012-3-11 Pregnancy and UTIs Pregnancy and UTls(cont a UTIs are detected in 2-8%of pregnant women. ition to upper tract infection during s Asymptomatic bacteriuria frequently harbor organisms that ess virulent than those causing symptomatic infections. n Temporary incompetence of the vesicoureteral valv m Fully 20-30% of pregnant women with asymptomatic a Bladder catheterization during or after delivery bacteriuria subsequntly develop pyelonephritis. a Risk of UTIs during pregnancy a Increased incidences of low-birth-weight infants 口 Premature delivery Genetic Factors and UTIs P blood group a Host genetic factors influence susceptibility to UTIs m P blood group system, classification of human blood based on the presence of any of three substances experienced recurrent Utis than among controls. known as the P. P, and Pk ans on the surfaces of s The number and type of receptors which bacteria may attach are at opart geneticaly a There are five phenotypes in the P blood group system: P, P2, P, P2, P a P2 phenotype -consists of the P and P< antigens a Many of these structures are components of blood group antigens and are present on both erythrocytes and o P, phenotype---Pk antigen o Extremely uroepithelial cel a p phenotype-no antigens unc ommon P blood group antigens assigned roles in the P blood group antigens assigned roles in the pathophysiology of UTIs pathophysiology of UTIs(cont) a The P blood group antigens are glycan structures, expressed not only on red cells, but also on other tissues, including the enotype has a higher risk, relative to P2 phenotype is of utis by the observation that various uropathogenic observation that adhesion of strains of Escherichia coli express adhesins that bind to the elonephritic strain of E. coli to renal tissue is mediated Gala1-4Gal moiety of the Pk and P, antigens acterial adhesin specific for the Gala 1-4Gal structure and that deficiency of the adhesin severely s The P, detern attenuates the pyelonephritic phenotype of the organism. attachment of bacteria to the lining of the urinary tracing individuals and may facilitate bacterial infection by media2012-3-11 4 Pregnancy and UTIs „ UTIs are detected in 2-8% of pregnant women. „ Asymptomatic bacteriuria frequently harbor organisms that less virulent than those causing symptomatic infections. „ Fully 20-30% of pregnant women with asymptomatic bacteriuria subsequntly develop pyelonephritis. Pregnancy and UTIs(cont.) „ The predisposition to upper tract infection during pregnancy results from: … Decreased ureteral tone … Decreased ureteral peristalsis Decreased ureteral peristalsis … Temporary incompetence of the vesicoureteral valve … Bladder catheterization during or after delivery „ Risk of UTIs during pregnancy … Increased incidences of low-birth-weight infants … Premature delivery … Newborn mortality Genetic Factors and UTIs „ Host genetic factors influence susceptibility to UTIs. „ A maternal history of UTI is more often found among women who have experienced recurrent UTIs than among controls. „ The number and type of receptors on uroepithelial cells to which bacteria may attach are at least in part genetically determined. „ Many of these structures are components of blood group antigens and are present on both erythrocytes and uroepithelial cells P blood group „ P blood group system, classification of human blood based on the presence of any of three substances known as the P, P1, and Pk antigens on the surfaces of red blood cells. „ There are five phenotypes in the P blood group system: P1, P2, P1 k, P2 k, P … P1 phenotype --- displays all three P antigens … P2 phenotype --- consists of the P and Pk antigens … P1 k phenotype -- P1 and Pk antigens … P2 k phenotype --- Pk antigen only … p phenotype --- no antigens Extremely uncommon P blood group antigens assigned roles in the pathophysiology of UTIs „ The P blood group antigens are glycan structures , expressed not only on red cells, but also on other tissues, including the urothelium . „ A role for P blood group antigens in the pathogenesis of UTIs is implied by the observation that various uropathogenic strains of Escherichia coli express adhesins that bind to the Galα1–4Gal moiety of the Pk and P1 antigens. „ The P1 determinant is expressed on the urothelium of P1 individuals and may facilitate bacterial infection by mediating attachment of bacteria to the lining of the urinary tract P blood group antigens assigned roles in the pathophysiology of UTIs (cont.) „ This hypothesis is supported by the observation that P1 phenotype has a higher risk, relative to P2 phenotype, for UTIs and pyelonephritis. „ It is also supported by the observation that adhesion of a pyelonephritic strain of E. coli to renal tissue is mediated by a bacterial adhesin specific for the Galα1–4Gal structure and that deficiency of the adhesin severely attenuates the pyelonephritic phenotype of the organism