Browsing by Subject "Magnetic Fields"
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Item Employing Alternating Magnetic Fields for Biofilm Destruction(2020-01-21) Vachon, M. Jonathan; Wang, Qi; Pybus, Christine; Shaikh, Sumbul; Chopra, Rajiv; Greenberg, DavidBACKGROUND: 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.Item The Invisible Force: Optimizing Novel Approaches in Anesthesiology and Infectious Diseases(2022-05-01T05:00:00.000Z) Vachon, Matthew Jonathan; Marull, Javier H.; Huth, James F.; Lin, MitchellThis work encompasses a theme revolving the OR: specifically, preoperatively, perioperatively, and postoperatively. Chapter 1 describes a novel method whereby biofilm is destroyed using Alternating Magnetic Fields (AMF). Using S. aureus grown on steel washers to simulate prosthetic joints, we were able to intermittently deliver 3s pulses for 15, 30, or 60 minutes to reduce bacterial load. Combined treatment with AMF and ceftriaxone (or linezolid) showed a 5-log decrease in bacterial load after 24 hours, whereas singular treatment with AMF or abx alone showed total regrowth or moderate decrease in bacterial load respectively. Chapter 2 describes a meta-analysis conducted to assess the safety and efficiency of sugammadex versus neostigmine as neuromuscular blockade (NMB) reversal agents. Neostigmine has been implemented in ORs for many years, but has disadvantages to using neostigmine including autonomic dysfunction like bradycardia and post-operative nausea & vomiting (PONV), and the necessity to administer the drug at the correct time due to its lag time in effect. Sugammadex appears to circumnavigate these problems, but the literature is still not definitive. We performed a meta-analysis that showed sugammadex as having a milder side effect profile compared to neostigmine with reduction in pneumonia (RR = 0.593, 95% CI (0.361, 0.671) and bradycardia (RR = 0. 535, 95% CI (0.424, 0.675), higher PONV risk (RR = 1.21, 95% CI (1.05, 1.39)), and with faster turnaround times. Chapter 3 describes a survey sent out to ambulatory surgical centers (ASC) on management of patients with obstructive sleep apnea (OSA). The need for a CPAP device in the immediate postoperative period at ambulatory surgical centers remains controversial because these ambulatory patients are healthier and have fewer complications. Only 59.7% of ASCs required their patients to bring their CPAP devices on the day of surgery, and 25.37% reported using a CPAP machine postoperatively within the past 2 years, with the highest CPAP usage at one facility being 20 times in that 2-year period. Studies further in-depth are necessary to assess postoperative complications that require a CPAP device to determine the urgency of ASCs implementing SAMBA's recommendations.Item [News](1984-04-03) Williams, AnnItem Non-Invasive Eradication of Biofilm on Metal Implants Using Alternating Magnetic Fields (AMF) and Antibiotics(August 2021) Wang, Qi; Madhuranthakam, Ananth; Chopra, Rajiv; Greenberg, David; Lewis, Matthew Allen; Fiolka, RetoHundreds of thousands of human implant procedures require surgical revision each year due to infection. Infections are difficult to treat with conventional antibiotics due to the formation of biofilm on the implant surface. Our group is developing a non-invasive method to eliminate biofilm on metal implants using alternating magnetic fields (AMF), utilizing the physical principle of electromagnetic induction. The aims of this dissertation are to establish exposure parameters for biofilm elimination in the presence and absence of antibiotics, the development of treatment strategies, and investigation the mechanism of AMF towards biofilm. First, the elimination of biofilm on metal implant using intermittent alternating magnetic field (iAMF) and antibiotics was studied, showing iAMF and antibiotics are synergistic in their biofilm reducing capability. For Pseudomonas aeruginosa biofilm, bacterial burden was reduced > 3 log with iAMF and ciprofloxacin after 24 h compared with either treatment alone. This additional treatment effect was also found on Staphylococcus aureus. iAMF and antibiotic efficacy was seen across various iAMF settings, including different iAMF target temperatures, dose durations, and dosing intervals. Initial mechanistic studies revealed membrane disruption as one factor important for AMF enhanced antibacterial activity in the biofilm. Then, the impact factors generated by AMF, heat and electric current, to metal implants were studied separately. A mathematic model was built to describe the response of biofilm to heat based on Arrhenius equation in order to study the responses of various strains to heat. Also, the synergistic effect of heat and antibiotics was observed towards biofilm elimination at various treatment temperatures. Finally, the effect of alternating electric current was studied using a burst AMF (bAMF) strategy, in which negligible heating was produced. For Pseudomonas aeruginosa biofilm, bAMF was able to eliminate biofilm in combination with antibiotics for surface current densities ranging from 99 to 297 A/cm2. This effect was also observed with bAMF and linezolid or rifampin in Staphylococcus aureus but with higher surface current densities required to achieve the same level of biofilm reduction. The results of this study support the use of AMF to reduce biofilm on infected metal implants. The effect can be achieved through both thermal and electrical pathways, or a combination of both. When combined with antibiotics, the effect is amplified and can regularly achieve biofilm eradication. In the future, the results of this thesis can be used to define operating parameters for the non-invasive treatment of infected metal implants.Item Thermal Eradication of Prosthetic Joint Associated Bacteria(2018-01-23) Kreutz, Kasey; Saini, Reshu; Chopra, Rajiv; Greenberg, DavidPURPOSE: As with other medical implants, prosthetic joints provide a hospitable surface for bacterial adherence and biofilm formation. We are developing a non-invasive thermal technique to destroy biofilm on the metal surfaces of prosthetic joints using alternating magnetic fields (AMF). One hypothesized benefit of AMF therapy is that it could be used in conjunction with traditional antibiotics to produce a synergistic bactericidal effect. The purpose of this study is to characterize the thermal sensitivity of bacteria in the presence of antibiotics to aid in the development of appropriate parameters for AMF dosing. METHODS: Planktonic solutions of Pseudomonas aeruginosa were thermally shocked in heating blocks with and without minimum inhibitory concentrations of ciprofloxacin. Bacterial solutions were plated on blood agar at intervals throughout the experiment to create a time-kill curve of the combined effects of heat shock therapy and ciprofloxacin. RESULTS: A single 10-minute dose of 55°C thermal shock reduced bacterial concentrations by 1.47-log CFU/mL, but subsequent incubation allowed bacteria to quickly reach and surpass original starting concentrations. Ciprofloxacin alone achieved a 3.78-log reduction within six hours and prevented significant regrowth during 24 hours of incubation. In combination, thermal shock and antibiotic achieved a 6.20-log reduction within 24 hours. After 24 hours allowing for regrowth, combination therapy produced superior bactericidal effect when compared to antibiotic or heat shock alone. When multiple doses of heat were applied in conjunction with antibiotic exposure, a step-down effect over time was observed as the log reduction achieved by each successive heat shock was either preserved or accentuated by the simultaneous inhibitory activity of the antibiotic. CONCLUSION: The results of this study demonstrate that the bactericidal effects of thermal shock are enhanced by the addition of antibiotics, and appear to show a promising synergistic benefit over either treatment being used alone. Future steps will focus on applying combination therapy to biofilm in an AMF coil in order to determine how dose requirements may differ.