Lecture 8 - Pathology of Urinary Tract Infection

Question 1

How does UTI tend to present?

Answer 1

Dysuria Frequency Smelly urine

Question 2

Define dysuria

Answer 2

Pain on urination

Question 3

How might very young people with UTIs present differently?

Answer 3

May present being unwell/FTT

Question 4

How might very old people with UTIs present differently?

Answer 4

Incontinence Off their feet

Question 5

What % of the CO becomes renal blood flow?

Answer 5

20-25%

Question 6

Do the ureters store urine?

Answer 6

No, they have a continuous trickle of urine down them

Question 7

Describe how the ureters enter the bladder?

Answer 7

At an acute angle

Question 8

How is the reflux of urine from the bladder into the ureters prevented in physiology?

Answer 8

Increasing pressure from bladder as it fills closes off the ureter

Question 9

What properties of the normal urinary tract make it bacteriostatic?

Answer 9

Free flow urine through normal anatomy Low pH, high osmolality and high ammonia in normal urine content Prostatic secretions are bacteriostatic Anti-bacterial antibodies

Question 10

Is the normal urinary tract sterile?

Answer 10

Yes expect from terminal urethra (perineal and rectal flora)

Question 11

Should a suprapubic aspirate of urine be sterile or not?

Answer 11

Should be sterile

Question 12

Should a urinated specimen be sterile?

Answer 12

No it will always be contaminated by terminal urethral flora

Question 13

What can get rid of a lot of the terminal urethral flora to allow you to get a less contaminated urine sample?

Answer 13

Initial voiding

Question 14

What is a MSSU?

Answer 14

Mid-stream specimen of urine Patient voids and then stops midstream, discards urine and collects next volume of urine

Question 15

In which groups of people can it be difficult to get an MSSU?

Answer 15

Young children Adults

Question 16

Is a MSSU sterile?

Answer 16

No - but urethral flora will be diminshed

Question 17

How do you tell MSSU contamination from infection?

Answer 17

Send to microbiology for culture under set conditions Bacteria multiply in log phase growth 10^5 usually indicates infection

Question 18

What does an MSSU of 10^3-10^4 indicate?

Answer 18

Symptomatic - probable infection Asymptomatic - 50% chance of infection

Question 19

What does an MSSU of <10^3 indicate?

Answer 19

Usually no infection

Question 20

What are issues with urine culture intrepretation?

Answer 20

Some bacterial species not normally present in urethral/rectal flora + may be pathogenic at low numbers

Question 21

What organisms tend to cause UTIs?

Answer 21

Gut flora, esp. E. coli

Question 22

What is the most common route of infection in UTI?

Answer 22

Almost always ascending (from urethra)

Question 23

What is the most common route of infection in a kidney infection?

Answer 23

Spread up from bladder

Question 24

What does the infection in a UTI lead to?

Answer 24

Inflammation (urethritis, cystitis, ureteritis, acute/chronic pyelonephritis)

Question 25

What are the 3 key predisposing factors that cause UTIs?

Answer 25

Stasis of urine Pushing bacteria up urethra from below Generalised predisposition to infction

Question 26

What things may cause stasis of urine?

Answer 26

Obstruction (congenital/acquired) Loss of feeling of full bladder, e.g. spinal cord/brain injury

Question 27

What things may cause pushing up of bacteria up the urethra from below?

Answer 27

Sex in females Catheterisation + other urological procedures

Question 28

Give an e.g. of something that generally predisposes to infection?

Answer 28

Diabetes

Question 29

Why does stasis of urine lead to UTIs?

Answer 29

Bacteria that do get higher up are not flushed out

Question 30

What happens if there is an obstruction to the urethra?

Answer 30

Upper urethral and bladder dilatation

Question 31

What can bladder dilatation result in?

Answer 31

Bilateral hydroureter

Question 32

What can bilateral hydroureter result in?

Answer 32

Bilateral hydronephrosis --\> chronic renal failure

Question 33

What occurs if there is obstruction at the level of the renal pelvis at one side only?

Answer 33

Unilateral hydroureter + hydronephrosis

Question 34

What are the consequences of blockages in the urinary tract?

Answer 34

Proximal dilatation Slowed urine flow --\> cannot flush out bacteria --\> infection Slowed urine flow --\> sediments form --\> calculous formation --\> obstruction --\> more of the above!

Question 35

What tends to cause obstruction in children?

Answer 35

Renal tract abnormalities

Question 36

Should you always investigate UTIs in kids?

Answer 36

Yes, investigate at first presentation + send to paediatric surgeons

Question 37

What is the most important thing causing UTIs in kids?

Answer 37

Vesicoureteric reflux

Question 38

What is the pathophysiology of vesicoureteric reflux?

Answer 38

There is decreased angulation of the ureter as it enters the bladder This means urine can reflux when the bladder is full

Question 39

What are common causes of obstruction of the urinary tract in adults?

Answer 39

Men - BPH --\> enlarged prostate surrounding the urethra Women - urine prolapse Both - tumours, calculi

Question 40

Why can spinal cord/brain injury lead to stasis of urine?

Answer 40

Incomplete emptying of bladder due to reduced sensation so there is a higher residual volume --\> stasis of urine

Question 41

When do MEN tend to get UTIs?

Answer 41

Late middle age

Question 42

When do women tend to get more UTIs?

Answer 42

During sexually active years

Question 43

What gender is more predisposed to getting UTIs?

Answer 43

Women

Question 44

What happens during sex that makes women more prone to UTIs?

Answer 44

Sexual activity tends to move lower urethral flora up the tract

Question 45

Why are the female sex more predisposed to UTIs?

Answer 45

Shorter urethra Lack of prostatic bacteriostatic secretions Closeness of urethral orifice to rectum Sex Pregnancy - pressure on ureters and bladder

Question 46

Why are diabetics more prone to UTIs?

Answer 46

Glucose in urine Poor WBC function

Question 47

So, what tends to cause UTIs in: A. Children B. Young females C. Older males D. Older females

Answer 47

A. Urinary tract abnormalities B. Sexual activity C. Prostatic problems/tumours D. Uterine prolapse/tumours

Question 48

What are acute complications of UTIs?

Answer 48

Severe sepsis and septic shock

Question 49

What are chronic complications of UTIs?

Answer 49

Chronic damage to kidneys if repeated infection (chronic pyelonephritis) --\> HTN, chronic renal failure Calculi --\> obstruction --\> hydronephrosis --\> HTN, chronic renal failure