Nusieve agarose gels

Primers (Table 1) were used to amplify and detect the most common resistance genes in Salmonella for the following antibiotics: ampicillin (bla_CMY, bla_OXA, bla_PSE, bla_TEM, and bla_SHV), chloramphenicol (cat, cml, and floR), and streptomycin (aadA2, strA, and strB). Tetracycline resistance genes in these isolates (tetA, B, C, D, and G) were characterized previously (Brunelle et al., 2013 (link)). DNA was obtained by boiling a single colony from each isolate in 30 μl water. Each 25 μL PCR reaction contained 1.5 μl DNA, 1.5 units of Taq polymerase (Promega), 1x PCR buffer with 1.5 mM MgCl₂, 1 mM each dNTP, and 0.8 μM of each primer. Amplification conditions were: 94°C for 1 min; 35 cycles of 94°C for 30 s, 56°C for 30 s, 72°C for 30 s; 72°C for 2 min; 4°C hold. Amplifications were done in duplicate and products were visualized on 2% NuSieve agarose gels (Cambrex, Rockland, ME).