FIG. 1.
(A) Amplified gene cassettes and corresponding IP groups of representative strains of S. enterica serotype Typhimurium. After PCR, 10 μl of the amplified reaction mixture was loaded onto a 1% agarose gel in 1× Tris-EDTA-acetate (TAE) buffer containing 0.1 μg of ethidium bromide per ml. Samples were horizontally electrophoresed at 100 V for 90 min. The lanes marked M contain grade III molecular weight markers ranging in size from 0.56 to 21.2 kb and grade V molecular weight markers ranging in size from 8 to 597 bp (Roche Diagnostics). The asterisks represent the gene cassettes selected for sequencing. Lanes (IP type): 1, CIT-F45 (I); 2, CIT-F41 (II); 3, CIT-F44 (III); 4, CIT-V75 (IV); 5, CIT-V111 (V); 6, CIT-H11 (VI); 7, CIT-H183 (VII); 8, CIT-F46 (none detected); 9, E. coli R100.1 (control); 10, E. coli R751 (control). (B) Following PFGE, the XbaI macrorestricted DNA fragments were transferred to nylon membranes. Individual gene cassettes were then used to probe the membranes. The Southern blot using the blaPSE-1 gene as a probe is shown. The lanes marked M contain DIG-labeled DNA molecular weight marker grade II (Roche Diagnostics). The unlabeled mid-range PFG Markers (New England BioLabs) in lane M* were included for fragment sizing before Southern transfer. Lanes (IP type): 1, CIT-V38 (I); 2, CIT-F45 (I); 3, CIT-H164 (I); 4, CIT-H176 (I); 5, CIT-H183 (VII); 6, CIT-V115 (I); 7, CIT-F107 (I); 8, CIT-H144 (I); 9, CIT-V37 (I); 10, CIT-F34 (IV); 11, CIT-F41 (II); 12, CIT-F44 (III); 13, CIT-V60 (IV); 14, CIT-V75 (IV); 15, CIT-V127 (II); 16, CIT-V129 (IV); 17, CIT-F40 (V); 18, CIT-F105 (V); 19, CIT-H195 (IV); 20, E. coli R100.1; 21, E. coli R751.