Pathology of UTI Flashcards

1
Q

How do UTIs usually present?

A
  • Dysuria
  • Frequency
  • Smelly urine
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2
Q

Dysuria

A

Pain on micturition

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3
Q

How can a UTI present in the very young?

A
  • Unwell

- Failure to thrive

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4
Q

How can a UTI present in the elderly?

A
  • Incontinence

- Off their feet

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5
Q

What percentage of CO accounts for renal blood flow?

A

20-25%

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6
Q

What does urine output change with in the normal renal tract?

A

Oral intake of fluids

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7
Q

Why is there reduced resorption of fluid if theirs increased fluid intake?

A

There is increased urine output

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8
Q

How does urine from the kidneys reach the bladder?

A

There is a continuous trickle of urine through the ureters

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9
Q

How do the ureters enter the bladder?

A

At an angle

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10
Q

How is reflux of urine up the ureters prevented?

A

Increasing pressure from the filling bladder closes off the ureter/

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11
Q

What are the bacteriostatic properties of the normal urinary tract?

A

Free flow of urine through normal anatomy (assumes drinking enough fluids)

  • Low pH, high osmolality, and high ammonia (NH3) content of normal urine
  • Prostatic secretions are bacteriostatic
  • Anti-bacterial antibodies
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12
Q

What parts of the urinary tract are sterile?

A

All of the urinary tract apart from the terminal urethra

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13
Q

Why is the terminal urethra not sterile?

A

Skin (perineal) and gut (rectal) flora means it is not sterile

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14
Q

What type of aspirate would be sterile?

A

Suprapubic

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15
Q

What is urinated specimen always contaminated by?

A

Urethral flora

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16
Q

What will initial voiding do?

A

Flush out many terminal urethral flora bacteria

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17
Q

How should urine for culture be collected?

A

MSSU

-Patient voids and stops mid-stream, discarding urine, then collects next volume of urine

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18
Q

What does MSSU stand for?

A

Mid stream specimen urine

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19
Q

What is always present in MSSU?

A

Urethral flora but it is diminished

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20
Q

What will always grow in culture?

A

Urethral flora

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21
Q

How can contamination be differentiated from real infection in MSSU culture?

A

Cultured under set conditions and bacteria multiply in log phase growth

  • 10^5 usually infection
  • 10^3> 10^4 sometimes infection, probable if symptomatic (50% chance if no symptoms)
  • <10^3 usually no infection
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22
Q

Who is it difficult to collect MSSU from?

A

Young children and the elderly

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23
Q

What problems are there with interpreting urine culture?

A

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

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24
Q

What organisms cause UTIs?

A
  • Bacteria mostly gut flora and especially E coli

- Viral infections are rare

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25
Q

What is the route of infection almost always?

A

Ascending

26
Q

Where have kidney infections usually spread from?

A

Bladder

27
Q

Infection of what part of the urinary tract is more serious?

A

Upper urinary tract

28
Q

What is inflammation of the urethra called?

A

Urethritis

29
Q

What is inflammation of the bladder called?

A

Cystitis

30
Q

What is inflammation of the ureters called/?

A

Ureteritis

31
Q

What is inflammation of the kidney called?

A

Acute pyelonephritis

32
Q

What is inflammation of the kidneys called if there is recurrent/prolonged infection?

A

Chronic pyelonephritis

33
Q

What does infection lead to?

A

Inflammatory response

34
Q

What are the predisposing factors fro UTI?

A
  • Stasis of urine
  • Pushing bacteria up urethra from below
  • Generalised predisposition to infection
35
Q

What can cause stasis of urine?

A
  • Obstruction, whether congenital (presents in childhood) or acquired (adults).
  • Spinal cord/brain injury, loss of ‘feeling’ of full bladder -
36
Q

What can cause bacteria to be pushed up the urethra from below?

A
  • Sexual activity in females

- Catheterisation (and other urological procedures)

37
Q

Give an examples of a generalised predisposition to infection.

A

Diabetes mellitus

38
Q

Why can stasis of urine cause UTI?

A

Bacteria that do get higher up do not get flushed out

39
Q

What does obstruction at the level of the urethra lead to?

A
  • Upper urethral and bladder dilatation
  • Bilateral hydroureter
  • Bilateral hydronephrosis leading to chronic renal failure
40
Q

What can obstruction of the renal pelvis unilaterally cause?

A
  • Unilateral hydroureter

- Unilateral hydronephrosis

41
Q

What are the consequences of obstruction?

A
  • Proximal dilatation
  • Slowed urine which cannot flush out bacteria leading to infection
  • Slowed urine flow leading to sediment formation can calculous (stone) formation causing obstruction
42
Q

What can some bacterial infections predispose to?

A

Calculous formation

43
Q

What is the triad of the consequence of obstruction?

A
  • Infection
  • Calculi
  • Obstruction
44
Q

When should children be investigated?

A

Always investigate at 1st presentation and send to paediatric surgeons as there are numerous renal tract abnormalities

45
Q

What is the most important renal tract abnormality?

A

Vesicoureteric reflux

46
Q

What causes Vesicoureteric reflex?

A

Decreased angulation of the ureter when entering the bladder

47
Q

What does Vesicoureteric reflux cause?

A

Hydroureter

48
Q

What is a common cause of obstruction in men?

A

Benign prostatic hyperplasia (not a tumour) of prostate. It is a functional and anatomical obstruction

49
Q

What is a common cause of obstruction in women?

A

Uterine prolapse

50
Q

What are common causes of obstruction in adult males and females?

A
  • Tumours

- Calculi

51
Q

How does spinal cord/brain injury lead to stasis of urine?

A
  • Decreased sensation
  • No sense of when to micturate and do not know to empty bladder completely
  • Leave urine in bladder (high residual volume)
  • Stasis of urine
52
Q

Why does sexual activity lead to UTI in females?

A

In females sexual activity tends to move lower urethral flora up the tract (back wall of urethra is just in front of vagina)

53
Q

Why do females of any age have a predisposition to UTIs?

A
  • Short urethra
  • Lack of prostatic bacteriostatic secretion
  • Closeness of urethral orifice to rectum
  • Sexual activity – (helps if void after intercourse)
  • Pregnancy – pressure on ureters and bladder
54
Q

What can instrumentation of the urinary tract do?

A

Move lower urethral flora up the tract

55
Q

Why are diabetic more likely to get UTIs?

A
  • Glucose in urine

- Poor function of WBC

56
Q

What is the most common cause of UTIs in the early years?

A

Congenital abnormalities

57
Q

What is the most common cause of UTI in teenage and young females?

A

Sexual activity

58
Q

What is the most common causes of UTI in older adults?

A
  • Men: prostate problems
  • Women: uterine prolapse
  • Both sexes: Tumours
59
Q

What is an acute complication of UTI?

A

Severe sepsis and septic shock

60
Q

What are chronic complications of UTI?

A
  • Chronic damage to kidneys if repeated infections (chronic pyelonephritis) leading to hypertension and chronic renal failure
  • Calculi can cause obstruction and hydronephrosis which can result in hypertension and chronic renal failure
61
Q

What is the key question in UTI?

A

Why has the patient presented now?