title: The development of chromosomally coded beta-lactamase production by Escherichia coli after in vitro selection with ampicillin, cefoxitin and ceftriaxone.
abstract: Subclones of Escherichia coli K12 921 which produced a chromosomal beta-lactamase were naturally selected in vitro with ampicillin, cefoxitin and ceftriaxone. The selected subclones were identical with respect to beta-lactamase production, resistance spectrum and resistance level, regardless of the selection agent. A ceftriaxone selection following an ampicillin selection led to higher ceftriaxone resistance. The beta-lactamase which was formed hydrolysed ceftriaxone to a measurable extent. After incubation of ceftriaxone with the beta-lactamase, the hydrolysed degradation product was demonstrated by thin-layer chromatography.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D002440:Cefoxitin / Q000494:pharmacology*; D002443:Ceftriaxone / Q000494:pharmacology*; D002855:Chromatography, Thin Layer; D002876:Chromosomes, Bacterial / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D006868:Hydrolysis; D010403:Penicillin Resistance; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D002440:Cefoxitin; D002443:Ceftriaxone; D000667:Ampicillin; D001618:beta-Lactamases