671. Relevance of Levofloxacin-Resistant MRSA and hVISA when utilizing directed antibiotic locks to treat stage 4 biofilm bone and joint infections

Abstract Background Directed antibiotic locks have the potential to treat orthopedic infections due ability bypass specific systemic absorption allowing for higher antimicrobial concentrations. With limiting options biofilm commonly associated with bone and joint infections, our aim is understand further test relevance of utilizing standard MIC values direct therapy. Methods Using previously described assay six unique spa-type (t004, t018, t062, t064, t1340, t008) MRSA isolates, was grown 4, 6, 24hrs at 6 log10 CFU/mL in TSB per CLSI guidance adding dextrose 1.25% promotion. were run using guidance. Planktonic cells removed by irrigation, simulating debridement. 24hr treatment assays, included levofloxacin (5 mg/mL) d5W solution vancomycin NS. Results Levofloxacin definition found be resistant five out isolates (MIC ranging from 1 – 312mcg.mL). However, 16-25,000 times MIC, demonstrated a decrease growth on mature 24-hr established 9-130%. Similarly, heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA), 3000-6000 53-190% growth. Conclusion All produced consistent as tested low or high biofilm-producer when there no present. least 1000X nearly eradicated all biofilm. Our next steps will evaluate if any effect additional antibiotics lock solution. Disclosures Kerry L. LaPlante, Pharm.D., FCCP, FIDSA, FIDP, AbbVie Inc.: Grant/Research Support|Gilead Sciences, Support|Melinta Therapeutics, Inc.,: Support|Merck & Co., Advisor/Consultant|Merck Support|Nabriva Therapeutics US, Support|Ocean Spray Cranberries, Support|Pfizer Pharmaceuticals: Support|Shionogi, Support|Tetraphase Pharmaceuticals.: Support.