EFFECT OF SALICYLATE, BISMUTH, OSMOLYTES, AND TETRACYCLINE RESISTANCEON EXPRESSION OF FIMBRIAE BY ESCHERICHIA-COLI

Adherence of Escherichia coil is facilitated by fimbriae and several o uter membrane proteins (OMPs). Hypertonic conditions, salicylate, and Mar mutations are known to reduce OmpF expression. We speculated that OMPs involved in export or assembly of fimbrial subunits might be simi larly affected. To explore this hypothesis, E. coli expressing P, type 1, S, colonization factor antigen I (CFA/I), or CFA/II fimbriae was g rown in the presence of salicylate, bismuth salts, NaCl, and nonfermen ted sugars. Tetracycline-resistant clones were derived from several P- fimbriated strains. The bacteria were tested for the ability to agglut inate erythrocytes, yeast cells, and alpha-D-Gal(-4)-beta-D-Gal-bonded latex (Gal-Gal) beads and were examined for fimbriae by electron micr oscopy. Hyperosmolar conditions decreased fimbrial expression for all strains. Expression of P fimbriae by pyelonephritic strains, all of wh ich were OmpF(+), was reversibly repressed by salicylate and bismuth s alts. CFA strains were similarly affected. Tetracycline-resistant P-fi mbriated strains were OmpF deficient, were unable to agglutinate eryth rocytes and Gal-Gal beads, and lacked fimbriae as observed by electron microscopy. Strains with plasmid-encoded P-fimbrial genes did not dem onstrate OmpF on polyacrylamide gel electrophoresis profiles and were not affected by salicylate. The type 1-fimbriated phenotype was not af fected by salicylate or bismuth unless the strains also expressed P fi mbriae. S-fimbriated strains were not affected. The mechanism by which salicylates, bismuth salts, and tetracycline resistance inhibit or mo dulate the expression of P fimbriae may be mediated through OmpF and o ther OMPs.