Comparison of the risk of acquiring in vitro resistance to doripenem and tazobactam/piperacillin by CTX-M-15-producing Escherichia coli.
J Infect Chemother
; 21(5): 381-4, 2015 May.
Article
em En
| MEDLINE
| ID: mdl-25662788
ABSTRACT
To compare the risk of acquiring in vitro resistance between doripenem and tazobactam/piperacillin by CTX-M-15-producing Escherichia coli, the in vitro frequency of resistance was determined. Four strains carrying multiple ß-lactamases such as blaOXA-1 or blaCTX-M-27 as well as blaCTX-M-15 and blaTEM-1 were used. No resistant colonies appeared on doripenem-containing plates, whereas resistant colonies were obtained from three of four test strains against tazobactam/piperacillin using agar plate containing 8- to 16-fold MIC of each drug. These three acquired tazobactam/piperacillin-resistant strains were not cross-resistant to doripenem, and they showed 1.9- to 3.1-fold higher piperacillin-hydrolysis activity compared to those of each parent strain. The change of each ß-lactamase mRNA expression measured by real-time PCR varied among three resistant strains. One of three tazobactam/piperacillin-resistant strains with less susceptibility to ceftazidime overexpressed both blaCTX-M-15 and blaTEM-1, and the other two strains showed higher mRNA expression of either blaTEM-1 or blaOXA-1. These results demonstrate that multiple ß-lactamases carried by CTX-M-15-producing E. coli contributed to the resistance to tazobactam/piperacillin. On the other hand, these resistant strains maintained susceptibility to doripenem. The risk of acquiring in vitro resistance to doripenem by CTX-M-15-producing E. coli seems to be lower than that to tazobactam/piperacillin.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Beta-Lactamases
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Carbapenêmicos
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Ácido Penicilânico
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Farmacorresistência Bacteriana Múltipla
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Escherichia coli
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Antibacterianos
Tipo de estudo:
Etiology_studies
/
Risk_factors_studies
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article