UTI and interstitial disease

Question 1

UTI routes of infection

Answer 1

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.

Question 2

UTI virulence factors

Answer 2

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

Question 3

UTI host defense mechanisms

Answer 3

1. 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

Question 4

List predisposing factors for UTI

Answer 4

Females > Males, instrumentation (catheters), decreased urinary flow/stasis, calculi (kidney stones), vesical-ureteral reflux, pregnancy, diabetes, diseases of kidneys/urinary tract

Question 5

Why are females more prone to UTIs

Answer 5

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

Question 6

Causes of decreased urinary flow

Answer 6

a. Urinary tract obstruction b. Incomplete voiding c. Infrequent micturition d. Low flow e. Bladder/ureteral diverticula f. Neurologic diseases affecting bladder control

Question 7

What is vesical - ureteral reflux

Answer 7

backflow of urine from bladder to ureters, renal pelvis

Question 8

How does pregnancy predispose to UTI

Answer 8

As the uterus grows, its increased weight can block the drainage of urine from the bladder, causing an infection.

Question 9

How does diabetes predispose to UTI

Answer 9

The presence of high glucose concentration in urine provides a rich culture medium for bacteria to grow

Question 10

Clinical manifestations of UTI

Answer 10

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.

Question 11

Symptoms of UTI in early childhood

Answer 11

nonspecific symptoms, irritability, convulsions

Question 12

urinalysis and urine culture for UTI

Answer 12

urinalysis: Many WBC’s, WBC casts (pyelonephritis), RBC’s (variable). urine culture: usually > 100,000 bacteria/ml; always > 10,000 bacterial/ml

Question 13

complications of UTI

Answer 13

Recurrence, Acute pyelonephritis, Renal/perinephric abscess, Papillary necrosis (diabetes), Staghorn calculi (Proteus), Chronic pyelonephritis/renal scarring

Question 14

What is acute pyelonephritis

Answer 14

suppurative inflammation of the kidney and renal pelvis caused by bacterial infection (less often fungal).

Question 15

Acute pyelonephritis pathology

Answer 15

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

Question 16

Causes of chronic pyelonephritis

Answer 16

Urinary tract obstruction and vesical-ureteral reflux

Question 17

How does urinary tract obstruction cause chronic pyelonephritis

Answer 17

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)

Question 18

Causes of urinary tract obstruction

Answer 18

Intrinsic mass (calculi, tumors, clots), inflammation, urethral valves, extrinsic compression (tumors, fibrosis, hemorrhage, surgical ligation), functional (neuro disease or diabetes), idiopathic

Question 19

What is nephrolithiasis

Answer 19

urinary outflow obstruction due to renal stones and hydronephrosis (water retention in kidney)

Question 20

Consequences of obstruction of urinary tract

Answer 20

Hydronephrosis (dilation of urinary collecting system), tubular atrophy, Infection (Acute or Recurrent / persistent), Chronic obstructive pyelonephritis, decreased GFR, Renal failure, Hypertension

Question 21

What is vesical-ureteral reflux

Answer 21

Retrograde flow of urine from bladder into ureter and renal pelvis during micturition

Question 22

Structural changes in vesical-ureteral reflux

Answer 22

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

Question 23

Types of vesical-ureteral reflux

Answer 23

primary: congenital, common in infants and decreases in severity during childhood. Usually mild. Secondary: congenital malformations, obstructions, older children and adults

Question 24

Grades of vesical-ureteral refulx

Answer 24

grade 1 has normal orifice. Grade 2 has stadium orifice (slightly enlarged). Stage 3 has golf hole orifice (large)

Question 25

consequences of vesical-ureteral reflux

Answer 25

chronic or recurrent infections with non-obstructive pyelonephritis and renal scarring, termed reflux nephropathy

Question 26

Pathology of reflux nephropathy

Answer 26

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