Foot infections are a common and serious problem in persons with diabetes. Diabetic foot infections (DFIs) typically begin in a wound, most often a neuropathic ulceration. While all wounds are colonized with microorganisms, the presence of infection is defined by ≥2 classic findings of inflammation or purulence. Infections are then classified into mild (superficial and limited in size and depth), moderate (deeper or more extensive), or severe (accompanied by systemic signs or metabolic perturbations). This classification system, along with a vascular assessment, helps determine which patients should be hospitalized, which may require special imaging procedures or surgical interventions, and which will require amputation. Most DFIs are polymicrobial, with aerobic gram-positive cocci (GPC), and especially staphylococci, the most common causative organisms. Aerobic gram-negative bacilli are frequently copathogens in infections that are chronic or follow antibiotic treatment, and obligate anaerobes may be copathogens in ischemic or necrotic wounds. Wounds without evidence of soft tissue or bone infection do not require antibiotic therapy. For infected wounds, obtain a post-debridement specimen (preferably of tissue) for aerobic and anaerobic culture. Empiric antibiotic therapy can be narrowly targeted at GPC in many acutely infected patients, but those at risk for infection with antibiotic-resistant organisms or with chronic, previously treated, or severe infections usually require broader spectrum regimens. Imaging is helpful in most DFIs; plain radiographs may be sufficient, but magnetic resonance imaging is far more sensitive and specific. Osteomyelitis occurs in many diabetic patients with a foot wound and can be difficult to diagnose (optimally defined by bone culture and histology) and treat (often requiring surgical debridement or resection, and/or prolonged antibiotic therapy). Most DFIs require some surgical intervention, ranging from minor (debridement) to major (resection, amputation). Wounds must also be properly dressed and off-loaded of pressure, and patients need regular follow-up. An ischemic foot may require revascularization, and some nonresponding patients may benefit from selected adjunctive measures. Employing multidisciplinary foot teams improves outcomes. Clinicians and healthcare organizations should attempt to monitor, and thereby improve, their outcomes and processes in caring for DFIs.

These guidelines were developed and issued on behalf of the Infectious Diseases Society of America. a B.A.L. served as the chairman and A.R.B. served as the vice chairman of the Infectious Diseases Society of America Guidelines Committee on Diabetic Foot Infections.b Deceased.

The International Working Group on the Diabetic Foot (IWGDF) has published evidence‐based guidelines on the prevention and management of diabetic foot disease since 1999. This guideline is on the diagnosis and treatment of foot infection in persons with diabetes and updates the 2015 IWGDF infection guideline. On the basis of patient, intervention, comparison, outcomes (PICOs) developed by the infection committee, in conjunction with internal and external reviewers and consultants, and on systematic reviews the committee conducted on the diagnosis of infection (new) and treatment of infection (updated from 2015), we offer 27 recommendations. These cover various aspects of diagnosing soft tissue and bone infection, including the classification scheme for diagnosing infection and its severity. Of note, we have updated this scheme for the first time since we developed it 15 years ago. We also review the microbiology of diabetic foot infections, including how to collect samples and to process them to identify causative pathogens. Finally, we discuss the approach to treating diabetic foot infections, including selecting appropriate empiric and definitive antimicrobial therapy for soft tissue and for bone infections, when and how to approach surgical treatment, and which adjunctive treatments we think are or are not useful for the infectious aspects of diabetic foot problems. For this version of the guideline, we also updated four tables and one figure from the 2016 guideline. We think that following the principles of diagnosing and treating diabetic foot infections outlined in this guideline can help clinicians to provide better care for these patients.

