Biofilm and the effect of sonication in a chronic Staphylococcus epidermidis orthopedic in vivo implant infection model
Abstract Background In diagnosing chronic orthopedic implant infections culture of sonicate represents a supplement to tissue cultures. However, the extent to which biofilm forms on implant surfaces and the degree of dislodgement of bacteria by sonication remains unclear. In this in vivo study using...
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| Format: | Article |
| Language: | English |
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BMC
2024-12-01
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| Series: | Journal of Orthopaedic Surgery and Research |
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| Online Access: | https://doi.org/10.1186/s13018-024-05309-3 |
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| author | Erik Thorvaldsen Sandbakken Erling Høyer Eivind Witsø Caroline Krogh Søgaard Alberto Díez-Sánchez Linh Hoang Tina Strømdal Wik Kåre Bergh |
| author_facet | Erik Thorvaldsen Sandbakken Erling Høyer Eivind Witsø Caroline Krogh Søgaard Alberto Díez-Sánchez Linh Hoang Tina Strømdal Wik Kåre Bergh |
| author_sort | Erik Thorvaldsen Sandbakken |
| collection | DOAJ |
| description | Abstract Background In diagnosing chronic orthopedic implant infections culture of sonicate represents a supplement to tissue cultures. However, the extent to which biofilm forms on implant surfaces and the degree of dislodgement of bacteria by sonication remains unclear. In this in vivo study using a low bacterial inoculum, we aimed to determine whether a variable effect of sonication could be observed in a standardized in vivo model. Materials and Methods Seven Wistar rats underwent surgery with intramuscular implantation of two bone xenograft implants, each containing two steel plates. The grafts were inoculated with approximately 500 colony forming units (CFU) of Staphylococcus epidermidis ATCC 35984. After 20 days the rats were sacrificed, and the steel plates were removed from the bone grafts. Epifluorescence microscopy and scanning electron microscopy (SEM) were used to visualize biofilm formation and dislodgement on the plate surfaces. In addition to cultures of sonicate, a quantitative S. epidermidis specific PCR was developed for enumeration of bacteria. Results A chronic, low-grade implant infection was successfully established, with all animals remaining in good health. All infected bone graft implants yielded abundant growth of S. epidermidis, with a median of 3.25 (1.6–4.6) × 10⁷ CFU per/graft. We were unable to distinguish infected plates from negative controls using epifluorescence microscopy. On infected plates small colonies of staphylococci were identified by SEM. The number of bacteria detected in the sonicate was low with 500 (100–2400) CFU/plate and 475 (140–1821) copies/plate by qPCR. The difference in area covered by fluorescent material before and after sonication was 10.1 (5.7–12.3) %, p = 0.018. Conclusion Despite the pronounced infection in the surrounding tissue, only few bacteria were detected on the surface of the steel implants. This is evident from the minimal findings by SEM before sonication, as well as the very low CFU counts and DNA copies in the sonicate. Sonication did not show variable effectiveness, indicating it is a valuable addition to, but not a replacement for biopsy cultures in cases of implant-associated infections with low-virulence microorganisms. |
| format | Article |
| id | doaj-art-59ea5e43b6d643fe95b543b8e45bbc46 |
| institution | OA Journals |
| issn | 1749-799X |
| language | English |
| publishDate | 2024-12-01 |
| publisher | BMC |
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| series | Journal of Orthopaedic Surgery and Research |
