title: Tandem multiplication of the IS26-flanked amplicon with the bla(SHV-5) gene within plasmid p1658/97.
abstract: The IncF plasmid p1658/97 (c. 125 kb) from Escherichia coli isolates recovered during a clonal outbreak in a hospital in Warsaw, Poland, in 1997 contains the extended-spectrum β-lactamase (ESBL) gene bla(SHV-5), originated from the Klebsiella pneumoniae chromosome. A region containing the bla(SHV-5) gene is flanked by two IS26 copies and its copy number multiplies spontaneously within p1658/97 and RecA-deficient E. coli strains. Here, we demonstrate that the amplified IS26-bla(SHV-5) units were arranged in tandems, containing up to more than 10 units, which could raise ceftazidime MICs for host strains from 4 μg mL(-1) to more than 128 μg mL(-1). Successive deletions within p1658/97, located outside the amplifiable module and encompassing even as little as c. 15% of the plasmid, blocked the amplification. Moreover, the complementing re-introduction of the deleted fragments in trans did not restore the process. Similarly, insertions of a 1-kb DNA fragment into the amplicon inhibited its self-multiplication ability. The module was able to transmit into another IS26-containing plasmid by recombination. The results prompted us to speculate that local DNA structure, especially favorable in p1658/97, might have been responsible for the IS26-bla(SHV-5) multiplication ability.
authors: Department of Microbial Biochemistry, Institute of Biochemistry and Biophysics of Polish Academy of Sciences, Warsaw, Poland. maximus@biol.uw.edu.pl
authors: Maksymilian
authors: M
authors: Zienkiewicz
authors: Izabela
authors: I
authors: Kern-Zdanowicz
authors: Alessandra
authors: A
authors: Carattoli
authors: Marek
authors: M
authors: Gniadkowski
authors: Piotr
authors: P
authors: Cegłowski
mesh_terms: D002442:Ceftazidime / Q000494:pharmacology; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D004196:Disease Outbreaks; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D018628:Gene Dosage; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D007711:Klebsiella pneumoniae / Q000235:genetics; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics / Q000378:metabolism*; D011044:Poland / Q000453:epidemiology; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D017384:Sequence Deletion; D020080:Tandem Repeat Sequences; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D002442:Ceftazidime; D011938:Rec A Recombinases; C117193:beta-lactamase SHV-5; D001618:beta-Lactamases