title: Complex genetic structures with repeated elements, a sul-type class 1 integron, and the blaVEB extended-spectrum beta-lactamase gene.
abstract: Two clinical isolates of Pseudomonas aeruginosa, TL-1 and TL-2, were isolated from a patient transferred from Bangladesh and hospitalized for osteomyelitis in Paris, France. P. aeruginosa TL-1 expressed the extended-spectrum beta-lactamase VEB-1a and was susceptible only to imipenem and colistin, while P. aeruginosa TL-2 expressed only the naturally occurring bla(AmpC) gene at a basal level and exhibited a wild-type beta-lactam resistance phenotype. In TL-1, the typical 5'-end conserved sequence (5'-CS) region of class 1 integrons usually present upstream of the bla(VEB-1a) gene was replaced by a truncated 3'-CS and a 135-bp repeated element (Re). Downstream of the bla(VEB-1a) gene, an insertion sequence, ISPa31 disrupted by ISPa30, and an orf513 sequence, belonging to a common region (conserved region 1 [CR1]) immediately upstream of the aphA-6 gene, were present. Further downstream, a second truncated 3'-CS region in direct repeat belonged to In51, an integron containing two gene cassettes (aadA6 and the OrfD cassette). Thus, the overall structure corresponded to a sul-type class 1 integron termed In121. Genetic analyses revealed that both isolates were clonally related and differed by a ca. 100-kb fragment that contained In121. Both isolates contained another integron, In122, that carried three gene cassettes: aadB, dfrA1, and the OrfX cassette. This work identifies for the first time the spread of Re-associated bla(VEB) genes located on a sul-type integron. It also reports for the first time a CR1 element in P. aeruginosa that is associated with an aminoglycoside resistance aphA-6 gene that is expressed from a composite promoter.
authors.affiliation: Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre Cedex, France. thierry.naas@bct.ap-hop-paris.fr
authors.forename: Thierry
authors.initials: T
authors.lastname: Naas
authors.forename: Daniel
authors.initials: D
authors.lastname: Aubert
authors.forename: Thierry
authors.initials: T
authors.lastname: Lambert
authors.forename: Patrice
authors.initials: P
authors.lastname: Nordmann
mesh_terms: D000483:Alleles; D001483:Base Sequence; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D003001:Cloning, Molecular; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006801:Humans; D032023:Integrons / Q000235:genetics*; D007525:Isoelectric Focusing; D008826:Microbial Sensitivity Tests; D008957:Models, Genetic; D008969:Molecular Sequence Data; D021141:Nucleic Acid Amplification Techniques; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D020079:Terminal Repeat Sequences / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics*; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D004269:DNA, Bacterial; D047090:beta-Lactams; D001618:beta-Lactamases