Infection is among the most consequential complications of diabetic foot ulceration, and antimicrobial resistance complicates its management. Methicillin-resistant Staphylococcus aureus (MRSA) and other multidrug-resistant organisms (MDROs) are associated with longer treatment courses, more difficult empirical decisions, and a higher burden of care. Understanding how common resistant organisms are, and who is most likely to carry them, helps clinicians and patients interpret culture results and treatment choices.
How Common Is MRSA in Diabetic Foot Ulcers?
A 2024 systematic review and meta-analysis by Zhou and colleagues, published in Diabetes, Metabolic Syndrome and Obesity, pooled 40 studies covering 12,924 patients with diabetic foot ulcers across 20 countries. The pooled MRSA prevalence was approximately 17%. Prevalence varied considerably by region, with estimates of about 20% in North America, 19% in Europe, 13% in Africa, and a markedly higher figure of 61% in South America. The authors also reported a decline over time, from about 25% in studies conducted before 2010 to roughly 9% in more recent data, although the published confidence intervals and some subgroup figures were not entirely consistent within the paper, so these estimates are best viewed as approximate.
An earlier meta-analysis by Macdonald and colleagues in BMC Infectious Diseases (2021) reviewed 112 studies including 16,159 patients with diabetic foot infection. S. aureus, Pseudomonas species, and Escherichia coli were among the most frequently isolated organisms, and about 18% of S. aureus isolates were methicillin-resistant. This figure describes the share of S. aureus isolates that were resistant, not the proportion of all patients affected. The review also noted geographic and economic patterns: gram-negative organisms were more common in lower-income settings, and gram-positive organisms in higher-income settings.
Who Is Most Likely to Harbour Resistant Organisms?
Single-centre data illustrate how common resistance can be in a hospitalized population. In a retrospective study of 147 patients with type 2 diabetes and foot ulcers (Guo and colleagues, PeerJ, 2023), 71 patients (48.3%) had at least one multidrug-resistant organism, and S. aureus accounted for nearly half of the resistant isolates, followed by E. coli and Pseudomonas aeruginosa. In multivariable analysis, previous antimicrobial exposure (odds ratio about 6.9), a neuroischemic wound (odds ratio about 21.6), and concurrent osteomyelitis (odds ratio about 3.6) were associated with MDRO infection. Because this was a single-centre retrospective study with wide confidence intervals, it should be read as hypothesis-supporting rather than definitive.
The Zhou meta-analysis discussion points to a similar set of themes drawn from the wider literature: chronic ulcers, chronic kidney disease, prolonged or inappropriate antibiotic use, prior hospitalization, and nasal MRSA carriage have all been linked to MRSA infection. These associations come from observational research and do not establish causation.
Implications for Diagnosis and Antibiotic Selection
Two practical points follow from this evidence. First, resistance patterns differ substantially by region and by care setting, so local antibiogram data matter more than any single global estimate. Second, clinical features such as a prior history of resistant infection, recent antibiotic exposure, chronic or deep wounds, and bone involvement increase the likelihood that a resistant organism is present. The joint IWGDF and Infectious Diseases Society of America guidance on diabetic foot infection emphasizes that antibiotics should be reserved for clinically infected wounds, that deep tissue samples (rather than superficial swabs) are preferred for culture, and that therapy should be narrowed according to culture and sensitivity results. Antibiotics should be chosen to cover likely pathogens, including MRSA where risk factors or local prevalence warrant it, rather than being broadened routinely.
Prolonged courses and unnecessary broad-spectrum use are themselves risk factors for resistance, which creates a cycle that careful stewardship aims to interrupt. Surgical debridement and drainage of infected or necrotic tissue, and assessment of perfusion, remain central to infection control and reduce reliance on antibiotics alone.
Limitations of the Current Evidence
Most published data are observational, microbiological definitions and sampling methods vary between studies, and prevalence estimates are heterogeneous. Pooled figures may also reflect differences in patient populations, from outpatients with mild infection to hospitalized patients with severe infection or osteomyelitis. Findings from one setting should therefore not be applied unquestioningly to another.
Key Takeaways
MRSA is present in roughly one in six diabetic foot ulcers in pooled analyses, with wide regional variation and a possible decline over time. Multidrug-resistant organisms are more likely in patients with prior antibiotic exposure, ischaemic or chronic wounds, and bone infection. Appropriate sampling, local resistance data, targeted therapy, and timely debridement form the evidence-based foundation for managing infection in the diabetic foot.
References
- Zhou S, Hu X, Wang Y, Fei W, Sheng Y, Que H. The global prevalence of methicillin-resistant Staphylococcus aureus in patients with diabetic foot ulcers: a systematic review and meta-analysis. Diabetes Metab Syndr Obes. 2024;17:563-574.
- Macdonald KE, Boeckh S, Stacey HJ, Jones JD. The microbiology of diabetic foot infections: a meta-analysis. BMC Infect Dis. 2021;21:770.
- Guo et al. Distribution of multidrug-resistant bacterial infections in diabetic foot ulcers and risk factors for drug resistance: a retrospective analysis. PeerJ. 2023;11:e16162.
- International Working Group on the Diabetic Foot and Infectious Diseases Society of America. Guidelines on the diagnosis and treatment of diabetes-related foot infections. 2023.
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