In vitro activity of piperacillin/tazobactam and ertapenem against Bacteroides fragilis and Escherichia coli in pure and mixed cultures.
Ertapenem and piperacillin/tazobactam are beta-lactam antibiotics with a broad spectrum of activity used for the treatment of mixed infections in which Bacteroides fragilis and Escherichia coli play an important aetiological role. In this study, the activities of piperacillin/tazobactam and ertapenem (MIC and time-kill kinetics) against these bacteria were compared. MICs were determined by the agar dilution method, and the time and slope of time-kill curves were analysed. In the in vitro pharmacodynamic assays, pure and mixed cultures of E. coli and B. fragilis were exposed to peak concentrations of ertapenem (8.0 microg ml(-1)) and piperacillin/tazobactam (64.0/8.0 microg ml(-1)) for 48 h. Treatment with ertapenem reduced the viability of E. coli and/or B. fragilis by 3 logs in all experiments, whereas piperacillin/tazobactam only affected the viability of B. fragilis. Both drugs exhibited their fastest rates of killing when bacteria were grown in mixed cultures. According to the results, ertapenem exhibited activity similar to that of piperacillin/tazobactam against B. fragilis alone or in mixed culture. However, ertapenem exhibited a markedly higher activity against E. coli alone or in combination with B. fragilis relative to piperacillin/tazobactam.
Valéria Dos Santos
Kênia
K
Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Diniz
Cláudio Galuppo
CG
Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Coutinho
Simone Cristina
SC
Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Apolônio
Ana Carolina Morais
ACM
Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Geralda de Sousa-Gaia
Luciana
L
Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Nicoli
Jacques Robert
JR
Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Farias
Luiz de Macêdo
LM
Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Roque de Carvalho
Maria Auxiliadora
MA
Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001441:Bacteroides fragilis / Q000187:drug effects*; D015169:Colony Count, Microbial; D000077727:Ertapenem; D004926:Escherichia coli / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability; D010397:Penicillanic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D010878:Piperacillin / Q000494:pharmacology; D000077725:Piperacillin, Tazobactam Drug Combination; D013997:Time Factors; D047090:beta-Lactams / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D000077725:Piperacillin, Tazobactam Drug Combination; D010397:Penicillanic Acid; D000077727:Ertapenem; D010878:Piperacillin