Lecture 9 Pathology of Urinary Tract Infection

Question 1

UTI presenting symptoms

Answer 1

• Dysuria (pain on micturition)
• Frequency
• Smelly urine
• Very young- unwell, failure to thrive
• Very old- incontinence, off their feet

Question 2

How is urine samples for culture

Answer 2

Patient voids and stops mid-stream (initial void heavily contaminated), discarding urine, then collects next volume of urine = MSSU (mid-stream specimen of urine)

Question 3

What are the bacteriostatic properties of urine

Answer 3

Low pH
High osmolality
High ammonia

Question 4

Is the urinary tract sterile

Answer 4

Yes, except for terminal urethra

Question 5

A MSSU culture – 10^5 is usually

Answer 5

An infection

Question 6

MSSU culture – 10^3 10^4 is

Answer 6

Sometimes an infection is patient has symptoms

50% chance in no symptoms

Question 7

MSSU culture – <10^3

Answer 7

usually no infection

Question 8

What is a imitation of urine culture

Answer 8

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

Question 9

Micro-organisms that cause UTIs

Answer 9

Gut flora- E.coli

Question 10

Describe the route of infection for UTIs

Answer 10

Almost always ascending

Question 11

What are the inflammatory responses in these organs:
•	Urethra – 
•	Bladder – 
•	Ureter – 
•	Kidney – 
•	Kidney – if recurrent/prolonged 

UTI- predisposing Factors

Answer 11

• Urethra – urethritis
• Bladder – cystitis
• Ureter – ureteritis
• Kidney – acute pyelonephritis
• Kidney – if recurrent/prolonged infection chronic pyelonephritis

UTI- predisposing Factors

Question 12

Name predisposing factors of UTIs

Answer 12

• Stasis of urine- bacteria that do get higher up do not get dlushed out
– Obstruction,
– Loss of ‘feeling’ (sensory loss) of full bladder
– Sexual activity in females
– Catheterisation (and other urological procedures)
– Diabetes

Question 13

What are the consequences of obstruction at the level of the urethra

Answer 13

1. Upper urethral and bladder dilatation
2. Bilateral hydroureter
3. Bladder dilatation, bilateral hydroureter and bilateral hydronephrosis  chronic renal failure

Question 14

What are the consequences of obstruction at level of renal pelvis at one side only

Answer 14

1. Unilateral hydroureter

2. Unilateral hydroureter and unilateral hydronephrosis

Question 15

What is the triad of obstruction

Answer 15

Infection–>Calculi–>Obstruction–>

Question 16

Whats the most important example of obstruction in children

Answer 16

vesicoureteric reflux- due to decreased insertion angle of ureter

Question 17

Common causes of obstruction in adults

Answer 17

• Men – Benign Prostatic Hyperplasia (not a tumour) of prostate – functional and anatomical obstruction
• Women – uterine prolapse
• Both sexes – tumours and calculi

Question 18

How are females predisposition to have UTIs

Answer 18

Short urethra
Lack of prostatic bacteriostatic secretion
Closeness of urethral orifice to rectum
Sexual activity
Pregnancy- pressure on ureters and bladder

Question 19

What are the complications of UTI

Answer 19

• Acute: severe sepsis and septic shock
• Chronic:
– Chronic damage to kidneys if repeated infections (chronic pyelonephritis)  hypertension, chronic renal failure
– Calculi  obstruction  Hydronephrosis  hypertension, chronic renal failure