BACTERIAL FACTORS IN THE FORMATION OF RENAL SCARS - AN EXPERIMENTAL-STUDY ON THE ROLE OF ESCHERICHIA-COLI P-FIMBRIATION AND HYDROPHOBICITY

A model capable of comparing the effects of bacterial virulence factor s on renal scarring in vivo has been developed using the female piglet . By creating, at open surgery, unilateral vesicoureteric reflux (VUR) and quantifying scarring both by uptake of an isotope bound to functi oning renal parenchyma and by planimetry of the surface area scarred, the effects of 2 organisms, a P-fimbriate Escherichia coli and an E. c oli K1 have been compared. The P-fimbriate E. coli was shown to expres s P-fimbriae in freshly voided urine, was more hydrophobic and produce d smaller scars. This indicates that neither the hydrophobicity nor P- fimbriation of the organism causing urinary tract infection (UTI) is o f prime importance for the development of renal scars and is evidence against the ''big bang'' theory for the development of renal scars. St udies on the association of UTI with VUR showed that infection with bo th E. coli under study led to VUR on the side contralateral to the sid e undergoing surgery. It seems likely that a non-specific effect of UT I, such as bladder oedema, is responsible for this acquired VUR. An ef fect of the 2 bacteria under study on the lower urinary tract was obse rved in that infection with the P-fimbriate E. coli allowed the retent ion of an intravesical wax plug, whereas infection with E. coli K1 did not. Epidemiological data have shown that the majority of upper urina ry tract infections in children are associated with UTI by P-fimbriate organisms. Such an association may be explained in part by an effect of P-fimbriate bacteria on lower urinary tract function rather than an effect on the upper urinary tract.