title: In vitro evaluation of AZD2563, a new oxazolidinone, tested against unusual gram-positive species.
abstract: The recently introduced oxazolidinone, linezolid, has a spectrum and potency directed against Gram-positive organisms, including antimicrobial-resistant isolates. The newest agent in this class, AZD2563 was tested against uncommonly isolated Gram-positive species to establish the breadth of its spectrum. By reference broth microdilution methods, 120 strains were tested (48 Corynebacterium spp., 10 species; 27 Listeria spp., 2 species; 11 Micrococcus spp., 2 species; 23 Bacillus spp., 3 species; 6 Stomatococcus mucilaginosus and one strain each of 5 other species) against AZD2563 and compared to eight other agents. The AZD2563/linezolid MIC(50;) % inhibited at < or =4 microg/mL were: for corynebacteria (0.25/0.25 microg/mL; 100/100%), Listeria spp. (2/2 microg/mL; 100/100%), Micrococcus spp. (1/1 microg/mL; 100/100%), Bacillus spp. (0.5/1 microg/mL; 100/100%), and S mucilaginosus (0.5/1 microg/mL; 100/100%). Using the MIC(90) values, AZD2563 was slightly more potent than linezolid (two-fold). Only four genus- species groups had AZD2563 MICs of strains at 2 microg/mL (Aerococcus, Leuconostoc, Listeria, Rhodococcus), all other isolates were inhibited by < or = 1 microg/mL. The AZD2563 potency and spectrum versus these rarer species was at least equal to linezolid, including some strains resistant to penicillins, macrolides-lincosamides, and fluoroquinolones.
authors.affiliation: The JONES Group/JMI Laboratories, North Liberty, IA, USA. ronald-jones@jmilabs.com
authors.forename: Ronald N
authors.initials: RN
authors.lastname: Jones
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Biedenbach
authors.forename: Tamara R
authors.initials: TR
authors.lastname: Anderegg
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards; D023303:Oxazolidinones / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D023303:Oxazolidinones; C453362:posizolid