dfrA25, a novel trimethoprim resistance gene from Salmonella Agona isolated from a human urine sample in Brazil.
OBJECTIVE
To describe a novel trimethoprim resistance gene, designated dfrA25, which was detected as a gene cassette within a class 1 integron in Salmonella Agona.


METHODS
The gene was cloned into Escherichia coli MT102 and resistance to 10 different antimicrobial drugs was measured. A phylogenetic tree was constructed based on representative trimethoprim-resistance-mediating DfrA proteins retrieved from GenBank. Filter-mating experiments and Southern blots of plasmid preparations were performed with the donor and selected transconjugants.


CONCLUSIONS
dfrA25 encodes a dihydrofolate reductase of 157 amino acids with closest identity (85%) to dfrA5 dihydrofolate reductase. dfrA25 was located on a transferable plasmid (approximately 150 kb) that also harboured the tetracycline resistance gene tet(A).
Agersø
Yvonne
Y
WHO Collaborating Centre for Antimicrobial Resistance in Foodborne Pathogens, Danish Institute for Food and Veterinary Research, Bulowsvej 27, DK-1790 Copenhagen V, Denmark. ya@dfvf.dk
Peirano
Gisele
G
Aarestrup
Frank M
FM
D001483:Base Sequence; D001938:Brazil; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D012475:Salmonella / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D012480:Salmonella Infections / Q000382:microbiology* / Q000652:urine; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics*; D014296:Trimethoprim Resistance / Q000235:genetics*; D014556:Urine / Q000382:microbiology
D013762:Tetrahydrofolate Dehydrogenase