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?)