title: Cephalosporinase over-expression resulting from insertion of ISAba1 in Acinetobacter baumannii.
abstract: ISAba1-like sequences were identified immediately upstream of the bla(ampC) gene in ceftazidime-resistant Acinetobacter baumannii isolates, but were absent in ceftazidime-susceptible A. baumannii isolates. AmpC over-expression resulted from insertion of ISAba1-like sequences upstream of bla(ampC). ISAba1 provided strong promoter sequences, and it was demonstrated that the change in the ribosome binding site sequence resulting from insertion of ISAba1 did not influence expression of the bla(ampC) gene. Sequence analysis revealed that AmpC sequences of A. baumannii isolates were almost identical and that ISAba1 elements had a high percentage of identity.
authors.affiliation: Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, Université Paris XI, Le Kremlin-Bicêtre, France.
authors.forename: C
authors.initials: C
authors.lastname: Héritier
authors.forename: L
authors.initials: L
authors.lastname: Poirel
authors.forename: P
authors.initials: P
authors.lastname: Nordmann
mesh_terms: D040981:Acinetobacter baumannii / Q000201:enzymology / Q000235:genetics*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D001483:Base Sequence; D002510:Cephalosporinase / Q000096:biosynthesis* / Q000235:genetics; D004251:DNA Transposable Elements / Q000235:genetics*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D015870:Gene Expression; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D011995:Recombination, Genetic; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D018440:beta-Lactam Resistance / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D012333:RNA, Messenger; D002510:Cephalosporinase; C048795:AmpC beta-lactamases; D001618:beta-Lactamases