Recommendations Classification/diagnosis Diabetic foot infection must be diagnosed clinically, based on the presence of local or systemic signs or symptoms of inflammation (strong; low). Assess the severity of any diabetic foot infection using the Infectious Diseases Society of America/International Working Group on the Diabetic Foot classification scheme (strong; moderate). Osteomyelitis For an infected open wound, perform a probe‐to‐bone test; in a patient at low risk for osteomyelitis, a negative test largely rules out the diagnosis, while in a high‐risk patient, a positive test is largely diagnostic (strong; high). Markedly elevated serum inflammatory markers, especially erythrocyte sedimentation rate, are suggestive of osteomyelitis in suspected cases (weak; moderate). A definite diagnosis of bone infection usually requires positive results on microbiological (and, optimally, histological) examinations of an aseptically obtained bone sample, but this is usually required only when the diagnosis is in doubt or determining the causative pathogen's antibiotic susceptibility is crucial (strong; moderate). A probable diagnosis of bone infection is reasonable if there are positive results on a combination of diagnostic tests, such as probe‐to‐bone, serum inflammatory markers, plain X‐ray, magnetic resonance imaging (MRI) or radionuclide scanning (strong; weak). Avoid using results of soft tissue or sinus tract specimens for selecting antibiotic therapy for osteomyelitis as they do not accurately reflect bone culture results (strong; moderate). Obtain plain X‐rays of the foot in all cases of non‐superficial diabetic foot infection (strong; low). Use MRI when an advanced imaging test is needed for diagnosing diabetic foot osteomyelitis (strong; moderate). When MRI is not available or contraindicated, consider a white blood cell‐labelled radionuclide scan, or possibly single‐photon emission computed tomography (CT) and CT (SPECT/CT) or fluorine‐18‐fluorodeoxyglucose positron emission tomography/CT scans (weak; moderate). Assessing severity At initial evaluation of any infected foot, obtain vital signs and appropriate blood tests, debride the wound and probe and assess the depth and extent of the infection to establish its severity (strong; moderate). At initial evaluation, assess arterial perfusion and decide whether and when further vascular assessment or revascularization is needed (strong; low). Microbiological considerations Obtain cultures, preferably of a tissue specimen rather than a swab, of infected wounds to determine the causative microorganisms and their antibiotic sensitivity (strong; high). Do not obtain repeat cultures unless the patient is not clinically responding to treatment, or occasionally for infection control surveillance of resistant pathogens (strong; low). Send collected specimens to the microbiology laboratory promptly, in sterile transport containers, accompanied by clinical information on the type of specimen and location of the wound (strong; low). Surgical treatment Consult...

Diabetic foot disease results in a major global burden for patients and the health care system. The International Working Group on the Diabetic Foot (IWGDF) has been producing evidence‐based guidelines on the prevention and management of diabetic foot disease since 1999. In 2019, all IWGDF Guidelines have been updated based on systematic reviews of the literature and formulation of recommendations by multidisciplinary experts from all over the world. In this document, the IWGDF Practical Guidelines, we describe the basic principles of prevention, classification, and treatment of diabetic foot disease, based on the six IWGDF Guideline chapters. We also describe the organizational levels to successfully prevent and treat diabetic foot disease according to these principles and provide addenda to assist with foot screening. The information in these practical guidelines is aimed at the global community of health care professionals who are involved in the care of persons with diabetes. Many studies around the world support our belief that implementing these prevention and management principles is associated with a decrease in the frequency of diabetes‐related lower extremity amputations. We hope that these updated practical guidelines continue to serve as reference document to aid health care providers in reducing the global burden of diabetic foot disease.

OBJECTIVE -To prospectively determine risk factors for foot infection in a cohort of people with diabetes.RESEARCH DESIGN AND METHODS -We evaluated then followed 1,666 consecutive diabetic patients enrolled in a managed care-based outpatient clinic in a 2-year longitudinal outcomes study. At enrollment, patients underwent a standardized general medical examination and detailed foot assessment and were educated about proper foot care. They were then rescreened at scheduled intervals and also seen promptly if they developed any foot problem.RESULTS -During the evaluation period, 151 (9.1%) patients developed 199 foot infections, all but one involving a wound or penetrating injury. Most patients had infections involving only the soft tissue, but 19.9% had bone culture-proven osteomyelitis. For those who developed a foot infection, compared with those who did not, the risk of hospitalization was 55.7 times greater (95% CI 30.3-102.2; P Ͻ 0.001) and the risk of amputation was 154.5 times greater (58.5-468.5; P Ͻ 0.001). Foot wounds preceded all but one infection. Significant (P Ͻ 0.05) independent risk factors for foot infection from a multivariate analysis included wounds that penetrated to bone (odds ratio 6.7), wounds with a duration Ͼ30 days (4.7), recurrent wounds (2.4), wounds with a traumatic etiology (2.4), and presence of peripheral vascular disease (1.9).CONCLUSIONS -Foot infections occur relatively frequently in individuals with diabetes, almost always follow trauma, and dramatically increase the risk of hospitalization and amputation. Efforts to prevent infections should be targeted at people with traumatic foot wounds, especially those that are chronic, deep, recurrent, or associated with peripheral vascular disease.

