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Antimicrobial Agents and Chemotherapy, 04 1996, 839-845, Vol 40, No. 4
GE Zurenko, BH Yagi, RD Schaadt, JW Allison, JO Kilburn, SE Glickman, DK Hutchinson, MR Barbachyn and SJ Brickner
Oxazolidinones make up a relatively new class of antimicrobial agents which
possess a unique mechanism of bacterial protein synthesis inhibition.
U-100592 (S)-N-[[3-[3-fluoro-4-[4-(hydroxyacetyl)-1- piperazinyl]-
phenyl]-2-oxo-5-oxazolidinyl]methyl]-acetamide and U- 100766
(S)-N-[[3-[3-fluoro-4-(4-morpholinyl)phenyl]- 2-oxo-5-
oxazolidinyl]methyl]-acetamide are novel oxazolidinone analogs from a
directed chemical modification program. MICs were determined for a variety
of bacterial clinical isolates; the respective MICs of U-100592 and
U-100766 at which 90% of isolates are inhibited were as follows:
methicillin-susceptible Staphylococcus aureus, 4 and 4 micrograms/ml;
methicillin-resistant S. aureus, 4 and 4 micrograms/ml; methicillin-
susceptible Staphylococcus epidermidis, 2 and 2 micrograms/ml;
methicillin-resistant S. epidermidis, 1 and 2 micrograms/ml; Enterococcus
faecalis, 2 and 4 micrograms/ml; Enterococcus faecium, 2 and 4
micrograms/ml; Streptococcus pyogenes, 1 and 2 micrograms/ml; Streptococcus
pneumoniae, 0.50 and 1 microgram/ml; Corynebacterium spp., 0.50 and 0.50
micrograms/ml; Moraxella catarrhalis, 4 and 4 micrograms/ml; Listeria
monocytogenes, 8 and 2 micrograms/ml; and Bacteroides fragilis, 16 and 4
micrograms/ml. Most strains of Mycobacterium tuberculosis and the
gram-positive anaerobes were inhibited in the range of 0.50 to 2
micrograms/ml. Enterococcal strains resistant to vancomycin (VanA, VanB,
and VanC resistance phenotypes), pneumococcal strains resistant to
penicillin, and M. tuberculosis strains resistant to common antitubercular
agents (isoniazid, streptomycin, rifampin, ethionamide, and ethambutol)
were not cross- resistant to the oxazolidinones. The presence of 10, 20,
and 40% pooled human serum did not affect the antibacterial activities of
the oxazolidinones. Time-kill studies demonstrated a bacteriostatic effect
of the analogs against staphylococci and enterococci but a bactericidal
effect against streptococci. The spontaneous mutation frequencies of S.
aureus ATCC 29213 were <3.8 x 10(-10) and <8 x 10(-11) for U-100592
and U-100766, respectively. Serial transfer of three staphylococcal and two
enterococcal strains on drug gradient plates produced no evidence of rapid
resistance development. Thus, these new oxazolidinone analogs demonstrated
in vitro antibacterial activities against a variety of clinically important
human pathogens.
Copyright © 1996 by the American Society for Microbiology. All rights reserved.
In vitro activities of U-100592 and U-100766, novel oxazolidinone antibacterial agents
Pharmacia & Upjohn, Inc., Kalamazoo, Michigan 49001, USA.
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