title: Characterization of beta-lactamases encoded by pathogenic strains of Escherichia coli from Portugal.
abstract: A survey of 2036 strains of Escherichia coli was conducted in Oporto, Portugal, to establish the prevalence of resistance to beta-lactam antibiotics. Isolates were from hospital and clinical practice patients, and were further divided into urinary and non-urinary pathogens. A high level of resistance to aminopenicillins (55.3%) was observed. Further examination of the resistant strains showed that the frequencies of occurrence of known beta-lactamases were as follows: TEM-1 (78.2% of resistant strains); SHV-1 (7.9%); TEM-2 (0.45%); OXA-1 (1.5%); HMS-1 (0.18%); TEM-1 + SHV-1 (4.2%). Other pairs of beta-lactamases were also identified in less than 2% of the resistant strains. In addition, 4.7% of the resistant strains produced elevated levels of a presumed chromosomal cephalosporinase, while 0.9% produced a ceftazimidase of pI 5.8-5.9 which was similar to TEM-6.
authors.affiliation: Faculdade de Farmácia da Universidade do Porto, Oporto, Portugal.
authors.forename: J C
authors.initials: JC
authors.lastname: Sousa
authors.forename: G
authors.initials: G
authors.lastname: Carneiro
authors.forename: M L
authors.initials: ML
authors.lastname: Peixe
authors.forename: M L
authors.initials: ML
authors.lastname: Queirós
authors.forename: I
authors.initials: I
authors.lastname: Rebelo
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D004927:Escherichia coli Infections / Q000382:microbiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D011174:Portugal; D001618:beta-Lactamases / Q000032:analysis* / Q000235:genetics; D047090:beta-Lactams
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D001618:beta-Lactamases