L-658,310, a new injectable cephalosporin. II. In vitro and in vivo interactions between L-658,310 and various aminoglycosides or ciprofloxacin versus clinical isolates of Pseudomonas aeruginosa.
Combinations of L-658,310 and an aminoglycoside or ciprofloxacin were tested against clinical isolates of Pseudomonas aeruginosa using a checkerboard broth dilution technique. Using the mean fractional bactericidal concentration of less than or equal to 0.5 as the criterion for synergy, the combinations L-658,310/tobramycin and L-658,310/ciprofloxacin against strains of P. aeruginosa resistant to the companion drug were synergistic. The data plotted as isobolograms showed synergy for all combinations tested. Synergy was clearly demonstrated in time-kill experiments. A greater than 3-log decrease in viable cell count for P. aeruginosa was seen after exposure for 24 hours to subinhibitory concentrations of the combined agents. In in vivo mouse models, the efficacy of L-658,310 against experimental P. aeruginosa bacteremias was enhanced by the addition of a low dose of an aminoglycoside to the treatment regimen, thus confirming the synergy demonstrated in time-kill experiments.
Valiant
M E
ME
Merck Sharp & Dohme Research Laboratories, Rahway, New Jersey 07065-0900.
Gilfillan
E C
EC
Gadebusch
H H
HH
Pelak
B A
BA
D000583:Amikacin / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D002511:Cephalosporins / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D004357:Drug Synergism; D005260:Female; D005839:Gentamicins / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D054833:Isoindoles; D051379:Mice; D011552:Pseudomonas Infections / Q000188:drug therapy; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D014031:Tobramycin / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D005839:Gentamicins; D054833:Isoindoles; C053266:BO 1236; D002939:Ciprofloxacin; D000583:Amikacin; D014031:Tobramycin