Background/Objectives: Current international guidelines recommend choosing an empirical antibiotic regimen for treating diabetic foot infections (DFI) based largely on clinical severity of the infection and local microbiological epidemiology. This may lead to selecting unnecessarily broad-spectrum initial empiric antibiotic therapy. Methods: Using data from our hospital in a large Swiss city, we retrospectively analyzed the performance of the Gram-stained smears of predominantly deep surgical DFI specimens processed by our microbiology laboratory in predicting the microorganism grown on standard cultures. We excluded episodes with paucibacillary stain results, which we interpret as contamination. Results: Among 1235 operated moderates or severe DFIs, Gram-stained smear was reported in 321 (26%) of cases, and showed bacteria in 172 episodes (54%) of these. Overall, among Gram stain results with organism seen, the sensitivity, specificity, accuracy, positive and negative predictive values of the Gram stain smear when compared with the cultures was 56%, 93%, 97%, and 38%, respectively. The accuracy was 73%. The corresponding statistical values specifically for Gram-negative bacteria were 61%, 97%, 50%, and 82%. Conclusions: The results of routine Gram stain smears of deep intraoperative DFI specimens generally lack sufficient sensitivity, and was only useful to reasonably exclude a DFI caused predominantly by Gram-negative bacteria. For Gram-stained smears results to be useful for guiding antibiotic stewardship, we need prospective trials to assess their value in different types of DFIs.

Diabetic foot ulcers in developing countries often become infected. The healthcare systems are often not equipped to conduct the culture and the sensitivity tests required for prescribing a targeted antibiotic treatment for diabetic foot infection (DFI).

We evaluate antibiotic stewardship programmes for DFIs, at every level of health care, with an emphasis on resource-poor settings such as in Africa.

The management of DFI very often is adapted to the financial and practical realities of the resource-poor regions. The application of the point-of-care Gram stain of deep tissue samples is efficient, rapid, low cost and ubiquitously available. Upon the identification of the predominant pathogen in the Gram stain, a semi-quantitative preemptive antibiotic treatment can be started in accordance with the World Health Organization Aware, Watch and Restrict Essential Medicine List. This list is catered to every country and is a powerful tool. However, some basic knowledge of the local microbiological epidemiology is necessary to choose the most appropriate agent. We report our experience on using the rapidly available Gram stain for narrowing the preemptive choice of listed antibiotic agents, as an economic tool for antibiotic stewardship in DFIs.

In the practical and resource-saving management of DFI, the 'therapeutic' use of Gram stains is not common in resource-rich countries but should be added to the arsenal of the general efforts for antibiotic stewardship.

Securing an early accurate diagnosis of diabetic foot infections and assessment of their severity are of paramount importance since these infections can cause great morbidity and potential mortality and present formidable challenges in surgical and antimicrobial treatment.

In June 2022, we searched the literature using PubMed and EMBASE for published studies on the diagnosis of diabetic foot infection (DFI). On the basis of pre-determined criteria, we reviewed prospective controlled, as well as non-controlled, studies in English. We then developed evidence statements based on the included papers.

We selected a total of 64 papers that met our inclusion criteria. The certainty of the majority of the evidence statements was low because of the weak methodology of nearly all of the studies. The available data suggest that diagnosing diabetic foot infections on the basis of clinical signs and symptoms and classified according to the International Working Group of the Diabetic Foot/Infectious Diseases Society of America scheme correlates with the patient's likelihood of the need for hospitalisation, lower extremity amputation, and risk of death. Elevated levels of selected serum inflammatory markers such as erythrocyte sedimentation rate (ESR), C-reactive protein and procalcitonin are supportive, but not diagnostic, of soft tissue infection. Culturing tissue samples of soft tissues or bone, when care is taken to avoid contamination, provides more accurate microbiological information than culturing superficial (swab) samples. Although non-culture techniques, especially next-generation sequencing, are likely to identify more bacteria from tissue samples including bone than standard cultures, no studies have established a significant impact on the management of patients with DFIs. In patients with suspected diabetic foot osteomyelitis, the combination of a positive probe-to-bone test and elevated ESR supports this diagnosis. Plain X-ray remains the first-line imaging examination when there is suspicion of diabetic foot osteomyelitis (DFO), but advanced imaging methods including magnetic resonance imaging (MRI) and nuclear imaging when MRI is not feasible help in cases when either the diagnosis or the localisation of infection is uncertain. Intra-operative or non-per-wound percutaneous biopsy is the best method to accurately identify bone pathogens in case of a suspicion of a DFO. Bedside percutaneous biopsies are effective and safe and are an option to obtain bone culture data when conventional (i.e. surgical or radiological) procedures are not feasible.

The results of this systematic review of the diagnosis of diabetic foot infections provide some guidance for clinicians, but there is still a need for more prospective controlled studies of high quality.

