Induction heating combined with antibiotics or SAAP-148 effectively reduces biofilm-embedded Staphylococcus aureus on a fracture-related implant mimic
Aims: Fracture-related infections and the associated treatment failure burden our society and healthcare system significantly. As an alternative approach, we investigated the effect of non-contact induction heating (NCIH) against Staphylococcus aureus within mature biofilms. In addition, we assesse...
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The British Editorial Society of Bone & Joint Surgery
2025-05-01
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| Series: | Bone & Joint Research |
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| Online Access: | https://online.boneandjoint.org.uk/doi/epdf/10.1302/2046-3758.145.BJR-2024-0341.R1 |
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| author | Marielle Verheul Anne A. Wagenmakers Rob G. H. H. Nelissen Peter H. Nibbering Bart G. Pijls |
| author_facet | Marielle Verheul Anne A. Wagenmakers Rob G. H. H. Nelissen Peter H. Nibbering Bart G. Pijls |
| author_sort | Marielle Verheul |
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| description | Aims: Fracture-related infections and the associated treatment failure burden our society and healthcare system significantly. As an alternative approach, we investigated the effect of non-contact induction heating (NCIH) against Staphylococcus aureus within mature biofilms. In addition, we assessed the ability of antibiotics, the antimicrobial peptide SAAP-148, and bacteriophage (phage) ISP to enhance the efficacy of NCIH, thereby allowing the use of lower temperatures during NCIH. Methods: Clinical isolates of methicillin-resistant and methicillin-sensitive S. aureus (methicillin-resistant S. aureus (MRSA), methicillin-sensitive S. aureus (MSSA)) were cultured for seven days on Ti-6Al-7Nb (mimicking fracture plates) discs to obtain mature biofilms. Biofilms were exposed to 60°C to 80°C NCIH. In addition, biofilms were sequentially exposed to 60°C to 70°C NCIH and rifampicin/ciprofloxacin, SAAP-148, or phage ISP. Biofilm-embedded bacteria were harvested by sonication to determine the bacterial load and visualized by confocal microscopy (LIVE/DEAD). Results: NCIH to 60°C, 70°C, and 80°C reduced biofilm-embedded MRSA and MSSA by 2.3-log, 4.9-log, 5.5-log, and 1.1-log, 3.4-log, and 6.6-log CFU/ml, respectively. LIVE/DEAD staining revealed NCIH-induced bacterial cell death throughout the biofilm layers. The sequential combination of rifampicin/ciprofloxacin at 10 µg/ml and 1,280 µg/ml (MRSA) or 156 µg/l and 64 µg/ml (MSSA) and 70°C NCIH synergistically reduced biofilm-embedded bacteria by 2.7-log and 3.7-log CFU/ml, respectively, while the alternating exposure order reduced bacterial counts by -0.1 and 1.7-log CFU/ml. SAAP-148 at 51.2 µM followed by 70°C NCIH further diminished biofilm-embedded MRSA and MSSA by 2.3-log and 1.5-log CFU/ml, respectively. No significant reductions were observed for NCIH combined with phage ISP compared to these treatments alone. Conclusion: NCIH effectively reduced biofilm-embedded S. aureus on Ti-6Al-7Nb in a heat-dependent fashion. Rifampicin/ciprofloxacin and SAAP-148, but not phage ISP, enhanced the efficacy of NCIH. Antibiotic exposure at suboptimal concentrations followed by NCIH was more effective than vice versa, suggesting that the application of this approach might be most suitable in clinical situations where antibiotic treatment has already started. Cite this article: Bone Joint Res 2025;14(5):485–494. |
| format | Article |
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| language | English |
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| spelling | doaj-art-dbc9a1bfa559485da480f252569fb24e2025-08-20T02:34:03ZengThe British Editorial Society of Bone & Joint SurgeryBone & Joint Research2046-37582025-05-0114548549410.1302/2046-3758.145.BJR-2024-0341.R1Induction heating combined with antibiotics or SAAP-148 effectively reduces biofilm-embedded Staphylococcus aureus on a fracture-related implant mimicMarielle Verheul0Anne A. Wagenmakers1Rob G. H. H. Nelissen2Peter H. Nibbering3Bart G. Pijls4 Department of Orthopedics, Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands Department of Orthopedics, Leiden University Medical Center, Leiden, Netherlands Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands Department of Orthopedics, Leiden University Medical Center, Leiden, Netherlands Aims: Fracture-related