Presence of tetracycline resistant bacteria and genes in grasslandbased animal production systems
Autor
López, Liliana
Santamaría, Johanna
Sánchez, Alexandra
Castro, Lida
Moreno, Jessica L.
Institución
Resumen
This study assessed the presence of tetracycline-resistant
bacteria in five different grassland-based production systems dedicated to raising dairy cattle
located in the Colombian Andes. Animal (ruminal fluid and feces) and environmental (soil and
water) samples were evaluated, and resistant heterotrophic bacteria were found in rumen fluid,
feces, soil, and runoff water samples. The resistant bacteria were isolated and identified based
on the 16S rDNA region. Subsequently, they were evaluated for the presence of tet genes,
which encode ribosomal protection proteins and membrane efflux pumps. The most frequent
phyla detected were Firmicutes and Proteobacteria. The most common resistance genes found
were tet(W), tet(Q), and tet(M). The nucleotide sequences of the genes showed no differences
in bacteria isolated from environmental samples versus ruminal fluid and feces. This result
suggests that the observed environmental resistance in the evaluated grasslands is the result of
horizontal gene transfer from animals to the environment