To retrospectively evaluate clinical and microbiological outcomes after combined surgical and medical therapy for diabetic foot infections (DFIs), stratifying between the empirical versus the targeted nature, and between an empirical broad versus a narrow-spectrum, antibiotic therapy.

We retrospectively assessed the rate of ultimate therapeutic failures for each of three types of initial postoperative antibiotic therapy: adequate empirical therapy; culture-guided therapy; and empirical inadequate therapy with a switch to targeted treatment based on available microbiological results.

We included data from 332 patients who underwent 716 DFI episodes of surgical debridement, including partial amputations. Clinical failure occurred in 40 of 194 (20.6%) episodes where adequate empirical therapy was given, in 77 of 291 (26.5%) episodes using culture-guided (and correct) therapy from the start, and in 73 of 231 (31.6%) episodes with switching from empirical inadequate therapy to culture-targeted therapy. Equally, a broad-spectrum antibiotic choice could not alter this failure risk. Group comparisons, Kaplan-Meier curves and Cox regression analyses failed to show either statistical superiority or inferiority of any of the initial antibiotic strategies.

In this study, the microbiological adequacy of the initial antibiotic regimen after (surgical) debridement for DFI did not alter therapeutic outcomes. We recommend that clinicians follow the stewardship approach of avoiding antibiotic de-escalation and start with a narrow-spectrum regimen based on the local epidemiology.

To demonstrate that a syndromic stewardship intervention can safely reduce antipseudomonal antibiotic use in the treatment of inpatient diabetic foot infections (DFIs).

From November 2017 through March 2018, we performed an antimicrobial stewardship intervention that included creation of a DFI best-practice guideline, implementation of an electronic medical record order set, and targeted education of key providers. We conducted a retrospective before-and-after study evaluating guideline adherent antipseudomonal antibiotic use 1 year before and after the intervention using interrupted time-series analysis.

University of Nebraska Medical Center, a 718-bed academic medical center in Omaha, Nebraska.

The study included 193 adults aged ≥19 years (105 in the preintervention group and 88 in the postintervention group) admitted to non-intensive care units whose primary reason for antibiotic treatment was diabetic foot infection (DFI).

Guideline-adherent use of antipseudomonal antibiotics increased from 39% before the intervention to 68% after the intervention (P ≤ .0001). Antipseudomonal antibiotic use decreased from 538 days of therapy (DOT) per 1,000 DFI patient days (PD) before the intervention to 272 DOT per 1,000 DFI PD after the intervention (P < .0001), with a statistically significant decrease in both level of use and slope of change. We did not detect any changes in length of stay, readmission, amputation rate, subsequent positive Clostridioides difficile testing, or mortality.

Our 3-component intervention of guideline creation, implementation of an order set, and targeted education was associated with a significant decrease in antipseudomonal antibiotic use in the management of inpatient DFIs. DFIs are common and should be considered as opportunities for syndromic stewardship intervention.

We investigated the impact of the total length of systemic antibiotic therapy (ABT) and its initial intravenous (IV) part on clinical failure (CF) and microbiological failure (MF) in diabetic foot infections (DFIs).

In this single-center, retrospective, unmatched case-control study, we included DFI episodes treated with a combined surgical-antibiotic approach.

We included 721 DFI episodes, 537 with osteomyelitis (DFO). CF occurred in 191 (26.5%) and MF in 42 (5.8%) episodes. Multivariate Cox regression analysis showed that a short ABT of 8-21 days (hazard ratio [HR] 0.4; 95% CI 0.2-0.7) was inversely associated with CF. This was also applicable for IV ABT with relatively short durations of 2-7 days (HR 0.5; 95% CI 0.3-0.8) or 8-14 days (HR 0.6; 95% CI 0.4-0.9). We failed to detect a minimal threshold of total or IV ABT predictive for CF or MF.

Compared with total ABT of more than 84 days and IV therapy of more than 14 days, shorter total and IV ABT yielded no enhanced risk of CF or MF. Considering the "bias by indication" that is inherent to retrospective DFI studies, the best study design concerning the duration of ABT would be a stratified, prospective randomized trial, which is currently under way in our medical center.

Diabetic foot infection is a frequent complication in long-standing diabetes mellitus. For antimicrobial therapy of this infection, both the optimal duration and the route of administration are often based more on expert opinion than on published evidence. We reviewed the scientific literature, specifically seeking prospective trials, and aimed at addressing two clinical issues: (1) shortening the currently recommended antibiotic duration and (2) using oral (rather than parenteral) therapy, especially after the patient has undergone debridement and revascularization. We also reviewed some older key articles that are critical to our understanding of the treatment of these infections, particularly with respect to diabetic foot osteomyelitis. Our conclusion is that the maximum duration of antibiotic therapy for osteomyelitis should be no more than to 4-6 weeks and might even be shorter in selected cases. In the future, in addition to conducting randomized trials and propagating national and international guidance, we should also explore innovative strategies, such as intraosseous antibiotic agents and bacteriophages.