| spelling | doaj-art-59ea5e43b6d643fe95b543b8e45bbc462025-08-20T02:31:04ZengBMCJournal of Orthopaedic Surgery and Research1749-799X2024-12-0119111410.1186/s13018-024-05309-3Biofilm and the effect of sonication in a chronic Staphylococcus epidermidis orthopedic in vivo implant infection modelErik Thorvaldsen Sandbakken0Erling Høyer1Eivind Witsø2Caroline Krogh Søgaard3Alberto Díez-Sánchez4Linh Hoang5Tina Strømdal Wik6Kåre Bergh7Department of Orthopedic Surgery, St. Olavs HospitalDepartement of Medical Microbiology, St. Olavs HospitalDepartment of Orthopedic Surgery, St. Olavs HospitalDepartment of Clinical and Molecular Medicine, NTNUCellular and Molecular Imaging Core Facility (CMIC), NTNUCellular and Molecular Imaging Core Facility (CMIC), NTNUDepartment of Orthopedic Surgery, St. Olavs HospitalDepartement of Medical Microbiology, St. Olavs HospitalAbstract Background In diagnosing chronic orthopedic implant infections culture of sonicate represents a supplement to tissue cultures. However, the extent to which biofilm forms on implant surfaces and the degree of dislodgement of bacteria by sonication remains unclear. In this in vivo study using a low bacterial inoculum, we aimed to determine whether a variable effect of sonication could be observed in a standardized in vivo model. Materials and Methods Seven Wistar rats underwent surgery with intramuscular implantation of two bone xenograft implants, each containing two steel plates. The grafts were inoculated with approximately 500 colony forming units (CFU) of Staphylococcus epidermidis ATCC 35984. After 20 days the rats were sacrificed, and the steel plates were removed from the bone grafts. Epifluorescence microscopy and scanning electron microscopy (SEM) were used to visualize biofilm formation and dislodgement on the plate surfaces. In addition to cultures of sonicate, a quantitative S. epidermidis specific PCR was developed for enumeration of bacteria. Results A chronic, low-grade implant infection was successfully established, with all animals remaining in good health. All infected bone graft implants yielded abundant growth of S. epidermidis, with a median of 3.25 (1.6–4.6) × 10⁷ CFU per/graft. We were unable to distinguish infected plates from negative controls using epifluorescence microscopy. On infected plates small colonies of staphylococci were identified by SEM. The number of bacteria detected in the sonicate was low with 500 (100–2400) CFU/plate and 475 (140–1821) copies/plate by qPCR. The difference in area covered by fluorescent material before and after sonication was 10.1 (5.7–12.3) %, p = 0.018. Conclusion Despite the pronounced infection in the surrounding tissue, only few bacteria were detected on the surface of the steel implants. This is evident from the minimal findings by SEM before sonication, as well as the very low CFU counts and DNA copies in the sonicate. Sonication did not show variable effectiveness, indicating it is a valuable addition to, but not a replacement for biopsy cultures in cases of implant-associated infections with low-virulence microorganisms.https://doi.org/10.1186/s13018-024-05309-3BiofilmAnimal modelImplant infection modelStaphylococcus epidermidisSonicationPCR |
| spellingShingle | Erik Thorvaldsen Sandbakken Erling Høyer Eivind Witsø Caroline Krogh Søgaard Alberto Díez-Sánchez Linh Hoang Tina Strømdal Wik Kåre Bergh Biofilm and the effect of sonication in a chronic Staphylococcus epidermidis orthopedic in vivo implant infection model Journal of Orthopaedic Surgery and Research Biofilm Animal model Implant infection model Staphylococcus epidermidis Sonication PCR |
| title | Biofilm and the effect of sonication in a chronic Staphylococcus epidermidis orthopedic in vivo implant infection model |
| title_full | Biofilm and the effect of sonication in a chronic Staphylococcus epidermidis orthopedic in vivo implant infection model |
| title_fullStr | Biofilm and the effect of sonication in a chronic Staphylococcus epidermidis orthopedic in vivo implant infection model |
| title_full_unstemmed | Biofilm and the effect of sonication in a chronic Staphylococcus epidermidis orthopedic in vivo implant infection model |
| title_short | Biofilm and the effect of sonication in a chronic Staphylococcus epidermidis orthopedic in vivo implant infection model |
| title_sort | biofilm and the effect of sonication in a chronic staphylococcus epidermidis orthopedic in vivo implant infection model |
| topic | Biofilm Animal model Implant infection model Staphylococcus epidermidis Sonication PCR |
| url | https://doi.org/10.1186/s13018-024-05309-3 |
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