title: Analysis of beta-lactamase production in ampicillin-resistant Escherichia coli isolated from blood cultures 1983-1989.
abstract: From 1983 to 1989, 520 Escherichia coli blood culture pathogens were isolated from two hospitals in Turku, Finland. Ampicillin resistance (MIC greater than or equal to 16 micrograms/ml) of these isolates increased from 33% in 1983 to 66% in 1987, but decreased to 38-49% in 1988-1989. Occurrence of TEM-1 beta-lactamase producing isolates increased only slightly from 14% in 1983 to 25% in 1989 among all Escherichia coli strains studied. Strains with ampicillin MIC values of 16 micrograms/ml and 32 micrograms/ml were mostly responsible for the increase in resistance. Among these isolates, TEM-1 or any other of the well known plasmid-mediated beta-lactamases were not found by hybridization or isoelectric focusing.
authors.affiliation: Department of Medical Microbiology, Turku University, Finland.
authors.forename: T
authors.initials: T
authors.lastname: Arstila
authors.forename: S
authors.initials: S
authors.lastname: Huovinen
authors.forename: P
authors.initials: P
authors.lastname: Huovinen
mesh_terms: D000668:Ampicillin Resistance / Q000235:genetics*; D016470:Bacteremia / Q000382:microbiology; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology; D006801:Humans; D007525:Isoelectric Focusing; D008826:Microbial Sensitivity Tests; D009693:Nucleic Acid Hybridization; D010957:Plasmids / Q000235:genetics; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D001618:beta-Lactamases; C034413:beta-lactamase TEM-1