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Lee J, Mashayamombe M, Walsh TP, Kuang BKP, Pena GN, Vreugde S, Cooksley C, Carda-Diéguez M, Mira A, Jesudason D, Fitridge R, Zilm PS, Dawson J, Kidd SP. The bacteriology of diabetic foot ulcers and infections and incidence of Staphylococcus aureus Small Colony Variants. J Med Microbiol 2023; 72. [PMID: 37326607 DOI: 10.1099/jmm.0.001716] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023] Open
Abstract
Introduction. Uninfected diabetes-related foot ulcer (DFU) progression to diabetes-related foot infection (DFI) is a prevalent complication for patients with diabetes. DFI often progresses to osteomyelitis (DFI-OM). Active (growing) Staphylococcus aureus is the most common pathogen in these infections. There is relapse in 40-60 % of cases even when the initial treatment at the DFI stage apparently clears infection.Hypothesis. S. aureus adopts the quasi-dormant Small Colony Variant (SCV) state during DFU and consequently infection, and when present in DFI cases also permits survival in non-diseased tissues as a reservoir to cause relapse.Aim. The aim of this study was to investigate the bacterial factors that facilitate persistent infections.Methodology. People with diabetes were recruited from two tertiary hospitals. Clinical and bacterial data was taken from 153 patients with diabetes (51 from a control group with no ulcer or infection) and samples taken from 102 patients with foot complications to identify bacterial species and their variant colony types, and then compare the bacterial composition in those with uninfected DFU, DFI and those with DFI-OM, of whom samples were taken both from wounds (DFI-OM/W) and bone (DFI-OM/B). Intracellular, extracellular and proximal 'healthy' bone were examined.Results. S. aureus was identified as the most prevalent pathogen in diabetes-related foot pathologies (25 % of all samples). For patients where disease progressed from DFU to DFI-OM, S. aureus was isolated as a diversity of colony types, with increasing numbers of SCVs present. Intracellular (bone) SCVs were found, and even within uninfected bone SCVs were present. Wounds of 24 % of patients with uninfected DFU contained active S. aureus. All patients with a DFI with a wound but not bone infection had previously had S. aureus isolated from an infection (including amputation), representing a relapse.Conclusion. The presence of S. aureus SCVs in recalcitrant pathologies highlights their importance in persistent infections through the colonization of reservoirs, such as bone. The survival of these cells in intracellular bone is an important clinical finding supporting in vitro data. Also, there seems to be a link between the genetics of S. aureus found in deeper infections compared to those only found in DFU.
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Affiliation(s)
- James Lee
- Department of Molecular and Biomedical Sciences, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
- Research Centre for Infectious Disease (RCID), University of Adelaide, Adelaide, South Australia, Australia
- Australian Centre for Antimicrobial Resistance Ecology (ACARE), University of Adelaide, Adelaide, South Australia, Australia
| | - Matipaishe Mashayamombe
- Department of Vascular Surgery, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Tom P Walsh
- School of Clinical Sciences, Faculty of Health, Queensland University of Technology (QUT), Kelvin Grove, Queensland 4059, Australia
| | - Beatrice K P Kuang
- School of Clinical Sciences, Faculty of Health, Queensland University of Technology (QUT), Kelvin Grove, Queensland 4059, Australia
- Discipline of Surgery, Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Guilherme N Pena
- School of Clinical Sciences, Faculty of Health, Queensland University of Technology (QUT), Kelvin Grove, Queensland 4059, Australia
- Discipline of Surgery, Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Sarah Vreugde
- Basil Hetzel Institute for Translational Health Research, Queen Elizabeth Hospital, Adelaide, South Australia, Australia
| | - Clare Cooksley
- Basil Hetzel Institute for Translational Health Research, Queen Elizabeth Hospital, Adelaide, South Australia, Australia
| | - Miguel Carda-Diéguez
- Department of Health and Genomics, Center for Advanced Research in Public Health, FISABIO Institute, Valencia, Province of Valencia, Spain
| | - Alex Mira
- Department of Health and Genomics, Center for Advanced Research in Public Health, FISABIO Institute, Valencia, Province of Valencia, Spain
| | - David Jesudason
- Endocrinology Unit, Queen Elizabeth Hospital, Adelaide, South Australia, Australia
| | - Robert Fitridge
- School of Clinical Sciences, Faculty of Health, Queensland University of Technology (QUT), Kelvin Grove, Queensland 4059, Australia
- Discipline of Surgery, Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Peter S Zilm
- Adelaide Dental School, University of Adelaide, Adelaide, South Australia, Australia
| | - Joseph Dawson
- School of Clinical Sciences, Faculty of Health, Queensland University of Technology (QUT), Kelvin Grove, Queensland 4059, Australia
- Discipline of Surgery, Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Stephen P Kidd
- Department of Molecular and Biomedical Sciences, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
- Research Centre for Infectious Disease (RCID), University of Adelaide, Adelaide, South Australia, Australia
- Australian Centre for Antimicrobial Resistance Ecology (ACARE), University of Adelaide, Adelaide, South Australia, Australia
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