably by a multidisciplinary foot-care team (A-II). The team managing these infections should include, or have ready access to, an infectious diseases specialist or a medical microbiologist (B-II). 3. The major predisposing factor to these infections is foot ulceration, which is usually related to peripheral neuropathy. Peripheral vascular disease and various immunological disturbances play a secondary role. 4. Aerobic Gram-positive cocci (especially Staphylococcus aureus) are the predominant pathogens in diabetic foot infections. Patients who have chronic wounds or who have recently received antibiotic therapy may also be infected with Gram-negative rods, and those with foot ischemia or gangrene may have obligate anaerobic pathogens. 5. Wound infections must be diagnosed clinically on the basis of local (and occasionally systemic) signs and symptoms of inflammation. Laboratory (including microbiological) investigations are of limited use for diagnosing infection, except in cases of osteomyelitis (B-II). 6. Send appropriately obtained specimens for culture before starting empirical antibiotic therapy in all cases of infection, except perhaps those that are mild and previously untreated (B-III). Tissue specimens obtained by biopsy, ulcer curettage, or aspiration are preferable to wound swab specimens (A-I). 7. Imaging studies may help diagnose or better define deep, soft-tissue purulent collections and are usually needed to detect pathological findings in bone. Plain radiography may be adequate in many cases, but MRI (in preference to isotope scanning) is more sensitive and specific, especially for detection of soft-tissue lesions (A-I). 8. Infections should be categorized by their severity on the basis of readily assessable clinical and laboratory features (B-II). Most important among these are the specific tissues involved, the adequacy of arterial perfusion, and the presence of systemic toxicity or metabolic instability. Categorization helps determine the degree of risk to the patient and the limb and, thus, the urgency and venue of management. 9. Available evidence does not support treating clinically uninfected ulcers with antibiotic therapy (D-III). Antibiotic therapy is necessary for virtually all infected wounds, but it is often insufficient without appropriate wound care. 10. Select an empirical antibiotic regimen on the basis of the severity of the infection and the likely etiologic agent(s) (B-II). Therapy aimed solely at aerobic Gram-positive cocci may be sufficient for mild-to-moderate infections in patients who have not recently received antibiotic therapy (A-II). Broad-spectrum empirical therapy is not routinely required but is indicated for severe infections, pending culture results and antibiotic susceptibility data (B-III). Take into consideration any recent antibiotic therapy and local antibiotic susceptibility data, especially the prevalence of methicillin-resistant S. aureus (MRSA) or other resistant organisms. Definitive therapy should be based on both the culture results and susceptibility data and the clinical response to the empirical regimen (C-III). 11. There is only limited evidence with which to make informed choices among the various topical, oral, and parenteral antibiotic agents. Virtually all severe and some moderate infections require parenteral therapy, at least initially (C-III). Highly bioavailable oral antibiotics can be used in most mild and in many moderate infections, including some cases of osteomyelitis (A-II). Topical therapy may be used for some mild superficial infections (B-I). 12. Continue antibiotic therapy until there is evidence that the infection has resolved but not necessarily until a wound has healed. Suggestions for the duration of antibiotic therapy are as follows: for mild infections, 12 weeks usually suffices, but some require an additional 12 weeks; for moderate and severe infections, usually 24 weeks is sufficient, depending on the structures involved, the adequacy of debridement, the type of soft-tissue wound cover, and wound vascularity (A-II); and for osteomyelitis, generally at least 46 weeks is required, but a shorter duration is sufficient if the entire infected bone is removed, and probably a longer duration is needed if infected bone remains (B-II). 13. If an infection in a clinically stable patient fails to respond to 1 antibiotic courses, consider discontinuing all antimicrobials and, after a few days, obtaining optimal culture specimens (C-III). 14. Seek surgical consultation and, when needed, intervention for infections accompanied by a deep abscess, extensive bone or joint involvement, crepitus, substantial necrosis or gangrene, or necrotizing fasciitis (A-II). Evaluating the limb's arterial supply and revascularizing when indicated are particularly important. Surgeons with experience and interest in the field should be recruited by the foot-care team, if possible. 15. Providing optimal wound care, in addition to appropriate antibiotic treatment of the infection, is crucial for healing (A-I). This includes proper wound cleansing, debridement of any callus and necrotic tissue, and, especially, off-loading of pressure. There is insufficient evidence to recommend use of a specific wound dressing or any type of wound healing agents or products for infected foot wounds. 16. Patients with infected wounds require early and careful follow-up observation to ensure that the selected medical and surgical treatment regimens have been appropriate and effective (B-III). 17. Studies have not adequately defined the role of most adjunctive therapies for diabetic foot infections, but systematic reviews suggest that granulocyte colony-stimulating factors and systemic hyperbaric oxygen therapy may help prevent amputations (B-I). These treatments may be useful for severe infections or for those that have not adequately responded to therapy, despite correcting for all amenable local and systemic adverse factors. 18. Spread of infection to bone (osteitis or osteomyelitis) may be difficult to distinguish from noninfectious osteoarthropathy. Clinical examination and imaging tests may suffice, but bone biopsy is valuable for establishing the diagnosis of osteomyelitis, for defining the pathogenic organism(s), and for determining the antibiotic susceptibilities of such organisms (B-II). 19. Although this field has matured, further research is much needed. The committee especially recommends that adequately powered prospective studies be undertaken to elucidate and validate systems for classifying infection, diagnosing osteomyelitis, defining optimal antibiotic regimens in various situations, and clarifying the role of surgery in treating osteomyelitis (A-III).

