title: The in vitro and in vivo antibacterial characterization of vancomycin and linezolid against vancomycin-susceptible and -resistant enterococci.
abstract: The present study was designed to compare in vitro antibacterial activities of linezolid and vancomycin against vancomycin-susceptible Enterococcus faecalis (VSEF) and vancomycin-resistant enterococci (VRE) isolated in Japan with those of quinupristin-dalfopristin, teicoplanin and minocycline, and the in vitro short time bactericidal activity and the in vivo activities of linezolid and vancomycin against vancomycin-susceptible and -resistant E. faecalis. The MIC90s of linezolid, quinupristin-dalfopristin, vancomycin, teicoplanin and minocycline for VSEF and VRE were both 2 mg/L, both 2 mg/L, 2 and >128 mg/L, 0.25 and >128 mg/L, and both 32 mg/L, respectively. The efficacy of linezolid for mice with bacteraemia caused by VSEF was similar to that of vancomycin, but the elimination ratio of viable organisms from the blood of mice treated with vancomycin was significantly higher than in linezolid-treated and untreated mice at 2 h post-administration, and those of the two groups at 4 and 6 h were significantly higher than in untreated mice. Moreover, linezolid was highly active in mice with bacteraemia caused by vancomycin-resistant E. faecalis because this drug had potent in vitro activity against the organisms. Our results indicate that linezolid is suitable for the treatment of VRE and VSEF bacteraemia, and vancomycin is suitable for VSEF bacteraemia.
authors.affiliation: Department of Microbiology, Toho University School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143, Japan. shuichi@med.toho-u.ac.jp
authors.forename: Shuichi
authors.initials: S
authors.lastname: Miyazaki
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Fujikawa
authors.forename: Intetsu
authors.initials: I
authors.lastname: Kobayashi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Tateda
authors.forename: Keizo
authors.initials: K
authors.lastname: Yamaguchi
mesh_terms: D000081:Acetamides / Q000494:pharmacology*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004353:Drug Evaluation, Preclinical / Q000379:methods; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D000069349:Linezolid; D051379:Mice; D008810:Mice, Inbred C57BL; D008826:Microbial Sensitivity Tests; D023303:Oxazolidinones / Q000494:pharmacology*; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance / Q000502:physiology*
chemical_list: D000081:Acetamides; D000900:Anti-Bacterial Agents; D023303:Oxazolidinones; D014640:Vancomycin; D000069349:Linezolid