SPI1 and pyelonephritis: A mutual impact of one adhesin on the expression of another adhesin is a so-called “regulatory cross-talk between adhesions.” Such direct communication has been shown between the two adhesin gene clusters T1F and pyelonephritis-associated pili in uropathogenic E. coli (Xia et al., 2000) and for regulation of expression of flagellar, SPI1, and type 1 fimbrial genes in Salmonella (Saini et al., 2010).