Diabetic foot infections: stepwise medical and surgical management

Foot complications are common among diabetic patients; foot ulcers are among the more serious consequences. These ulcers frequently become infected, with potentially disastrous progression to deeper spaces and tissues. If not treated promptly and appropriately, diabetic foot infections can become incurable or even lead to septic gangrene, which may require foot amputation. Diagnosing infection in a diabetic foot ulcer is based on clinical signs and symptoms of inflammation. Properly culturing an infected lesion can disclose the pathogens and provide their antibiotic susceptibilities. Specimens for culture should be obtained after wound debridement to avoid contamination and optimise identification of pathogens. Staphylococcus aureus is the most common isolate in these infections; the increasing incidence of methicillin-resistant S. aureus over the past two decades has further complicated antibiotic treatment. While chronic infections are often polymicrobial, many acute infections in patients not previously treated with antibiotics are caused by a single pathogen, usually a gram-positive coccus. We offer a stepwise approach to treating diabetic foot infections. Most patients must first be medically stabilised and any metabolic aberrations should be addressed. Antibiotic therapy is not required for uninfected wounds but should be carefully selected for all infected lesions. Initial therapy is usually empirical but may be modified according to the culture and sensitivity results and the patient's clinical response. Surgical intervention is usually required in cases of retained purulence or advancing infection despite optimal medical therapy. Possible additional indications for surgical procedures include incision and drainage of an abscess, debridement of necrotic material, removal of any foreign bodies, arterial revascularisation and, when needed, amputation. Most foot ulcers occur on the plantar surface of the foot, thus requiring a plantar incision for any drainage procedure.

Ertapenem versus piperacillin/tazobactam for diabetic foot infections (SIDESTEP): prospective, randomised, controlled, double-blinded, multicentre trial

BACKGROUND

Diabetic foot infections are a common and serious problem, yet few randomised trials of adequate quality have compared the efficacy of the various antibiotic regimens available for their treatment. Our aim was to assess the efficacy and safety of ertapenem versus piperacillin/tazobactam for foot infections.

METHODS

We did a randomised, double-blinded, multicentre trial in adults (n=586) with diabetes and a foot infection classified as moderate-to-severe and requiring intravenous antibiotics. We assigned patients intravenous ertapenem (1 g daily; n=295) or piperacillin/tazobactam (3.375 g every 6 h; n=291) given for a minimum of 5 days, after which oral amoxicillin/clavulanic acid (875/125 mg every 12 h) could be given for up to 23 days. Investigators retained the option to administer vancomycin to patients in either group to ensure adequate coverage for potentially antibiotic resistant Enterococcus spp and meticillin-resistant Staphylococcus aureus (MRSA). Our primary outcome was the proportion of patients with a favourable clinical response (cure or improvement) on the day that intravenous antibiotic was discontinued. Analyses were by an evaluable-patient only approach. This study is registered with , number NCT00229112.

