Finding the Optimal Tobramycin and Vancomycin Exposure to Remove Biofilms on Muscle and Bone Tissue In Vitro
European Journal of Molecular & Clinical Medicine,
2023, Volume 10, Issue 4, Pages 458-465
AbstractChronic orthopaedic infections are brought on by bacterial biofilms. Without adjuvant local antimicrobials, surgical debridement to remove biofilm may be inefficient because undiscovered biofilm pieces may stay in the site and reactivate the infection if left untreated. The levels and length of antibiotic exposure required to remove bacteria from clinical biofilms are still mostly unknown. For bacterial biofilms formed on bone and muscle in vitro, we calculated the minimal biofilm eradication concentration (MBEC) of tobramycin and vancomycin.
Method: CFU counts were used to characterizing the pathogen biofilms of S. aureus, S. epidermidis, E. faecalis, P. aeruginosa, and E. coli, which are commonly encountered in musculoskeletal illnesses. Serial log2 dilutions (4000-31.25 µg/mL) of tobramycin, vancomycin or a 1:1 mixture of both medicines were applied to tissue specimens covered in biofilm for 5, 25, or 70 hours. To test bacterial survival after antibiotic exposure, tissues were subcultured. For each pathogen-antimicrobial-exposure-time combination, the MBEC was determined as the concentration at which there were no surviving bacteria.
Results: On tissue, all infections that were tested developed biofilm. Using MBEC on muscle or bone, tobramycin/vancomycin (1:1) was the most effective antibacterial treatment, often in the range of 200-750 µg/mL with 25 or 70hr exposure. For 53.2% of biofilms between 5 and 25 hours, 53.2% of biofilms between 25 and 70 hours, and for 76.6% of biofilms between 5 and 70 hours, MBEC decreased with exposure duration. In comparison to equivalent MBECs in muscle tissue, MBECs on bone were substantially greater (p <0.04). The majority of the time, tissue MBECs were lower than MBECs for the same pathogens on polystyrene tissue-culture plates that had previously been published.
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