title: The safety and efficacy of linezolid and daptomycin as an additive in Optisol-GS against methicillin-resistant Staphylococcus aureus.
abstract: OBJECTIVE
  To evaluate the efficacy of adding either linezolid or daptomycin to Optisol-GS donor storage medium in reducing methicillin-resistant Staphylococcus aureus (MRSA) contamination of donor corneas.
  
  
  METHODS
  Optisol-GS was supplemented with either linezolid at 2×, 4×, or 10× minimum inhibitory concentration (MIC) or daptomycin and calcium at 5× or 50× MIC. Unsupplemented control groups were also used. Gentamicin-sensitive and gentamicin-resistant isolates of MRSA were added, and vials were refrigerated for 48 hours followed by sampling for viable colony counts immediately upon removal from refrigeration and after warming to room temperature for 3 hours. Safety studies of Optisol-GS supplemented with 50× MIC daptomycin and calcium were performed by evaluating the central corneal thickness and endothelial cell density of the donor cornea. Stability of daptomycin in Optisol-GS at storage was also tested.
  
  
  RESULTS
  No added benefit was observed with linezolid supplementation to Optisol-GS against gentamicin-sensitive MRSA, with reduction in viable colony counts by >90% in all groups. No benefit was observed with linezolid supplementation against gentamicin-resistant MRSA, with the majority of inocula remaining viable in all groups. Viable counts of gentamicin-sensitive MRSA and gentamicin-resistant MRSA were effectively reduced with both 5× MIC and 50× MIC daptomycin supplementation. 50× MIC daptomycin-supplemented Optisol-GS had no appreciable effect on the central corneal thickness or endothelial cell density of the donor cornea and was stable at storage for 14 days.
  
  
  CONCLUSIONS
  The addition of daptomycin to Optisol-GS significantly increases the anti-MRSA activity of the medium without any apparent negative effects on donor corneal tissue.
authors.affiliation: UC Davis Health System Eye Center, University of California, Davis, Sacramento, CA 95817, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Li
authors.forename: Vahid
authors.initials: V
authors.lastname: Feiz
authors.forename: Ana Carolina
authors.initials: AC
authors.lastname: Vieira
authors.forename: David
authors.initials: D
authors.lastname: Davis-Boozer
authors.forename: Christopher
authors.initials: C
authors.lastname: Polage
mesh_terms: D000081:Acetamides / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002809:Chondroitin Sulfates / Q000494:pharmacology*; D015169:Colony Count, Microbial; D045424:Complex Mixtures / Q000494:pharmacology; D003315:Cornea; D016895:Culture Media, Serum-Free; D017576:Daptomycin / Q000494:pharmacology*; D003911:Dextrans / Q000494:pharmacology*; D004355:Drug Stability; D004359:Drug Therapy, Combination; D005839:Gentamicins / Q000494:pharmacology*; D006801:Humans; D000069349:Linezolid; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D009926:Organ Preservation; D019188:Organ Preservation Solutions / Q000494:pharmacology*; D023303:Oxazolidinones / Q000494:pharmacology*; D010865:Pilot Projects; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology; D016896:Treatment Outcome
chemical_list: D000081:Acetamides; D000900:Anti-Bacterial Agents; D045424:Complex Mixtures; D016895:Culture Media, Serum-Free; D003911:Dextrans; D005839:Gentamicins; D019188:Organ Preservation Solutions; D023303:Oxazolidinones; D002809:Chondroitin Sulfates; C075736:Optisol; D000069349:Linezolid; D017576:Daptomycin