UTI and interstitial disease Flashcards
UTI routes of infection
1) Ascending infection from lower GI tract and perineal skin is the most common. Most common is E. coli. 2)Hematogenous infection is much less common. Occurs in setting of sepsis and endocarditis in debilitated patients. S aureus and group A strep common.
UTI virulence factors
1) Bacterial adhesion – certain strains of E. coli have “P” pili which allow for attachment to glycosphingolipid receptors on urothelial cells. These uropathogenic strains commonly cuase pyelonephritis. 2) Blood group- Persons with blood group P1 carry these uropathogenic strains more often than those with blood group P2
UTI host defense mechanisms
- Mechanical: Secretions of urethral glands, Mucosal factors, Hydrokinetic factors - urine flow, Functional “valve” between bladder and ureter that prevents retrograde flow. 2. Chemical: Urine (poor culture medium due to osmolality, pH and ammonia), antibacterial prostatic secretions, blood group Ags (P2>P1). 3. Immunological: IgA and complement. 4. cellular: PMNs and shedding urothelial cells
List predisposing factors for UTI
Females > Males, instrumentation (catheters), decreased urinary flow/stasis, calculi (kidney stones), vesical-ureteral reflux, pregnancy, diabetes, diseases of kidneys/urinary tract
Why are females more prone to UTIs
a. Shorter urethra. b. Urethra more easily irritated (“honeymoon cystitis”). c. Vagina and introitus likely to be colonized by bacteria. d. Post-menopause: Lack of estrogen enhances colonization of vagina
Causes of decreased urinary flow
a. Urinary tract obstruction b. Incomplete voiding c. Infrequent micturition d. Low flow e. Bladder/ureteral diverticula f. Neurologic diseases affecting bladder control
What is vesical - ureteral reflux
backflow of urine from bladder to ureters, renal pelvis
How does pregnancy predispose to UTI
As the uterus grows, its increased weight can block the drainage of urine from the bladder, causing an infection.
How does diabetes predispose to UTI
The presence of high glucose concentration in urine provides a rich culture medium for bacteria to grow
Clinical manifestations of UTI
bacteruria (scarring mostly occurs at <5yrs old). Urethra/vesical-urethral valve: - dysuria, difficulty voiding, incomplete emptying, incontinence. Bladder (cystitis): frequency and suprapubic pain. Ureters and kidneys (acute pyelonephritis): flank pain and abdominal tenderness, fever, chills, oliguria.
Symptoms of UTI in early childhood
nonspecific symptoms, irritability, convulsions
urinalysis and urine culture for UTI
urinalysis: Many WBC’s, WBC casts (pyelonephritis), RBC’s (variable). urine culture: usually > 100,000 bacteria/ml; always > 10,000 bacterial/ml
complications of UTI
Recurrence, Acute pyelonephritis, Renal/perinephric abscess, Papillary necrosis (diabetes), Staghorn calculi (Proteus), Chronic pyelonephritis/renal scarring
What is acute pyelonephritis
suppurative inflammation of the kidney and renal pelvis caused by bacterial infection (less often fungal).
Acute pyelonephritis pathology
Patchy, wedge-shaped regions of suppuration with microabscesses. b. Tubules filled with aggregates of PMNs
c. Tubular destruction. d. Interstitium – edema, PMNs, lymphs and plasma cells. e. Glomeruli preserved until late in course f. Papillary necrosis – especially in diabetics and obstructive pyelonephritisPatchy, wedge-shaped regions of suppuration with microabscesses. b. Tubules filled with aggregates of PMNs
c. Tubular destruction. d. Interstitium – edema, PMNs, lymphs and plasma cells. e. Glomeruli preserved until late in course f. Papillary necrosis – especially in diabetics and obstructive pyelonephritis
Causes of chronic pyelonephritis
Urinary tract obstruction and vesical-ureteral reflux
How does urinary tract obstruction cause chronic pyelonephritis
Predisposes to infection, makes difficult to eradicate infection, predisposes to recurrence, combo of obstruction and infection causes structural damage with loss of renal function (due to pressure induced ischemia and tubular atrophy)
Causes of urinary tract obstruction
Intrinsic mass (calculi, tumors, clots), inflammation, urethral valves, extrinsic compression (tumors, fibrosis, hemorrhage, surgical ligation), functional (neuro disease or diabetes), idiopathic
What is nephrolithiasis
urinary outflow obstruction due to renal stones and hydronephrosis (water retention in kidney)
Consequences of obstruction of urinary tract
Hydronephrosis (dilation of urinary collecting system), tubular atrophy, Infection (Acute or Recurrent / persistent), Chronic obstructive pyelonephritis, decreased GFR, Renal failure, Hypertension
What is vesical-ureteral reflux
Retrograde flow of urine from bladder into ureter and renal pelvis during micturition
Structural changes in vesical-ureteral reflux
There is no anatomical valve, but normally the oblique course of the ureter through the bladder wall forms an effective “valve” in which the ureter is compressed duringincreased intravesicular pressure (micturition). A shortened or displaced intramural segment causing it to enter bladder perpendicularly allows reflux
Types of vesical-ureteral reflux
primary: congenital, common in infants and decreases in severity during childhood. Usually mild. Secondary: congenital malformations, obstructions, older children and adults
Grades of vesical-ureteral refulx
grade 1 has normal orifice. Grade 2 has stadium orifice (slightly enlarged). Stage 3 has golf hole orifice (large)
consequences of vesical-ureteral reflux
chronic or recurrent infections with non-obstructive pyelonephritis and renal scarring, termed reflux nephropathy
Pathology of reflux nephropathy
a. Coarse, segmental scars lying directly over dilated calyces. - Thinning of both cortex and medulla, Often unilateral or unequally bilateral. Scarring is more extensive at poles of kidney due to the presence of more compound papilla which have open ducts of Billini allowing for reflux. Some develop focal segmental glomerulosclerosis