While foot infections in persons with diabetes are initially treated empirically, therapy directed at known causative organisms may improve the outcome. Many studies have reported on the bacteriology of diabetic foot infections (DFIs) over the past 25 years, but the results have varied and have often been contradictory. A number of studies have found that Staphylococcus aureus is the main causative pathogen (12,34,35), but two recent investigations reported a predominance of gram-negative aerobes (20, 47). The role of anaerobes is particularly unclear, because in many studies specimens were not collected or cultured properly to recover these organisms. Among those that did use appropriate methods, some report that anaerobes play a minimal role (2,7,15,21,46), while others suggest that Bacteroides fragilis is the predominant anaerobe isolated (1,3,17,57).These discrepancies could be partly due to differences in the causative organisms occurring over time, geographical variations, or the types and severity of infection included in the studies (1,20,47,51). In addition, some studies used a relatively small number of specimens, failed to report recent or concomitant antibiotic therapy, did not ensure that the specimen collection techniques would exclude superficial or colonizing organisms, or even make clear whether or not the wound was clinically infected. Also, laboratory processing of the samples may have been inadequate to grow anaerobes or fastidious organisms, and protocols that classify potential pathogens (e.g., coagulase-negative staphylococci [CoNS] or Corynebacterium species) as colonizers may have been used (4,46,49).While S. aureus and beta-hemolytic streptococci are widely recognized as pathogens in early DFIs, the role of other frequently isolated organisms is less clear to both the clinician and the microbiology laboratory. Previous studies have shown that when optimal specimen collection, transport, and culture techniques are used, multiple organisms are usually recovered from DFIs (6,14,23,29,30,45,55). Furthermore, some studies suggest that the interactions of organisms within these polymicrobial mixtures lead to the production of virulence factors, such as hemolysins, proteases, and collagenases, as well as short-chain fatty acids, that cause inflammation, impede wound healing, and contribute to the chronicity of the infection (5,52,53,56). In such mixtures, biofilms that impede the penetration of antimicrobial agents into the infected site may also form (25). Thus, the presence of multiple species can have important clinical implications that should not be overlooked (5, 23).

Background The management of complex orthopedic infections usually includes a prolonged course of intravenous antibiotic agents. We investigated whether oral antibiotic therapy is noninferior to intravenous antibiotic therapy for this indication. Methods We enrolled adults who were being treated for bone or joint infection at 26 U.K. centers. Within 7 days after surgery (or, if the infection was being managed without surgery, within 7 days after the start of antibiotic treatment), participants were randomly assigned to receive either intravenous or oral antibiotics to complete the first 6 weeks of therapy. Follow-on oral antibiotics were permitted in both groups. The primary end point was definitive treatment failure within 1 year after randomization. In the analysis of the risk of the primary end point, the noninferiority margin was 7.5 percentage points. Results Among the 1054 participants (527 in each group), end-point data were available for 1015 (96.3%). Treatment failure occurred in 74 of 506 participants (14.6%) in the intravenous group and 67 of 509 participants (13.2%) in the oral group. Missing end-point data (39 participants, 3.7%) were imputed. The intention-to-treat analysis showed a difference in the risk of definitive treatment failure (oral group vs. intravenous group) of −1.4 percentage points (90% confidence interval [CI], −4.9 to 2.2; 95% CI, −5.6 to 2.9), indicating noninferiority. Complete-case, per-protocol, and sensitivity analyses supported this result. The between-group difference in the incidence of serious adverse events was not significant (146 of 527 participants [27.7%] in the intravenous group and 138 of 527 [26.2%] in the oral group; P = 0.58). Catheter complications, analyzed as a secondary end point, were more common in the intravenous group (9.4% vs. 1.0%). Conclusions Oral antibiotic therapy was noninferior to intravenous antibiotic therapy when used during the first 6 weeks for complex orthopedic infection, as assessed by treatment failure at 1 year. (Funded by the National Institute for Health Research; OVIVA Current Controlled Trials number, ISRCTN91566927.)