Pathology of Urinary Tract Infection

Question 1

What is the common presentation of a UTI?

Answer 1

Dysuria (pain on micturition), frequency and smelly urine
Very young - unwell and failure to thrive
Ver old - incontinence and off their feet

Question 2

What is renal blood flow equal to?

Answer 2

20-25% cardiac output

Question 3

How does urine output change with oral intake of fluids?

Answer 3

Reabsorption of fluid is diminished if increased fluid intake which increases urine output

Question 4

Does the ureters store urine?

Answer 4

No they do not store but have continuous trickle of urine

Question 5

Explain the importance of the ureter entering the bladder at an angle

Answer 5

Increasing pressure from bladder as it fills - closes off ureter and stops the reflux of urine

Question 6

What are some bacteriostatic properties of the normal urinary tract?

Answer 6

Free flow of urine in normal anatomy - assume enough fluids
Low pH, high osmolarity, and high ammonia content of urine
Prostatic secretions - Men
Antibacterial antibodies

Question 7

Which part of the normal renal tract is not sterile?

Answer 7

Terminal urethra
Perineal skin and gut flora

Question 8

What is a urinated specimen always contaminated with?

Answer 8

Terminal urethra flora

Question 9

Explain a collection of urine after initial void

Answer 9

Patient voids and stops mid-stream, discarding urine, then collects next volume of urine - MSSU (mid-stream specimen of urine)
This has far less bacteria from terminal urethra but still present

Question 10

Can there be a negative result in an MSSU?

Answer 10

No such thing as a negative result

Question 11

How is an MSSU analysed?

Answer 11

Microbiology of culture under set conditions
Bacteria multiply in log phase growth
Can do a dip slide method - look at bacteria colonies

Question 12

What value in MSSU culture usually means infections?

Answer 12

10^5 per ml

Question 13

What is 10^3 to 10^4 per ml on MSSU culture?

Answer 13

Infection sometimes
Probable infection if there are symptoms
50% chance if no symptoms

Question 14

What is less than 10^3 per ml on MSSU mean?

Answer 14

Usually no infection

Question 15

What is a problem with interpretation of urine culture?

Answer 15

Some bacterial species are not normally present in the terminal urethra/ rectal flora and may be pathogenic at low colony numbers

Question 16

What are the common micro-organisms which cause UTI?

Answer 16

Bacteria mainly - gut flora, esp. E.coli
Viral infection is rare

Question 17

What is the route of infection in UTI?

Answer 17

Usually always ascending
Infection from kidneys usually from bladder infection
Upper UTI is more serious

Question 18

What are inflammation of renal tract parts called?

Answer 18

Urethritis, cystitis, urethritis, and acute pyelonephritis
If recurrent/ prolonged then chronic pyelonephritis

Question 19

What are some predisposing factor of UTI?

Answer 19

Stasis of urine
Pushing bacteria up urethra from below
Generalised predisposition to infection - diabetes

Question 20

What can cause stasis of urine?

Answer 20

Obstruction - congenital or acquired
Loss of feeling (sensory loss) of full bladder

Question 21

What can cause pushing of bacteria up urethra from below?

Answer 21

Sexual activity in females
Catheterisation

Question 22

What can be the result of obstruction at level of urethra?

Answer 22

Upper urethral and bladder dilatation
Then if this continues - bilateral hydroureter (ureteric dilatation)
Then if continues - bilateral hydro-nephrosis - chronic renal failure

Question 23

What happens when there is obstruction of renal pelvis on 1 side only?

Answer 23

Unilateral hydroureter
If continues then get unilateral hydro-nephrosis
So still have a normal kidney at one side

Question 24

What are the consequences of obstrcution?

Answer 24

Proximal dilatation
Slowed urine flow - can’t flush out bacteria so infection
Also slowed urine flow - sediments form and then calculous form leading to obstruction - more infections, dilatation and calculous forming

Question 25

What is the triad of obstruction consequences?

Answer 25

Infection, calculi and obstruction

Question 26

Explain obstruction in children

Answer 26

Numerous renal tract abnormalities
Always investigate at 1st presentation and send to paediatric surgeons
Most important - vesicoureteric reflux

Question 27

Describe vesicourecteric reflux

Answer 27

Decreased angulation - so can get urine fluxing backwards even when bladder is full
Then get hydroureter

Question 28

What are common causes of obstruction in adults?

Answer 28

Men - benign prostatic hyperplasia of prostate - functional and anatomical obstruction
Women - uterine prolapse
Both sexes - tumours and calculi

Question 29

How does spinal cord/ brain injury cause a predisposition for UTI?

Answer 29

Decreased sensation - no sense to micturate and not know when empty bladder completely so leave urine in bladder so stasis of urine

Question 32

How does diabetes cause a predisposition to UTIs?

Answer 32

Glucose in urine and poor function of WBCs

Question 32

What is the predisposition of UTI for female sex?

Answer 32

Short urethra, lack of prostatic bacteriostatic secretion, closeness of urethral orifice to rectum, sexual activity and pregnancy

Question 33

What is an acute complication of UTI?

Answer 33

Severe sepsis and septic shock

Question 34

What are chronic complications of UTI?

Answer 34

Chronic damage to kidneys if repeated infections (chronic pyelonephritis) - hypertension and chronic renal failure
Calculi - obstruction - hydro-nephrosis - hypertension and chronic renal failure