URINARY TRACT STRUCTURE &
INFECTION
Innervation of the Urinary Tract
• Sympathetic fibers from the lower splanchnic nerves – lumbar ganglion – kidney
• Parasympathetic vagal fibers via the coeliac plexus• Regulation vasomotor tone, renal blood flow• Stimulation – causes intrarenal vasoconstriction and
reduces renal blood flow,
enhances Na reabsorption
stimulates local RAAS• Both sympathetic and parasympathetic nerve fibers
supply the ureter, vesica urinaria
Infection of the Urinary Tract
• Asymptomatic bacteriuria,
presence of bacteria in UT, absence of symptoms,
colonization from female periurethral area• Significant bacteriuria = > 100.000 bct/ ml
in 2 voided specimens or 1 in-out catheter specimen in a woman, or 1 voided specimen in a man
• Treatment only when risk factors for potential complicated UTI, eg pregnancy,
Acute UTI• Lower UTI : dysuria, frequency, urgency.• Upper UTI : infection involving the kidney• Complicated, uncomplicated• Clinical presentation in children more variable and frequently
nonspecific• Cystitis• Prostatitis, urethritis• Acute bacterial Pyelonephritis: bacterial invasion of the kidney,
clinical syndrome w/ chills and fever, flank pain, constitutional symptoms• Chronic pyelonephritis, path ~ tubulointerstitial nephritis caused by # of disorders: VUR, chronic obstructive uropathy, drugs & toxins, renal medullary ds, chronic / recurrent renal bacteriuria• Complicated infection :abnormal anatomy, obstruction, dilatation & impaired drainage risk of renal damage, abcess formation,septicemia
85% 50%
Urease
• Proteus mirabilis, P vulgaris, S saprophyticus• Involved in tissue adherence• Splitting urea into into CO2 & Ammonia• Urinary alkalinization• Precipitation of Mg, NH4, PO4• Stone formation, struvite
Investigation of UTI
• Dx: Microbiological: bacterial count >10 CFU /ml• Midstream urine collection• Women, introitus should be cleaned with NaCl,
midstream urine is collected with the labia spread apart• Suprapubic aspiration ( infants % children )• Urine can be stored at 4’C for up to 48h before culture• Infection may be present CFU 10 - 10• Mixed culture w/ low colony counts in F ~ contamination• Urinalysis ~first line screen, nitrates, leucocytes + hematuria, proteinuria• Urine microscopy, white cell casts ~ renal parenchymal
infection
5
2 5
ObstructionsProstate, Urethral stricture
Congenital anomalies Of urinary tract:Reflux, urethral valves
IVP
Abscess
Displacement / lateral ectopiaOf the ureteric orifice, Loss of valve like action
Treatment of UTI
• Most cases, uncomplicated lower UTI, 3 day course of antibiotics, no culture needed
Trimethoprim, cephalexin, amox/clavulanate, ciprofloxacin• Relapsing infections , 10 – 14 days if persist / recurs, further investigation• Prophylactic low dose antibiotics for recurrent, >3x/y UTI• In patients w/ clear relation between infection and sexual
activity, single dose after intercourse may be effective• Acute pyelonephritis ~ Rx in Hospital, IV fluids &
antibiotics started before culture results• Antibiotics IV – oral , 2 weeks• If no improvement in 48H, review AB, further investigation
(obstruction, abscess?)
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