title: Susceptibilities of penicillin-susceptible and -resistant strains of Streptococcus pneumoniae to RP 59500, vancomycin, erythromycin, PD 131628, sparfloxacin, temafloxacin, win 57273, ofloxacin, and ciprofloxacin.
abstract: The MICs of four new quinolones, sparfloxacin (AT-4140, CI-978), PD 131628 (the active form of the prodrug CI-990), temafloxacin, and Win 57273, compared with those of ciprofloxacin and ofloxacin were tested against 53 penicillin-susceptible, 35 penicillin intermediate-resistant, and 51 penicillin-resistant pneumococci. Susceptibility to RP 59500, a new streptogramin, was also tested and compared with those to the quinolones, erythromycin, and vancomycin. All MICs were determined by a standardized agar dilution method by using Mueller-Hinton agar supplemented with sheep blood. Quinolone, vancomycin, and RP 59500 susceptibilities were not affected by susceptibility or resistance to penicillin. For Win 57273, the MICs for 50% (MIC50) and 90% (MIC90) of strains tested were 0.015 and 0.03 micrograms/ml, respectively. MIC50S of both sparfloxacin and PD 131628 were 0.25 micrograms/ml, and MIC90S were 0.5 micrograms/ml. The MIC50 of temafloxacin was 0.5 micrograms/ml, and the MIC90 was 1.0 micrograms/ml. By comparison, ofloxacin and ciprofloxacin both yielded MIC50S of 1.0 micrograms/ml and MIC90s of 2.0 micrograms/ml. RP 59500 yielded an MIC50 of 0.5 microgram/ml and an MIC90 of 1.0 microgram/ml and was only 1 doubling dilution less active against 17 erythromycin-resistant strains. Vancomycin was active against all strains (MIC50, 0.25 microgram/ml; MIC90, 0.5 microgram/ml). All four experimental quinolones as well as RP 59500 show promise for therapy of infections with penicillin-resistant and -susceptible pneumococci.
authors.affiliation: Department of Pathology (Clinical Microbiology), Hershey Medical Center, Pennsylvania 17033.
authors.forename: S K
authors.initials: SK
authors.lastname: Spangler
authors.forename: M R
authors.initials: MR
authors.lastname: Jacobs
authors.forename: P C
authors.initials: PC
authors.lastname: Appelbaum
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology; D004917:Erythromycin / Q000494:pharmacology; D024841:Fluoroquinolones; D006801:Humans; D008826:Microbial Sensitivity Tests; D009287:Naphthyridines; D015242:Ofloxacin / Q000494:pharmacology; D010403:Penicillin Resistance; D015363:Quinolones / Q000494:pharmacology*; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D014640:Vancomycin / Q000494:pharmacology; D014769:Virginiamycin / Q000494:pharmacology*
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D009287:Naphthyridines; D015363:Quinolones; D014769:Virginiamycin; C062556:Win 57273; C062940:quinupristin-dalfopristin; C068217:PD 131628; C054745:temafloxacin; D002939:Ciprofloxacin; D004917:Erythromycin; D014640:Vancomycin; D015242:Ofloxacin; C061363:sparfloxacin