**2.6 PCR amplification of class 1 and 2 integrons**

The bacterial DNA template preparation and the PCR conditions for the detection of class 1 and class 2 integrons were undertaken as previously described (Miko et al, 2005). The screening for the presence of class 1 and class 2 integrons was carried out using PCR with primers specific for the *intI1* ( and *intI2* (Goldstein et al, 2001)). The primer sequences used are shown in Table 2. Amplifications were performed in 10 μL of 5x Taq PCR Master Mix (Qiagen, Valencia, CA, USA), 2 pmol/L each primer, and 2 μg template DNA. Amplification specifications were as follows: 5 min at 94°C followed by 35 cycles of 1 min at 94°C, 1 min at 55°C, and 30 s at 72°C. PCR products were analyzed by gel electrophoresis with 2 % agarose gels. All PCRs included DNA ladder, positive and negative controls.


Table 2. PCR primers and conditions used in Screening *Salmonella* isolates for presence of class 1 and class 2 integrons; *a* F, Forward; R, Reverse**.** 
