Comparative activities of piperacillin and tazobactam against clinical isolates of Legionella spp.
We evaluated the in vitro activity of piperacillin alone or in combination with the beta-lactamase inhibitor tazobactam against clinical isolates of Legionella species. At an inoculum of approximately 10(4) CFU, tazobactam, piperacillin, and the 8:1 combination had equivalent activities against Legionella spp. At an approximately 10-fold higher inoculum, the following results were obtained, expressed as MICs for 50 and 90% of strains tested (MIC range): piperacillin, 4 and 16 (0.25 to 32) micrograms/ml; tazobactam, 0.5 and 1 (0.125 to 2) micrograms/ml; and piperacillin-tazobactam (expressed in terms of MIC of piperacillin) 0.5 and 1 (0.03 to 2) micrograms/ml. Tazobactam alone and the combination with piperacillin were more active than piperacillin alone at the higher inoculum.
Collins
L A
LA
Department of Medicine, Deaconess Hospital, Boston, Massachusetts 02215.
Wennersten
C B
CB
Ferraro
M J
MJ
Moellering
R C
RC
Eliopoulos
G M
GM
D004357:Drug Synergism; D004359:Drug Therapy, Combination / Q000494:pharmacology*; D006801:Humans; D007875:Legionella / Q000187:drug effects*; D007876:Legionellosis / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D010397:Penicillanic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D010878:Piperacillin / Q000494:pharmacology; D000078142:Tazobactam; D065093:beta-Lactamase Inhibitors
D065093:beta-Lactamase Inhibitors; D010397:Penicillanic Acid; D000078142:Tazobactam; D010878:Piperacillin