title: Outer-membrane proteins pattern and detection of beta-lactamases in clinical isolates of imipenem-resistant Acinetobacter baumannii from Brazil.
abstract: In order to compare imipenem-sensitive and -resistant Acinetobacter baumannii strains isolated from three patients, ribotyping, plasmid, beta-lactamase detection and outer-membrane analysis were performed. Ribotyping and the use of a beta-lactam during the period when the strains were isolated suggested that they had a common origin and that resistance occurred in vivo. Outer membrane analysis showed no difference between susceptible and resistant strains with the exception of an A2 imipenem-resistant strain that lost a protein band of 31-36 kDa. Beta-lactamases were detected using isoelectric focusing in all strains (pI of 7.4). In addition, two beta-lactamases (pI of 5.9 and 6.7) were found in imipenem-resistant isolates. The double-disc technique demonstrated the presence of a beta-lactamase capable of imipenem inactivation in resistant strains. Plasmid analysis showed that all susceptible strains had the same pattern, one resistant strain did not have any plasmid, one had the same plasmid pattern of its susceptible pair and only one had a different pattern when compared with its susceptible pair.
authors.affiliation: Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil. josem.vieira@prodigy.net
authors.forename: S F
authors.initials: SF
authors.lastname: Costa
authors.forename: J
authors.initials: J
authors.lastname: Woodcock
authors.forename: M
authors.initials: M
authors.lastname: Gill
authors.forename: R
authors.initials: R
authors.lastname: Wise
authors.forename: A A
authors.initials: AA
authors.lastname: Barone
authors.forename: H
authors.initials: H
authors.lastname: Caiaffa
authors.forename: A S
authors.initials: AS
authors.lastname: Levin
mesh_terms: D000150:Acinetobacter / Q000737:chemistry / Q000145:classification* / Q000302:isolation & purification; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis*; D015373:Bacterial Typing Techniques; D001938:Brazil; D002876:Chromosomes, Bacterial / Q000235:genetics; D015169:Colony Count, Microbial; D004275:DNA, Ribosomal / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D007525:Isoelectric Focusing; D008297:Male; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000032:analysis; D013845:Thienamycins / Q000494:pharmacology*; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000032:analysis* / Q000737:chemistry
chemical_list: D001425:Bacterial Outer Membrane Proteins; D004275:DNA, Ribosomal; D013845:Thienamycins; D015378:Imipenem; D001618:beta-Lactamases