title: Two novel CMY-2-type β-lactamases encountered in clinical Escherichia coli isolates.
abstract: BACKGROUND
  Chromosomally encoded AmpC β-lactamases may be acquired by transmissible plasmids which consequently can disseminate into bacteria lacking or poorly expressing a chromosomal bla AmpC gene. Nowadays, these plasmid-mediated AmpC β-lactamases are found in different bacterial species, namely Enterobacteriaceae, which typically do not express these types of β-lactamase such as Klebsiella spp. or Escherichia coli. This study was performed to characterize two E. coli isolates collected in two different Portuguese hospitals, both carrying a novel CMY-2-type β-lactamase-encoding gene.
  
  
  RESULTS
  Both isolates, INSRA1169 and INSRA3413, and their respective transformants, were non-susceptible to amoxicillin, amoxicillin plus clavulanic acid, cephalothin, cefoxitin, ceftazidime and cefotaxime, but susceptible to cefepime and imipenem, and presented evidence of synergy between cloxacilin and cefoxitin and/or ceftazidime. The genetic characterization of both isolates revealed the presence of bla CMY-46 and bla CMY-50 genes, respectively, and the following three resistance-encoding regions: a Citrobacter freundii chromosome-type structure encompassing a blc-sugE-bla CMY-2-type -ampR platform; a sul1-type class 1 integron with two antibiotic resistance gene cassettes (dfrA1 and aadA1); and a truncated mercury resistance operon.
  
  
  CONCLUSIONS
  This study describes two new bla CMY-2-type genes in E. coli isolates, located within a C. freundii-derived fragment, which may suggest their mobilization through mobile genetic elements. The presence of the three different resistance regions in these isolates, with diverse genetic determinants of resistance and mobile elements, may further contribute to the emergence and spread of these genes, both at a chromosomal or/and plasmid level.
authors.affiliation: Department of Infectious Diseases, National Reference Laboratory of Antibiotic Resistances and Healthcare Associated Infections, National Institute of Health Dr. Ricardo Jorge, Av. Padre Cruz, 1649-016, Lisbon, Portugal. vera.manageiro@insa.min-saude.pt.|Centre for the Study of Animal Sciences (ICETA), University of Oporto, Oporto, Portugal. vera.manageiro@insa.min-saude.pt.
authors.forename: Vera
authors.initials: V
authors.lastname: Manageiro
authors.affiliation: Department of Infectious Diseases, National Reference Laboratory of Antibiotic Resistances and Healthcare Associated Infections, National Institute of Health Dr. Ricardo Jorge, Av. Padre Cruz, 1649-016, Lisbon, Portugal. eugenia.ferreira@insa.min-saude.pt.
authors.forename: Eugénia
authors.initials: E
authors.lastname: Ferreira
authors.affiliation: Laboratory of Microbiology, Hospital Garcia de Orta, EPE, Almada, Portugal. margaridafeijopinto@gmail.com.|Present address: Laboratory of Microbiology, Centro Hospitalar de Lisboa Central, EPE, Lisbon, Portugal. margaridafeijopinto@gmail.com.
authors.forename: Margarida
authors.initials: M
authors.lastname: Pinto
authors.affiliation: Laboratory of Clinical Pathology, Hospital de Santa Luzia, Viana do Castelo, Portugal. ffonseca@chpvvc.min-saude.pt.|Present address: Laboratory of Clinical Pathology, Centro Hospitalar de Póvoa de Varzim-Vila do Conde, EPE, Póvoa de Varzim, Portugal. ffonseca@chpvvc.min-saude.pt.
authors.forename: Fernando
authors.initials: F
authors.lastname: Fonseca
authors.affiliation: Department of Infectious Diseases, National Reference Laboratory of Antibiotic Resistances and Healthcare Associated Infections, National Institute of Health Dr. Ricardo Jorge, Av. Padre Cruz, 1649-016, Lisbon, Portugal. ura.cbac@insa.min-saude.pt.
authors.forename: Mónica
authors.initials: M
authors.lastname: Ferreira
authors.affiliation: CHU Clermont-Ferrand, Laboratoire de Bactériologie, Clermont-Ferrand, France. rbonnet@chu-clermontferrand.fr.
authors.forename: Richard
authors.initials: R
authors.lastname: Bonnet
authors.affiliation: Department of Infectious Diseases, National Reference Laboratory of Antibiotic Resistances and Healthcare Associated Infections, National Institute of Health Dr. Ricardo Jorge, Av. Padre Cruz, 1649-016, Lisbon, Portugal. manuela.canica@insa.min-saude.pt.
authors.forename: Manuela
authors.initials: M
authors.lastname: Caniça
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000382:microbiology*; D006801:Humans; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; C103022:beta-lactamase CMY-2; D001618:beta-Lactamases