The effect of Tn916 insertions on contour-clamped homogeneous electrophoresis patterns of Enterococcus faecalis.
AUTOR(ES)
Thal, L A
RESUMO
Contour-clamped homogeneous gel electrophoresis has increasingly been used and has generally been considered the method of choice for the delineation of enterococcial strains. It has been suggested that the contour-clamped homogeneous electric field (CHEF) electrophoresis digestion patterns of genomic DNA indicate the relatedness of strains when SmaI patterns differ by six or fewer bands. To evaluate the potential reasons for the diversity of bands among clonally related isolates, we studied plasmid-free Enterococcus faecalis FA2-2 and derivatives with transposon Tn916 (encoding for tetracycline resistance) insertions on the chromosome. We obtained derivatives with seven different Tn916 insertion sites and up to two copies of Tn916 on the chromosome, resulting in differences of one to seven bands by CHEF electrophoresis; eight different patterns were observed. With Tn916 insertions, there was either (i) loss of a band(s) with the generation of a new band(s), (ii) the generation of a new band(s) only, or (iii) the loss of a band(s) with no new visible band(s). These results indicate that strains can have up to seven different SmaI bands by CHEF electrophoresis and still be closely related.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=229712Documentos Relacionados
- Comparison of field inversion gel electrophoresis with contour-clamped homogeneous electric field electrophoresis as a typing method for Enterococcus faecium.
- DNA hybridization and contour-clamped homogeneous electric field electrophoresis for identification of enterococci to the species level.
- Resolution of DNA molecules greater than 5 megabases by contour-clamped homogeneous electric fields.
- Evidence that coupling sequences play a frequency-determining role in conjugative transposition of Tn916 in Enterococcus faecalis.
- Hyperhemolytic phenomena associated with insertions of Tn916 into the hemolysin determinant of Enterococcus faecalis plasmid pAD1.