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UTIEbadur RahmanFRCP (Edin),FASN, Specialty Certificate in Nephrology (UK)MRCP (UK), DIM (UK), DNeph (UK), MmedSciNephrology (UK).Consultant & clinical tutorDepartment of NephrologyRiyadh Armed Forces Hospital

Urinary Tract Infection (UTI)Background1.Bacterial infections of urinary tract are a very common reason to seek health services2.Common in young females(50%) and uncommon in males under age 503.Common causative organismsa.Escherichia coli (gram-negative enteral bacteria) causes most community acquired infectionsb.Staphylococcus saprophyticus, gram-positive organism causes 10 15%c.Catheter-associated UTIs caused by gram-negative bacteria: Proteus, Klebsiella, Seratia, PseudomonasNatural protectionNormal mechanisms that maintain sterility of urineAdequate urine volumeFree-flow from kidneys through urinary meatusComplete bladder emptyingNormal acidity of urinePeristaltic activity of ureters and competent ureterovesical junctionIncreased intravesicular pressure preventing refluxIn males, antibacterial effect of zinc in prostatic fluidIGA in urogenital tract

Pathophysiology

1.Pathogens which have colonized urethra, vagina, or perineal area enter urinary tract by ascending mucous membranes of perineal area into lower urinary tractBacteria can ascend from bladder to infect the kidneysHEMATOGENOS ROUTE

Reinfection is a new episode of bacteriuria with a microorganism that is different from the original one (eg, bacteriuria with Klebsiella species when the original infection was caused by E coli). Recurrence is infection that usually occurs within 2 weeks of stopping antibiotic therapy with same organism.

To obtain a clean-catch, midstream specimen, the urethral opening is washed with a mild, nonfoaming disinfectant and air dried. Contact of the urinary stream with the mucosa should be minimized by spreading the labia in women and by pulling back the foreskin in uncircumcised men. The first 5 mL of urine is not captured; the next 5 to 10 mL is collected in a sterile container.

A specimen obtained by catheterization is preferable in older women

culture, should be done within 2 h of specimen collection; if not, the sample should be refrigerated.

Microscopic examination Pyuria is defined as 8 WBCs/L of uncentrifuged urine, which corresponds to 2 to 5 WBCs/high-power field in spun sediment. Most truly infected patients have > 10 WBCs/L. The presence of bacteria in the absence of pyuria, especially when several strains are found, is usually due to contamination during sampling. Microscopic hematuria occurs in up to 50% of patients, but gross hematuria is uncommon. WBC casts, can be present in pyelonephritis, and noninfective tubulointerstitial nephritis

Sterile pyuriaPyuria in the absence of bacteriuria if patients have nephrolithiasis, a uroepithelial tumor, TB Women who have dysuria and pyuria but without significant bacteriuria have the urethral syndrome or dysuria-pyuria syndrome

Dipstick tests A positive nitrite test on a freshly voided specimen is highly specific for UTI, but the test is not very sensitive. The leukocyte esterase test is very specific for the presence of > 10 WBCs/L and is fairly sensitive.

For outpatient treatment of uncomplicated pyelonephritis

ciprofloxacin (500 mg orally twice daily for seven days or 1000 mg extended release once daily for seven days) or levofloxacin (750 mg orally once daily for five to seven days) The bioavailability and urinary penetration of fluoroquinolones with oral dosing is comparable to intravenous dosing. In women who have severe pyelonephritis, and resistance suspected -IV therapy ceftriaxone (1 gram) or an aminoglycoside (consolidated 24 hour dose) .LOWER UTINitrofurantoin (100 mg orally twice daily for 5 days); 90 to 95 percent cure rateNitrofurantoin should be avoided if there is suspicion for early pyelonephritis, and is contraindicated when creatinine clearance is