012-3-11 Microbial Etiology of UTIs Epidemiology(cont NICAL CHARACTERISTICs a UTls is also the most common type of hospital-acquired infection because of the frequent use of bladder-catheters (catheter-associated infection) Most comcon daring sanmar Urethral syndrome Pathogenesis s In the vast majority of UTIs, bacteria gain access to the n About 1/3 n with dysuria and frequency have either an adder via the urethra m Ascent of bacteria from the bladder may follow and is mpletely sterile cultures -previously defined as having probably the pathway for most pyelonephritis urethral syndrome. a y no pyuria(and little objective evidence of infection) s In rare cases, bacteriuria and funguria may result from D Low counts(102 to 10ml)of typical bactenal uropathogens n These bacteria are probably the causative agents and associated with genous pyelonephritis occurs most often in ed patients who are either chronically ill or D Can be isolated from a suprapubic aspirate receiving immuno-suppresive therapy rimary focus of the infection is usually an infection at a site outside the renal tract, such as endocarditis Pathogenesis(cont Pathogenesis(cont s The vaginal introitus and distal urethra are normally colonized by diphtheroids, streptococcal and a In the normal male urethra. the distance between the staphylococcal species, lactobacilli, but not by the enteric G(-)bacilli end of the urethra and the bladder is too long to allow ding transport of bacteria to the bladder The factors that predispose to periurethral colonization with G()bacilli remain poorly understood. de when there is a turbulent urine flow a Alteration of the normal vaginal flora by antibiotics, other with a stricture or obstruction of the urethra. as a prostate hyperplasia, and when the patient has a appear to play an important role. n Loss of the normally dominant H2O2-producing ctobacilli in the vaginal flora appears to facilitate colonization by Ecoli2012-3-11 2 Epidemiology (cont.) „ UTIs is also the most common type of hospital-acquired infection because of the frequent use of bladder-catheters. (catheter- associated infection) Microbial Etiology of UTIs Urethral syndrome „ About 1/3 of women with dysuria and frequency have either an insignificant number of bacteria in midstream urine cultures or completely sterile cultures ---previously defined as having urethral syndrome. „ ¼ no pyuria (and little objective evidence of infection) „ ¾ pyuria … Low counts(102 to 104/ml) of typical bacterial uropathogens … These bacteria are probably the causative agents and associated with pyuria … Can be isolated from a suprapubic aspirate … Respond to appropriate antimicrobial therapy Pathogenesis „ In the vast majority of UTIs, bacteria gain access to the bladder via the urethra. „ Ascent of bacteria from the bladder may follow and is probably the pathway for most pyelonephritis. „ In rare cases, bacteriuria and funguria may result from In rare cases, bacteriuria and funguria may result from the hematogenous dissemination of bacteria to the kidneys. „ Hematogenous pyelonephritis occurs most often in debilitated patients who are either chronically ill or receiving immuno-suppresive therapy. „ Primary focus of the infection is usually an infection at a site outside the renal tract, such as endocarditis. Pathogenesis(cont.) „ The vaginal introitus and distal urethra are normally colonized by diphtheroids, streptococcal and staphylococcal species, lactobacilli, but not by the enteric G(-) bacilli. „ The factors that predispose to periurethral colonization with G(-) bacilli remain poorly understood. „ Alteration of the normal vaginal flora by antibiotics, other genital infections, or contraceptives (esp. spermicide) appear to play an important role. „ Loss of the normally dominant H2O2-producing lactobacilli in the vaginal flora appears to facilitate colonization by E.coli. Pathogenesis(cont.) „ In the normal male urethra, the distance between the end of the urethra and the bladder is too long to allow ascending transport of bacteria to the bladder. „ Transport is possible when there is a turbulent urine flow (such as with a stricture or obstruction of the urethra, as a result of prostate hyperplasia, and when the patient has a bladder catheter )