title: Plasmid typing and genetic context of AmpC β-lactamases in Enterobacteriaceae lacking inducible chromosomal ampC genes: findings from a Spanish hospital 1999-2007.
abstract: OBJECTIVE
  To gain insights into ampC transmission between bacterial strains.
  
  
  METHODS
  We examined the genetic context of 117 acquired ampC genes from 27119 Enterobacteriaceae collected between 1999 and 2007. Plasmid analysis was carried out by PCR-based replicon or relaxase typing, S1-PFGE and Southern hybridization. I-CeuI/PFGE was used for isolates not characterized by plasmid analysis. PCR reactions were used to map the genetic organization of the ampC genes.
  
  
  RESULTS
  Among the isolates studied, 81.2% of ampC genes were located on plasmids of known Inc/MOB groups, 7.7% were chromosomally located and 11.1% were not determined. A/C, I1 and K were the most commonly found replicons in plasmids carrying bla(CMY-2), while L/M replicons were associated with bla(DHA-1). bla(ACC-1) was linked to I1 and MOB(F11) plasmids; bla(CMY-27) was associated with IncF and MOB(P12) plasmids; the plasmid carrying bla(CMY-25) could not be typed, and bla(CMY-40) was chromosomally located. All 87 isolates carrying bla(CMY-2), bla(CMY-4), bla(CMY-25), bla(CMY-27), bla(CMY-40) or bla(ACC-1) displayed the transposon-like structures ISEcp1/ΔISEcp1-bla(CMY)-blc-sugE or ΔISEcp1-bla(ACC-1)-gdha. The most prevalent structure in bla(DHA-1) (93.3% of cases) was identical to that described in the Klebsiella pneumoniae pTN60013 plasmid. Remarkably, in three isolates containing chromosomal bla(CMY-2), this gene was mobilized by conjugation.
  
  
  CONCLUSIONS
  Although plasmids are the main cause of the rapid dissemination of ampC genes among bacteria, we need to be aware that other mobile genetic elements such as integrative and conjugative elements (ICEs) can be involved in the mobilization of these genes.
authors: Servei de Microbiologia, Hospital de Santa Creu i Sant Pau, Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Institut d'Investigacions Biomèdiques Sant Pau, Barcelona, Spain.
authors: Caterina
authors: C
authors: Mata
authors: Elisenda
authors: E
authors: Miró
authors: Andrés
authors: A
authors: Alvarado
authors: M Pilar
authors: MP
authors: Garcillán-Barcia
authors: Mark
authors: M
authors: Toleman
authors: Timothy R
authors: TR
authors: Walsh
authors: Fernando
authors: F
authors: de la Cruz
authors: Ferran
authors: F
authors: Navarro
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D015139:Blotting, Southern; D016000:Cluster Analysis; D016521:Electrophoresis, Gel, Pulsed-Field; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000382:microbiology*; D022761:Gene Transfer, Horizontal; D005838:Genotype; D006761:Hospitals; D020071:Interspersed Repetitive Sequences; D058889:Molecular Typing; D010957:Plasmids / Q000032:analysis*; D016133:Polymerase Chain Reaction; D013030:Spain; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; C048795:AmpC beta-lactamases; D001618:beta-Lactamases