Selection of naturally occurring extended-spectrum TEM beta-lactamase variants by fluctuating beta-lactam pressure.
Antimicrob Agents Chemother
; 44(8): 2182-4, 2000 Aug.
Article
em En
| MEDLINE
| ID: mdl-10898697
ABSTRACT
Despite the large number of in vitro mutations that increase resistance to extended-spectrum cephalosporins in TEM-type beta-lactamases, only a small number occur in naturally occurring enzymes. In nature, and particularly in the hospital, bacteria that contain beta-lactamases encounter simultaneous or consecutive selective pressure with different beta-lactam molecules. All variants obtained by submitting an Escherichia coli strain that contains a bla(TEM-1) gene to fluctuating challenge with both ceftazidime and amoxicillin contained only mutations previously detected in naturally occurring beta-lactamases. Nevertheless, some variants obtained by ceftazidime challenge alone contained mutations never detected in naturally occurring TEM beta-lactamases, suggesting that extended-spectrum TEM variants in hospital isolates result from fluctuating selective pressure with several beta-lactams rather than selection with a single antibiotic.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Beta-Lactamases
/
Resistência beta-Lactâmica
/
Escherichia coli
/
Antibacterianos
Idioma:
En
Revista:
Antimicrob Agents Chemother
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Espanha