Employing Alternating Magnetic Fields for Biofilm Destruction




Vachon, M. Jonathan

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BACKGROUND: Prosthetic Joint Infections (PJI) are a common complication of implant surgery. Due to biofilm formation, treatment is costly, includes weeks of antibiotic therapy, and even total replacement of the prosthesis. However, a non-invasive thermal method of biofilm eradication has recently been developed: using high-frequency alternating magnetic fields (AMF) to destroy biofilm via induction. METHODS: The experiment used Staphylococcus aureus, a prototypic pathogen implicated in PJI. Stainless steel rings were used to mimic prosthetic joints. Biofilms of Methicillin-Sensitive Staphylococcus aureus (UAMS1-lux) were grown on stainless steel rings in a shaking incubator for 24 hours, 110rpm at 37°C, in Tryptic Soy Broth media. The rings were then resuspended in fresh media and incubated for another 24 hours at 110rpm, 37°C. Untreated rings, Antibiotics only, AMF only, and a combination of AMF + Abx were tested. Biofilms in the latter 2 categories underwent 3s pulses of AMF exposure every 5 minutes for 15, 30, or 60 minutes at a target temperature of 65°C every 12 hours for 24 hours. Ceftriaxone (2.0μg/ml) was used for the Abx conditions. Rings were sonicated at the indicated timepoints and colony-forming units (CFU) were determined. RESULTS: A synergistic effect between AMF and antibiotics was seen. At 12 hours, the Abx only and AMF only treatments showed regrowth; however, the combination therapy showed a 2.1-log decrease in biofilm CFU. Similarly, at 24 hours, solo AMF treatment showed total regrowth and Abx only treatment showed modest bactericidal effects (2.1 log reduction). However, combination therapy at 24hr showed a 5.35 log reduction and reached the limit of detection of the assay. Additionally, we are investigating the effects of AMF with Linezolid (2.0 μg/ml). At 24hrs, a 4.3 log reduction in biofilm CFU was observed in the combination treatment, while solo treatments showed total regrowth. CONCLUSIONS: These in vitro results serve as a strong basis for future work on AMF utilization in treatment of PJI. AMF and antibiotics are synergistic in reducing biofilm off metal. The observed bactericidal effects combined with this non-invasive means have wide and significant implications in improving the patient's quality of life as well as improving healthcare costs of PJI treatment.

General Notes

The 58th Annual Medical Student Research Forum at UT Southwestern Medical Center (Tuesday, January 21, 2020, 3-6 p.m., D1.600)
Each year the Medical Student Research Program awards students for the best oral presentation and the best poster presentation as judged by faculty across campus. This author received an award as one of the best poster presentations at this forum.

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Vachon, M. J., Wang, Q., Pybus, C., Shaikh, S., Chopra, R., & Greenberg, D. (2020, January 21). Employing alternating magnetic fields for biofilm destruction. Poster session presented at the 58th Annual Medical Students Research Forum, Dallas, TX. Retrieved from https://hdl.handle.net/2152.5/8271

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