Pathology of UTI Flashcards
What is the presentation of a UTI?
- Dysuria
- Frequency
- Smelly urine
Which groups of people may have a UTI and be unaware?
Very young- unwell, failure to thrive
Very old- incontinent anyways and may not notice
Do the ureters store urine?
No- they have continuous trickle of urine but do not store
How is reflux of urine from the ureter prevented?
Increasing pressure from the bladder as it fills closes off the ureter
What are some of the properties of normal urinary tracts which help to limit infection?
Prostatic bacteriostatic secretion
Low pH
High osmolarity
High ammonia content of urine
Anti-bacterial antibodies
What is the only part of the urinary tract which is not sterile?
Terminal urethra and perianal skin
Usual urine samples are always contaminated by terminal urethra flora.
How could a sterile urine sample be taken if required?
Suprapubic aspiration of urine
What is urinary voiding?
Process of removing urine from the body
If you send a urine specimen for culture, the initial void is heavily contaminated by urine.
What can be done to prevent this?
Patient voids and then stops mid-stream, discarding the initial urine output which is heavily contaminated, and then collects the next volume of urine
MSSU?
Mid-stream specimen of urine
->this is what is tested as has far less bacteria
In a MSSU, will there be urethral flora in it?
Yes but will be far less than initial urine output
This urethral flora is diminished in the lab as normal
In which phase of growth do bacteria muliply?
Log phase
->I think this could be something covered in higher bio tbh
What quantity of bacteria usually suggests infection in MSSU culture?
10 to power of 5
->99/100 with these level will have an infection
If someone has an MSSU culture of 10 to the power of 3 or 4, could they have a UTI?
Yes, probable infection but most often when they have symptoms
Be aware they could be asymptomatic and have these results and still have one tho
MSSU culture of what usually means no infection?
<10 to power of 3
Who can it be difficult to get a MSSU sample from?
Young children and elderly
What is on of the problems with interpretation of urine cultures?
Some bacterial species are not normally present in terminal urethra/rectal flora and may be pathogenic at low colony numbers
What organisms usually cause UTIs?
Bacteria, like gut flora.
Especially E.coli
Is the route of infection in UTI’s usually ascending or descending?
Ascending
If there is infection of the kidneys, where has the infection usually spread from?
Bladder
If the infection is in the upper urinary tract, is this more or less serious?
More
Infection of urethra?
Urethritis
Infection of bladder wall?
Cystitis
Infection of ureter?
Ureteritis
Bacterial infection of kidney?
Acute pyelonephritis
What are some of the predisposing factors for a UTI?
-Stasis of urine (inactivity)
-Pushing bacteria up urethra from below
-Generalised predisposition to infection
What can cause stasis of urine?
Obstruction
Loss of feeling e.g. unable to tell when bladder is full
What can result in pushing bacteria up from the urethra?
Sexual activity in females
Catheterisation or other urinary procedures
What could give someone a predisposition to developing infection?
Diabetes
Why does stasis of urine lead to UTI?
Bacteria is not flushed out
What happens if there is obstruction to the urinary system at the level of the urethra?
Upper urethral dilatation -> bladder dilatation -> ureteric dilatation (bilateral hydroureter)
What can happen as a result of bilateral hydroureter?
Kidneys enlarge and can cause chronic renal failure
What would happen if there was obstruction of the urinary tract at the level of the renal pelvis on one side only?
Unilateral hydroureter
This can then develop into unilateral hydronephrosis
Hydronephrosis?
Hydronephrosis is a condition where one or both kidneys become stretched and swollen due to build-up of urine inside them
What are the consequences of obstruction of the urinary system?
Proximal dilatation
Slowed urine flow -> cannot flush out bacteria -> infection
Slowed urine flow -> sediments from calculous formation -> further obstruction -> further infection
What is the triad of obstruction and UTI?
Cycle of:
Infection -> Calculi -> Obstruction -> Infection etc.
What is the most important example of obstruction of the urinary system in children?
Vesicoureteric reflux
When urine moves backwards from the bladder to the kidneys
->often those w vesicouretic reflux are born w it
What happens in vesicoureteric reflux?
Decreased angle of the ureter inserting into the bladder hence backflow of urine as cannot get into bladder as efficiently
What is the most common cause of urinary obstruction in adult males?
Benign prostatic hyperplasia
Tumours and calculi are causes too
What is the most common cause of urinary obstruction in adult females?
Uterine prolapse
Tumours and calculi are causes too
What is loss of feeling of full bladder due to?
Brain or spinal cord injury
What are some predisposition to UTI’s in females?
Short urethra
Lack of prostatic bacteriostatic secretion (as only happens in males)
Closeness of urethral orifice to rectum
Sexual activity (helps if void after intercourse)
Pregnancy as pressure on ureters and bladder
What is an acute complication of a UTI?
Severe sepsis and septic shock
What are some of the chronic complications of a UTI?
Chronic damage to kidneys if repeated infections
Chronic renal failure
Hypertension
