FIG. 3.

Expression of smeDEF RNA by clinical isolates of S. maltophilia. The expression of smeDEF was analyzed by RT-PCR. RNAs obtained at the exponential (lanes a) and stationary (lanes b) growth phases were analyzed. A clear band of the predicted size was observed for strains D457R, C357, E729, E923, and F375; and a very faint band was observed for strain D457. Note that strain D457R is not a clinical isolate but a multidrug-resistant mutant derived from strain D457 (3), and it has been included in the present analysis as a control for smeDEF expression. Lane M, molecular size markers (from top to bottom, 404, 331, 242, 190, 157, 147, and 112 bp); C+, positive control, for which PCR was performed with chromosomal DNA from S. maltophilia D457 as the template; C−, negative control, for which PCR was performed without DNA.