Oxazolidinones, a New ClassofSynthetic Antibacterial Agents: InVitro andInVivoActivities ofDuP105andDuP721

strains. TheMICsfor90%ofthestrains (MIC90s) against staphylococcal isolates were 1 to4,ug/ml forDuP721and4to16,ug/ml forDuP105, compared with1to2jig/ml forvancomycin, 0.5,ug/ml forciprofloxacin, and2to>16,ug/ml forimipenem. TheMIC90s against groupD streptococci were 4,ug/ml forDuP721,16,ug/ml forDuP105, and2,ug/ml forvancomycin, ciprofloxacin, andimipenem. MIC90s against B.fragilis isolates were4,ug/ml forDuP721,16,ug/ml forDuP105, and8,ug/ml forcefoxitin. DuP721and DuP105administered byeither theoral ortheparenteral route were protective against staphylococcal and streptococcal infections inmice. The50%effective doses were2to10mg/kg forDuP721, 9to23mg/kg forDuP 105,and2to12mg/kgforvancomycin. Theseresults indicate thatfurther studies ofcompounds ofthe oxazolidinone series arewarranted.