Large Conjugative Plasmids from Clinical Strains of Salmonella enterica Serovar Virchow Contain a Class 2 Integron in Addition to Class 1 Integrons and Several Non-Integron-Associated Drug Resistance Determinants

摘要

Two large conjugative resistance (R) plasmids from clinical strains of Salmonella enterica serovar Virchow carried a class 2 integron with the 5′ conserved sequence (5′CS)-dfrA1-sat1-aadA1-3′CS gene array, which is associated with defective Tn7 transposons. In addition, each contained a different class 1 integron (with 5′CS-aadA1-3′CS or 5′CS-sat-smr-aadA1-3′CS gene arrays) linked to Tn21-Tn9 sequences, and several non-integron-associated R determinants. An intact copy of Tn7 (including the class 2 integron) was present in the chromosome of each strain.