Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8737297 | Diagnostic Microbiology and Infectious Disease | 2018 | 24 Pages |
Abstract
We described bacterial killing and resistance emergence at various fixed concentrations of meropenem and piperacillin/tazobactam against Pseudomonas aeruginosa and Escherichia coli. Time-kill studies were conducted utilizing nine isolates and a large range of concentrations. Within each strain and antibiotic, initial killing was similar, with concentrations â¥2ÃMIC. At many (strain-specific) concentrations causing substantial initial killing, regrowth occurred at 24-48h. For remaining concentrations, growth typically remained suppressed (<5-log10 cfu/mL). The concentrations of meropenem required to suppress regrowth ranged from 2-8ÃMIC for P. aeruginosa and 2-64ÃMIC for E. coli. For piperacillin/tazobactam, the equivalent concentrations ranged from 8-16ÃMIC for P. aeruginosa and 4-16ÃMIC for E. coli. The number of less-susceptible bacteria increased with rising concentrations before decreasing at even higher concentrations. Suppression of regrowth and resistance was substantially improved with higher concentrations (typically â¥8ÃMIC), suggesting a benefit of higher β-lactam concentrations beyond those required for maximum initial killing.
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Authors
Phillip J. Bergen, Jürgen B. Bulitta, Fekade B. Sime, Jeffrey Lipman, Megan J. McGregor, Nada Millen, David L. Paterson, Carl M.J. Kirkpatrick, Jason A. Roberts, Cornelia B. Landersdorfer,