Tetracycline and streptomycin resistance genes, transposons, and plasmids in Salmonella enterica isolates from animals in Italy.
Fifty-eight multidrug-resistant Salmonella enterica strains of 20 serotypes, isolated from animal sources in Italy, were analyzed for tet(A) and strA-strB, conferring tetracycline and streptomycin resistance, respectively. The strA and strB genes were highly prevalent in Salmonella strains of our collection, being detected in 84% of the streptomycin-resistant strains. In many strains, the strA and strB genes were linked to a particular Tn5393-derivative transposon characterized by the presence of the insertion sequence IS1133, previously identified only in the plant pathogen Erwinia amylovora. Sixty-eight percent of the tetracycline-resistant strains were tet(A) positive, indicating that this gene is widely diffused in Salmonella strains circulating in animals in Italy. Most of the tet(A) genes were localized within a deleted Tn1721 transposon variant. Two prevalent repN and repI1 resistance plasmids were identified in Salmonella isolates of our collection.
Laboratory of Bacteriology and Medical Mycology, Istituto Superiore di Sanità, Rome, Italy.
Cristina
C
Pezzella
Antonia
A
Ricci
Elisabetta
E
DiGiannatale
Ida
I
Luzzi
Alessandra
A
Carattoli
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003227:Conjugation, Genetic; D017931:DNA Primers; D004251:DNA Transposable Elements / Q000235:genetics*; D005798:Genes, Bacterial; D032023:Integrons / Q000235:genetics; D007558:Italy; D010957:Plasmids / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012480:Salmonella Infections / Q000382:microbiology; D019779:Salmonella enterica / Q000187:drug effects / Q000235:genetics*; D013307:Streptomycin / Q000494:pharmacology*; D013752:Tetracycline / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D017931:DNA Primers; D004251:DNA Transposable Elements; D013752:Tetracycline; D013307:Streptomycin