Lecture 9 Pathology of Urinary Tract Infection Flashcards
UTI presenting symptoms
- Dysuria (pain on micturition)
- Frequency
- Smelly urine
- Very young- unwell, failure to thrive
- Very old- incontinence, off their feet
How is urine samples for culture
Patient voids and stops mid-stream (initial void heavily contaminated), discarding urine, then collects next volume of urine = MSSU (mid-stream specimen of urine)
What are the bacteriostatic properties of urine
Low pH
High osmolality
High ammonia
Is the urinary tract sterile
Yes, except for terminal urethra
A MSSU culture – 10^5 is usually
An infection
MSSU culture – 10^3 10^4 is
Sometimes an infection is patient has symptoms
50% chance in no symptoms
MSSU culture – <10^3
usually no infection
What is a imitation of urine culture
• Some bacterial species are not normally present in terminal urethra/rectal flora and may be pathogenic at low colony numbers
Micro-organisms that cause UTIs
Gut flora- E.coli
Describe the route of infection for UTIs
Almost always ascending
What are the inflammatory responses in these organs: • Urethra – • Bladder – • Ureter – • Kidney – • Kidney – if recurrent/prolonged
UTI- predisposing Factors
- Urethra – urethritis
- Bladder – cystitis
- Ureter – ureteritis
- Kidney – acute pyelonephritis
- Kidney – if recurrent/prolonged infection chronic pyelonephritis
UTI- predisposing Factors
Name predisposing factors of UTIs
• 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
What are the consequences of obstruction at the level of the urethra
- Upper urethral and bladder dilatation
- Bilateral hydroureter
- Bladder dilatation, bilateral hydroureter and bilateral hydronephrosis chronic renal failure
What are the consequences of obstruction at level of renal pelvis at one side only
- Unilateral hydroureter
2. Unilateral hydroureter and unilateral hydronephrosis
What is the triad of obstruction
Infection–>Calculi–>Obstruction–>
Whats the most important example of obstruction in children
vesicoureteric reflux- due to decreased insertion angle of ureter
Common causes of obstruction in adults
- Men – Benign Prostatic Hyperplasia (not a tumour) of prostate – functional and anatomical obstruction
- Women – uterine prolapse
- Both sexes – tumours and calculi
How are females predisposition to have UTIs
Short urethra
Lack of prostatic bacteriostatic secretion
Closeness of urethral orifice to rectum
Sexual activity
Pregnancy- pressure on ureters and bladder
What are the complications of UTI
• 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