FINDINGS

Of the 576 patients treated, 445 were available for assessment at the end of intravenous therapy. Both baseline characteristics and favourable clinical response rates were similar for the 226 who received ertapenem and the 219 who received piperacillin/tazobactam (94%vs 92%, respectively; between treatment difference 1.9%, 95% CI -2.9 to 6.9). Rates of favourable microbiological responses (eradication rates and clinical outcomes, by pathogen) and adverse events did not differ between groups.

INTERPRETATION

Clinical and microbiological outcomes for patients treated with ertapenem were equivalent to those for patients treated with piperacillin/tazobactam, suggesting that this once-daily antibiotic should be considered for parenteral therapy of diabetic foot infections, when deemed appropriate.

Daptomycin for treating infected diabetic foot ulcers: evidence from a randomized, controlled trial comparing daptomycin with vancomycin or semi-synthetic penicillins for complicated skin and skin-structure infections

OBJECTIVES

The predominant pathogens causing diabetic foot infections are Gram-positive cocci, many of which are now resistant to commonly prescribed antibiotics. Daptomycin is a new agent that is active against most Gram-positive pathogens. To compare the effectiveness of daptomycin against semi-synthetic penicillins or vancomycin, we analysed the subset of diabetic patients with an infected ulcer enrolled in two randomized, controlled investigator-blind trials of patients with complicated skin and soft-tissue infections presumptively caused by Gram-positive organisms.

PATIENTS AND METHODS

Patients with a diabetic ulcer infection were prospectively stratified to ensure they were equally represented in the treatment groups, then randomized to either daptomycin [4 mg/kg every 24 h intravenously (iv)] or a pre-selected comparator (vancomycin or a semi-synthetic penicillin) for 7-14 days.

RESULTS

Among 133 patients with a diabetic ulcer infection, 103 were clinically evaluable; 47 received daptomycin and 56 received a comparator. Most infections were monomicrobial, and Staphylococcus aureus was the predominant pathogen. Success rates for patients treated with daptomycin or the comparators were not statistically different for clinical (66% versus 70%, respectively; 95% CI, -14.4, 21.8) or microbiological (overall or by pathogen) outcomes. Both treatments were generally well tolerated, with most adverse events of mild to moderate severity.

CONCLUSIONS

The clinical and microbiological efficacy and safety of daptomycin were similar to those of commonly used comparator antibiotics for treating infected diabetic foot ulcers caused by Gram-positive pathogens. Daptomycin should be considered for treating these infections, especially those caused by resistant Gram-positive pathogens.

New and experimental approaches to treatment of diabetic foot ulcers: a comprehensive review of emerging treatment strategies

Diabetic foot ulcers occur in up to 15% of all diabetic patients and are a leading cause of nontraumatic amputation worldwide. Neuropathy, abnormal foot biomechanics, peripheral vascular disease and external trauma are the major contributors to the development of a foot ulcer in the diabetic patient. Therapy today includes repeated debridement, offloading, and dressings, for lower grade ulcers, and broad spectrum antibiotics and occasionally limited or complete amputation for higher grades, requiring a team effort of health care workers from various specialties. The large population affected by diabetic foot ulcers and the high rates of failure ending with amputation even with the best therapeutic regimens, have resulted in the development of new therapies and are the focus of this review. These include new off loading techniques, dressings from various materials, methods to promote wound closure using artificial skin grafts, different growth factors or wound bed modulators and methods of debridement. These new techniques are promising but still mostly unproven and traditional approaches cannot be replaced. New and generally more expensive therapies should be seen as adding to traditional approaches.

