012-3-11 Pathogenesis(cont) Pathogenesis(cont) u When bacteria have reached the bl a The female urethra is short and allows transport of ia is facilitated by incom bacteria to the bladder in healthy individuals With many uropathogens, such tra is facilitated by bladder through the ureter to the renal pelvis and the renal adherence of the bacteria to urethral epithelial cells parenchyma. n Sexual intercourse results in increased numbers of a This transport may be facilitated b cteria in the periurethral area of the vagina and the mic defects of the ureters or the kidneys distal part of the urethra, increasing the risk of vesicoureteral reflux o adhesion to the ureter mucosa Pathogenesis(cont Bacterial virulence factors a Uropathogenic E Coli: a Whether bladder infection occurs depends a belongs to a small no of specific o, K and H serogroups on interacting effects of the pathogenicity n Easy to adherence to uroepithelial cells(fimbriae) D After attachment, initiates some important events in epithelial of the strain the inoculum size. and the local and systemic host defense mechanism a These properties are not needed for infection of the Bladder catheterization and utis Host factors complicating bacteriuria FACTORS s Bladder catheterization leads to bacteriuria or funguria in almost all patients who have had their catheters for more the growth of microorganisn a Urosepsis, resulting from diss acteria from the urine to the blood may ha or changing the catheter. infections involving the kidneys a The urethral mucosa may also be damaged by crystals Chronic pyelonephritis that form on the catheter surface2012-3-11 3 Pathogenesis(cont.) „ The female urethra is short and allows transport of bacteria to the bladder in healthy individuals. „ With many uropathogens such tr With many uropathogens, such transport ansport is facilitated by is facilitated by adherence of the bacteria to urethral epithelial cells. „ Sexual intercourse results in increased numbers of bacteria in the periurethral area of the vagina and the distal part of the urethra, increasing the risk of bacteriuria. Pathogenesis(cont.) „ When bacteria have reached the bladder, the establishment of bacteriuria is facilitated by incomplete bladder emptying „ Pyelonephritis results from ascending bacteriuria from the bladder through the ureter to the renal pelvis and the renal bladder through the ureter to the renal pelvis and the renal parenchyma. „ This transport may be facilitated by: … host factors such as anatomic defects of the ureters or the kidneys, vesicoureteral reflux … adhesion to the ureter mucosa Pathogenesis(cont.) „ Whether bladder infection occurs depends on interacting effects of the pathogenicity of the strain, the inoculum size, and the local and systemic host defense mechanism. Bacterial Virulence Factors „ Uropathogenic E. Coli: … belongs to a small no. of specific O, K and H serogroups. … Easy to adherence to uroepithelial cells (fimbriae) … After attachment initiates some i After attachment, initiates some important mportant events in epithelial events in epithelial cells(secretion IL6, IL8, induction of apoptosis and epithelial cell desquamation) … Secretion hemolysin and aerobactin and are resistant to the bactericidal action of human serum „ These properties are not needed for infection of the compromised urinary tract Host factors complicating bacteriuria Bladder catheterization and UTIs „ Bladder catheterization leads to bacteriuria or funguria in almost all patients who have had their catheters for more than 1 week. „ Formation of a biofilm on the catheter surfaces facilitates the gro th of microorganisms the growth of microorganisms. „ Urosepsis, resulting from disssemination of bacteria from the urine to the blood may happen during the removing or changing the catheter. „ The urethral mucosa may also be damaged by crystals that form on the catheter surface