urinary tract infection (UTI)

• DEFINITIONS: UTI is the microbial invasion ofany tissue of the urinary tract, extending fromthe urethral meatus to the renal cortex.

• Categories: upper tract infections ( pyelonephritis: fever, flank pain + dysuriaand frequency), lower tract infection ( cystitis: dysuria, frequent passage of smallvolumes of urine), acute urethral syndrome

• Asymptomatic bacteriuria is the colonization ofthe urinary tract in the absence of symptoms. Itis usually defined by the presence of greaterthan 105 colonies per ml of urine.

The urin sediment

Diagnostic testing:

Urinanalysis of thecentrifugated urin sediment: upper limit: 5-10 WBC/ highpower field on microscopeevalutaion

The presence of WBC casts is indicative for uper tractinfection

Dipstick test for nitrit is highlyspecific for infection

Urin culture: sign. bacteriuriadefined as more than 105/ml ofa single organism in culture ofa clean-catch midstream urinespecimen

Other forms of UTI

• Chronic pyelonephritis: chronic interstitial nephritis resultedfrom chronic ascending bacterial infection

• Papillary necrosis: infection of the renal pyramids seenmostly in diabetic patients. Symptomes:haematuria, flank pain, chills,fever, acute renal failure. X-ray finding: ring shadow on ivpyelography. Nephrectomy might be life saving

• Perinephric and renal abscesses: a complication ofbacterial pyelonephritis. Predisposing conditions: diabetes, nephroliths causing local obstruction of urinary flow, immunodeficiency. Suspition for this complication should arise whenpatient cured for acute pyelonephritis remain febrile after 5 days. Urine culture yields a polymicrobial flora. US or CT useful in thediagnosis. Treatment: drainage of pus, antibiotic diretcted at theorganisms recovered