Multiple-Drug Resistance in d -Tartrate-Positive Salmonella enterica Serovar Paratyphi B Isolates from Poultry Is Mediated by Class 2 Integrons Inserted into the Bacterial Chromosome

Abstract
The presence of integrons in 85 multiresistant German isolates of the predominating Salmonella enterica subsp. enterica serovar Paratyphi B dT+ clone was investigated. All isolates possessed a chromosomally located Tn7-like class 2 integron carrying the same dfrA1-sat1-aadA1 array of gene cassettes. Only four isolates (4.7%) revealed an additional class 1 integron with two strains each containing the aadA1 or dfrA1-aadA1 gene cassettes.