infections and the associated treatment failure burden our society and healthcare system significantly. As an alternative approach, we investigated the effect of non-contact induction heating (NCIH) against Staphylococcus aureus within mature biofilms. In addition, we assessed the ability of antibiotics, the antimicrobial peptide SAAP-148, and bacteriophage (phage) ISP to enhance the efficacy of NCIH, thereby allowing the use of lower temperatures during NCIH. Methods: Clinical isolates of methicillin-resistant and methicillin-sensitive S. aureus (methicillin-resistant S. aureus (MRSA), methicillin-sensitive S. aureus (MSSA)) were cultured for seven days on Ti-6Al-7Nb (mimicking fracture plates) discs to obtain mature biofilms. Biofilms were exposed to 60°C to 80°C NCIH. In addition, biofilms were sequentially exposed to 60°C to 70°C NCIH and rifampicin/ciprofloxacin, SAAP-148, or phage ISP. Biofilm-embedded bacteria were harvested by sonication to determine the bacterial load and visualized by confocal microscopy (LIVE/DEAD). Results: NCIH to 60°C, 70°C, and 80°C reduced biofilm-embedded MRSA and MSSA by 2.3-log, 4.9-log, 5.5-log, and 1.1-log, 3.4-log, and 6.6-log CFU/ml, respectively. LIVE/DEAD staining revealed NCIH-induced bacterial cell death throughout the biofilm layers. The sequential combination of rifampicin/ciprofloxacin at 10 µg/ml and 1,280 µg/ml (MRSA) or 156 µg/l and 64 µg/ml (MSSA) and 70°C NCIH synergistically reduced biofilm-embedded bacteria by 2.7-log and 3.7-log CFU/ml, respectively, while the alternating exposure order reduced bacterial counts by -0.1 and 1.7-log CFU/ml. SAAP-148 at 51.2 µM followed by 70°C NCIH further diminished biofilm-embedded MRSA and MSSA by 2.3-log and 1.5-log CFU/ml, respectively. No significant reductions were observed for NCIH combined with phage ISP compared to these treatments alone. Conclusion: NCIH effectively reduced biofilm-embedded S. aureus on Ti-6Al-7Nb in a heat-dependent fashion. Rifampicin/ciprofloxacin and SAAP-148, but not phage ISP, enhanced the efficacy of NCIH. Antibiotic exposure at suboptimal concentrations followed by NCIH was more effective than vice versa, suggesting that the application of this approach might be most suitable in clinical situations where antibiotic treatment has already started. Cite this article: Bone Joint Res 2025;14(5):485–494.https://online.boneandjoint.org.uk/doi/epdf/10.1302/2046-3758.145.BJR-2024-0341.R1ncihbacteriophage ispantimicrobial peptiderifampicin/ciprofloxacinfristaphylococcus aureusantibioticsbiofilmsrifampicinbacteriamrsapeptidestainingmethicillin-sensitive s. aureusinfections |
| spellingShingle | Marielle Verheul Anne A. Wagenmakers Rob G. H. H. Nelissen Peter H. Nibbering Bart G. Pijls Induction heating combined with antibiotics or SAAP-148 effectively reduces biofilm-embedded Staphylococcus aureus on a fracture-related implant mimic Bone & Joint Research ncih bacteriophage isp antimicrobial peptide rifampicin/ciprofloxacin fri staphylococcus aureus antibiotics biofilms rifampicin bacteria mrsa peptide staining methicillin-sensitive s. aureus infections |
| title | Induction heating combined with antibiotics or SAAP-148 effectively reduces biofilm-embedded Staphylococcus aureus on a fracture-related implant mimic |
| title_full | Induction heating combined with antibiotics or SAAP-148 effectively reduces biofilm-embedded Staphylococcus aureus on a fracture-related implant mimic |
| title_fullStr | Induction heating combined with antibiotics or SAAP-148 effectively reduces biofilm-embedded Staphylococcus aureus on a fracture-related implant mimic |
| title_full_unstemmed | Induction heating combined with antibiotics or SAAP-148 effectively reduces biofilm-embedded Staphylococcus aureus on a fracture-related implant mimic |
| title_short | Induction heating combined with antibiotics or SAAP-148 effectively reduces biofilm-embedded Staphylococcus aureus on a fracture-related implant mimic |
| title_sort | induction heating combined with antibiotics or saap 148 effectively reduces biofilm embedded staphylococcus aureus on a fracture related implant mimic |
| topic | ncih bacteriophage isp antimicrobial peptide rifampicin/ciprofloxacin fri staphylococcus aureus antibiotics biofilms rifampicin bacteria mrsa peptide staining methicillin-sensitive s. aureus infections |
| url | https://online.boneandjoint.org.uk/doi/epdf/10.1302/2046-3758.145.BJR-2024-0341.R1 |
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