artículo científico
Characterization of an R-Plasmid Associated with Ampicillin Resistance in Shigella dysenteriae Type 1 Isolated from Epidemics
Fecha
1977-03Registro en:
0066-4804
PMC352168
PMC352019
324394
Autor
Crosa, Jorge H.
Olarte Álvarez, Jorge
Mata Jiménez, Leonardo
Luttropp, Linda K.
Peñaranda, María Elena
Institución
Resumen
Ampicillin-resistant strains of Shigella dysenteriae type 1 isolated in epidemics
in Mexico, Central America, and Bangla Desh were examined for the
presence of plasmid deoxyribonucleic acid (DNA) by gel electrophoresis. All
strains contained a heterogeneous population of plasmids. Transfer experiments
to Escherichia coli K-12 indicated that the ampicillin resistance determinant
(Apr) was located on a 5.5-megadalton (Mdal) plasmid identical in all Shiga
strains examined, as judged by DNA hybridization and by its molecular properties.
This 5.5-Mdal plasmid contained the ampicillin transposon (TnA) sequences.
There was not a high degree of homology between the Shiga Apr
plasmid DNA and DNA obtained from Apr Salmonella typhi strains isolated
from typhoid epidemics in Mexico, previous to the dysentery outbreaks. Although
low, the degree of reassociation observed indicated that probably part of
the TnA sequence was present in S. typhi DNA. The DNA hybridization
experiments showed, in addition, that there was a high degree of homology
among Apr plasmids isolated from different enterobacteria, and this identity was
confirmed by restriction endonuclease activity. These results together with their
similarities in molecular and replicative properties indicate that the Apr plasmids,
as was suggested for the Smr Sur plasmids, possibly evolved once and then
epidemiologically spread in the Enterobacteriaceae.