Using the real-time PCR method, we found that the most frequently expressed genes among the strains after the in vitro infection model of the human epithelial cell lines A549 and A431 were the genes encoding adhesins (ycfm, mrkD, and fimH), the genes encoding iron-acquisition systems (irp2, fyuA, entB, and irp-1) and protectins (rpmA; Table 2). This evidence concerns the gene IREB2 and infection.