Role of bone biopsy and deep tissue culture for antibiotic stewardship in diabetic foot osteomyelitis

Diabetic Foot Osteomyelitis Undergoing Amputation: Epidemiology and Prognostic Factors for Treatment Failure

Background

When treating diabetic foot osteomyelitis (DFO), it remains difficult to determine the presence of residual infection and the optimal treatment after bone resection. In this study, we aimed to investigate the clinical characteristics of and prognostic factors in patients with DFO undergoing amputation.

Methods

This retrospective study involved 101 patients with DFO who underwent amputation. Data on their demographics, clinical characteristics, tissue culture, and surgery type were collected. Patients were grouped according to primary closure status and clinical outcome postamputation. A good outcome was defined as a successful complete remission, characterized by the maintenance of complete wound healing with no sign of infection at 6 months postamputation. Multivariate logistic regression analysis was performed. Outcomes according to surgery type were also analyzed.

Results

Staphylococcus aureus (17%) and Pseudomonas species (14%) were the most prevalent pathogens. Gram-negative bacteria were isolated from 62% of patients. In patients with primary closure, hemodialysis and ankle brachial index (ABI) <0.6 were associated with poor outcomes. In patients with DFO, ABI <0.6 was the only prognostic factor associated with treatment failure. Antimicrobial stewardship allows patients who underwent major amputation to reduce the duration of antibiotic therapy compared to those after minor amputation, although it did not contribute to reducing mortality.

Conclusions

Peripheral artery disease and hemodialysis were associated with poor outcomes despite radical resection of the infected bone. Vigilant monitoring after amputation and antimicrobial stewardship implemented based on microbiological epidemiology, prognostic factors, and the type of surgery are important. A multidisciplinary team could assist in these activities to ensure treatment success.

The Global Prevalence of Methicillin-Resistant Staphylococcus Aureus in Patients with Diabetic Foot Ulcers: A Systematic Review and Meta-Analysis

Objective

Diabetic foot ulcer (DFU) frequently leads to infections, with infected DFUs being a common cause of amputation. Infection by methicillin-resistant Staphylococcus aureus (MRSA) notably increases the necessity for amputation and surgical debridement in affected individuals. Consequently, determining the prevalence and trends of MRSA in patients with DFU is of critical importance. This study aimed to assess the global prevalence and to identify trends in the occurrence of MRSA in tissue or wound swab samples from DFU patients.

Methods

We conducted a comprehensive literature search across PubMed, Embase, Scopus, and Ovid, spanning from the inception of these databases to July 2023, imposing no language restrictions. The inclusion criteria required that the studies report on 30 or more patients with DFU. Additionally, we categorized our analysis based on geographic region, publication date, and the economic status of the patient's domicile. Our primary endpoint was to ascertain the prevalence of MRSA in DFUs. This systematic review has been registered at (https://www.crd.york.ac.uk/prospero/), with the identifier CRD 42023444360.

Results

Our analysis encompassed 40 studies involving 12,924 patients across 20 countries. We found that the overall prevalence of MRSA in DFU was 17% (95% Confidence Interval [CI] 0.14-0.20). Regional prevalence varied significantly: in South America, it was 61% (95% CI 0.46-0.76), in North America 20% (95% CI 0.12-0.27), in Europe 19% (95% CI 0.14-0.25), in Africa 13% (95% CI 0.06-0.20), and in other subgroups 11% (95% CI 0.08-0.15). The prevalence of MRSA in DFUs also differed according to the economic status of the countries: 19% (95% CI 0.15-0.23) in high-income countries, 24% (95% CI 0.1-0.37) in upper-middle-income countries, 11% (95% CI 0.07-0.15) in lower-middle-income countries, and 20% (95% CI 0.13-0.27) in low-income countries. Notably, there has been a decline in MRSA prevalence, from 25% before 2010 to 9% thereafter.

Conclusion

This meta-analysis reveals a decreasing yet still significant global prevalence of MRSA in DFUs. This trend has important implications for antimicrobial resistance and underscores the need for developing targeted programs focusing on infection prevention and exploring alternative therapeutic strategies.

Concordance of bone culture and deep tissue culture during the operation of diabetic foot osteomyelitis and clinical characteristics of patients

PURPOSE

To retrospectively analyze the concordance of bacterial culture between bone tissue and deep soft tissue in diabetic foot osteomyelitis (DFO) patients and clinical characteristics of patients.

METHODS

This study collected samples from 155 patients with suspected DFO (who required amputation after clinical evaluation). Bacterial culture and drug susceptibility tests were performed on the patients' deep soft tissue and bone tissue, and the consistency between the two was compared. In addition, the differences among DFO patients with different degrees of infection were compared classified by the PEDIS classifications.

RESULTS

Among the 155 patients diagnosed with DFO, the positive rate of bone culture was 78.7% (122/155). This study cultured 162 strains, including 73 Gram-positive bacteria, 83 Gram-negative bacteria, and 6 fungi. Staphylococcus aureus (33 strains) was the most common bacteria. The overall agreement between bone culture and tissue culture was 42.8%, with Staphylococcus aureus and Enterobacteria having the best (64.3%) and least agreements (27.3%), respectively. The drug sensitivity results in bone culture showed that Staphylococcus aureus was the main Gram-positive bacteria. The bacteria were sensitive to linezolid and vancomycin. Proteus mirabilis was the main Gram-negative bacteria. These were more sensitive than biapenem and piperacillin/tazobactam. Fungi were more sensitive to voriconazole and itraconazole.

CONCLUSION

The culture results of deep soft tissues near the bone cannot accurately represent the true pathogen of DFO. For DFO patients, bone culture should be taken as much as possible, and appropriate antibiotics should be selected according to the drug susceptibility results.