Pathology of Urinary Tract Infection Flashcards

1
Q

What is the common presentation of a UTI?

A

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

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2
Q

What is renal blood flow equal to?

A

20-25% cardiac output

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3
Q

How does urine output change with oral intake of fluids?

A

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

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4
Q

Does the ureters store urine?

A

No they do not store but have continuous trickle of urine

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5
Q

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

A

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

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6
Q

What are some bacteriostatic properties of the normal urinary tract?

A

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

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7
Q

Which part of the normal renal tract is not sterile?

A

Terminal urethra
Perineal skin and gut flora

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8
Q

What is a urinated specimen always contaminated with?

A

Terminal urethra flora

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9
Q

Explain a collection of urine after initial void

A

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

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10
Q

Can there be a negative result in an MSSU?

A

No such thing as a negative result

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11
Q

How is an MSSU analysed?

A

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

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12
Q

What value in MSSU culture usually means infections?

A

10^5 per ml

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13
Q

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

A

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

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14
Q

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

A

Usually no infection

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15
Q

What is a problem with interpretation of urine culture?

A

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

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16
Q

What are the common micro-organisms which cause UTI?

A

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

17
Q

What is the route of infection in UTI?

A

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

18
Q

What are inflammation of renal tract parts called?

A

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

19
Q

What are some predisposing factor of UTI?

A

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

20
Q

What can cause stasis of urine?

A

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

21
Q

What can cause pushing of bacteria up urethra from below?

A

Sexual activity in females
Catheterisation

22
Q

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

A

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

23
Q

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

A

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

24
Q

What are the consequences of obstrcution?

A

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

25
Q

What is the triad of obstruction consequences?

A

Infection, calculi and obstruction

26
Q

Explain obstruction in children

A

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

27
Q

Describe vesicourecteric reflux

A

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

28
Q

What are common causes of obstruction in adults?

A

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

29
Q

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

A

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

30
Q
A
31
Q
A
32
Q

How does diabetes cause a predisposition to UTIs?

A

Glucose in urine and poor function of WBCs

32
Q

What is the predisposition of UTI for female sex?

A

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

33
Q

What is an acute complication of UTI?

A

Severe sepsis and septic shock

34
Q

What are chronic complications of UTI?

A

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