title: Complex class 1 integrons harboring CTX-M-2-encoding genes in clinical Enterobacteriaceae from a hospital in Brazil.
abstract: BACKGROUND
  CTX-M enzymes are the most prevalent extended-spectrum beta-lactamases (ESBLs) in Brazil and around the world. The spread of CTX-M lies in their ability to be mobilized by insertion sequences and integrons. This study aimed to identify the mobile genetic structures associated with bla(CTX-M) genes from clinical Enterobacteriaceae strains.
  
  
  METHODS
  Twenty-eight clinical non-clonal Enterobacteriaceae were screened by PCR for the presence of bla(CTX-M) genes and class 1 integrase (int1), and for the association of bla(CTX-M) with class 1 integrons. Plasmid incompatibility groups were assessed by PBRT. Wild-type plasmids were transformed into electrocompetent E. coli, and the S1-PFGE technique was used to verify the presence of high-molecular-weight plasmids in both wild-type strains and E. coli transformants.
  
  
  RESULTS
  Sequencing showed that strains carried bla(CTX-M-2) (n = 25) and bla(CTX-M-59) (n = 3) genes inserted into the 3'-end of complex class 1 integrons. Thirteen strains also carried bla(TEM) and bla(SHV) genes. CTX-M-2/59-containing complex class 1 integrons were also present in E. coli transformants. The most frequent Inc groups were IncA/C (n = 10) and IncF (n = 8). Heavy plasmids were observed in both wild-type strains and E. coli transformants.
  
  
  CONCLUSIONS
  The presence of the same bla(CTX-M-2-group)-containing genetic structure in seven Enterobacteriaceae species isolated at seven hospital wards shows the great mobility potential of complex class 1 integrons. Also, this is the first report of TEM-15, SHV-45, and SHV-55 in Latin America. The genetic environment of bla(CTX-M-2) accounts for their maintenance and spread among Gram-negative bacteria.
authors: School of Public Health, University of São Paulo, São Paulo, Brazil. milenadropa@gmail.com.
authors: Milena
authors: M
authors: Dropa
authors: Livia Carminato
authors: LC
authors: Balsalobre
authors: Nilton
authors: N
authors: Lincopan
authors: Glavur Rogério
authors: GR
authors: Matté
authors: Maria Helena
authors: MH
authors: Matté
mesh_terms: D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics*; D001938:Brazil / Q000453:epidemiology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D017931:DNA Primers; D004269:DNA, Bacterial / Q000032:analysis; D024881:Drug Resistance, Bacterial; D004755:Enterobacteriaceae / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D016133:Polymerase Chain Reaction; D001618:beta-Lactamases / Q000145:classification / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; C071167:beta-lactamase CTX-2; D001618:beta-Lactamases