Activities of imipenem and cephalosporins against clonally related strains of Escherichia coli hyperproducing chromosomal beta-lactamase and showing altered porin profiles.
Forty clonally related clinical isolates of Escherichia coli from hospitalized patients were resistant to cefoxitin (MICs, >256 microg/ml) and ceftazidime (MICs, 32 to 256 microg/ml) and were intermediate or resistant to cefotaxime (MICs, 16 to 128 microg/ml) but susceptible to both cefepime (MICs, 0.5 to 2 microg/ml) and imipenem (MICs, 0.125 to 0.25 microg/ml). Resistance to beta-lactams was related to high-level production of AmpC beta-lactamase and loss of OmpF porin.
Martínez-Martínez
L
L
Department of Microbiology, School of Medicine, Seville, Spain. lmartin@cica.es
Conejo
M C
MC
Pascual
A
A
Hernández-Allés
S
S
Ballesta
S
S
Ramírez De Arellano-Ramos
E
E
Benedí
V J
VJ
Perea
E J
EJ
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology*; D002876:Chromosomes, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D018272:Porins / Q000378:metabolism*; D018440:beta-Lactam Resistance / Q000502:physiology; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D018272:Porins; D015378:Imipenem; D001618:beta-Lactamases