Urinary tract infection

urinary tract infection (UTI)
• DEFINITIONS: UTI is the microbial invasion of
any tissue of the urinary tract, extending from
the urethral meatus to the renal cortex.
• Categories: upper tract infections (
pyelonephritis: fever, flank pain + dysuria
and frequency), lower tract infection (
cystitis: dysuria, frequent passage of small
volumes of urine), acute urethral syndrome
• Asymptomatic bacteriuria is the colonization of
the urinary tract in the absence of symptoms. It
is usually defined by the presence of greater
than 105 colonies per ml of urine.
The urin sediment
Diagnostic testing:
Urinanalysis of the
centrifugated urin sediment:
upper limit: 5-10 WBC/ high
power field on microscope
evalutaion
The presence of WBC casts is
indicative for uper tract
infection
Dipstick test for nitrit is highly
specific for infection
Urin culture: sign. bacteriuria
defined as more than 105/ml of
a single organism in culture of
a clean-catch midstream urine
specimen
Other forms of UTI
• Chronic pyelonephritis: chronic interstitial nephritis resulted
from chronic ascending bacterial infection
• Papillary necrosis: infection of the renal pyramids seen
mostly in diabetic patients. Symptomes:haematuria, flank pain,
chills,fever, acute renal failure. X-ray finding: ring shadow on iv
pyelography. Nephrectomy might be life saving
• Perinephric and renal abscesses: a complication of
bacterial pyelonephritis. Predisposing conditions: diabetes,
nephroliths causing local obstruction of urinary flow,
immunodeficiency. Suspition for this complication should arise when
patient cured for acute pyelonephritis remain febrile after 5 days.
Urine culture yields a polymicrobial flora. US or CT useful in the
diagnosis. Treatment: drainage of pus, antibiotic diretcted at the
organisms recovered