Advances in the treatment of diabetic foot infections

Lower extremity infections are frequent causes of substantial morbidity and mortality in the diabetic population, and these infections consume a large portion of resources expended on diabetic complications. Gram-positive cocci, particularly Staphylococcus aureus, are the most important pathogens in diabetic foot infections. These organisms are predominant both in mild infections (which are often monomicrobial), as well as in more severe and chronic infected wounds that more often have a polymicrobial cause. Appropriate clinical assessment and culturing of infections are critical in establishing the presence and severity of infection, in detecting osteomyelitis, and in directing the optimal treatment approach. Following necessary debridement and other surgical interventions (e.g., bone resection, revascularization), appropriate antibiotic therapy is a cornerstone of managing the infected lower extremity. Peripheral vascular (i.e., arterial) insufficiency and the increasing prevalence of antibiotic resistance are primary barriers to successfully managing these infections. Fortunately, alternative delivery systems (e.g., antibiotic beads, impregnated sponges) and novel antibiotics (e.g., levofloxacin, linezolid) are providing possible solutions to the challenges posed by this physically, emotionally, and financially devastating condition.

Treating Foot Infections in Diabetic Patients: A Randomized, Multicenter, Open‐Label Trial of Linezolid versus Ampicillin‐Sulbactam/Amoxicillin‐Clavulanate

Foot infections in diabetic patients are predominantly caused by gram-positive cocci, many of which are now antibiotic resistant. Because linezolid is active against these pathogens, we compared the efficacy and safety of intravenous and oral formulations with that of intravenous ampicillin-sulbactam and intravenous and oral amoxicillin-clavulanate given for 7-28 days in a randomized, open-label, multicenter study of all types of foot infection in diabetic patients (ratio of linezolid to comparator drug recipients, 2:1). Among 371 patients, the clinical cure rates associated with linezolid and the comparators were statistically equivalent overall (81% vs. 71%, respectively) but were significantly higher for linezolid-treated patients with infected foot ulcers (81% vs. 68%; P=.018) and for patients without osteomyelitis (87% vs. 72%; P=.003). Cure rates were comparable for inpatients and outpatients and for both oral and intravenous formulations. Drug-related adverse events were significantly more common in the linezolid group, but they were generally mild and reversible. Linezolid was at least as effective as aminopenicillin/beta-lactamase inhibitors for treating foot infections in diabetic patients.

Diabetic foot ulcers

Ulceration of the foot in diabetes is common and disabling and frequently leads to amputation of the leg. Mortality is high and healed ulcers often recur. The pathogenesis of foot ulceration is complex, clinical presentation variable, and management requires early expert assessment. Interventions should be directed at infection, peripheral ischaemia, and abnormal pressure loading caused by peripheral neuropathy and limited joint mobility. Despite treatment, ulcers readily become chronic wounds. Diabetic foot ulcers have been neglected in health-care research and planning, and clinical practice is based more on opinion than scientific fact. Furthermore, the pathological processes are poorly understood and poorly taught and communication between the many specialties involved is disjointed and insensitive to the needs of patients.

Methicillin-resistant Staphylococcus aureus in the diabetic foot clinic: a worsening problem

AIMS

To determine if there has been a change in the prevalence of pathogenic organisms in foot ulcers in diabetic patients in 2001 compared with our previous study in 1998.

METHODS

A retrospective analysis of wound swabs taken from infected foot ulcers in diabetic patients attending the outpatient clinic in the Manchester Foot Hospital over a twelve-month period. A total of 63 patients with positive wound swabs were identified.

RESULTS

Gram-positive aerobic bacteria still predominate (84.2%) and the commonest single isolate remains Staphylococcus aureus (79.0%) which is higher than we previously reported. MRSA was isolated in 30.2% of the patients which is almost double the proportion of MRSA-affected patients three years ago. This did not appear to be related to prior antibiotic usage. There was no increase in hospitalisation because of MRSA infection.

CONCLUSIONS

The problem of MRSA continues to increase despite the precautions taken to prevent MRSA spread. There is a need for a multi-centre study looking into the prevalence of MRSA in diabetic foot ulcer and how this can be reduced in the diabetic foot clinic.