Pathology of Urinary Tract Infection Flashcards
What is the common presentation of a UTI?
Dysuria (pain on micturition), frequency and smelly urine
Very young - unwell and failure to thrive
Ver old - incontinence and off their feet
What is renal blood flow equal to?
20-25% cardiac output
How does urine output change with oral intake of fluids?
Reabsorption of fluid is diminished if increased fluid intake which increases urine output
Does the ureters store urine?
No they do not store but have continuous trickle of urine
Explain the importance of the ureter entering the bladder at an angle
Increasing pressure from bladder as it fills - closes off ureter and stops the reflux of urine
What are some bacteriostatic properties of the normal urinary tract?
Free flow of urine in normal anatomy - assume enough fluids
Low pH, high osmolarity, and high ammonia content of urine
Prostatic secretions - Men
Antibacterial antibodies
Which part of the normal renal tract is not sterile?
Terminal urethra
Perineal skin and gut flora
What is a urinated specimen always contaminated with?
Terminal urethra flora
Explain a collection of urine after initial void
Patient voids and stops mid-stream, discarding urine, then collects next volume of urine - MSSU (mid-stream specimen of urine)
This has far less bacteria from terminal urethra but still present
Can there be a negative result in an MSSU?
No such thing as a negative result
How is an MSSU analysed?
Microbiology of culture under set conditions
Bacteria multiply in log phase growth
Can do a dip slide method - look at bacteria colonies
What value in MSSU culture usually means infections?
10^5 per ml
What is 10^3 to 10^4 per ml on MSSU culture?
Infection sometimes
Probable infection if there are symptoms
50% chance if no symptoms
What is less than 10^3 per ml on MSSU mean?
Usually no infection
What is a problem with interpretation of urine culture?
Some bacterial species are not normally present in the terminal urethra/ rectal flora and may be pathogenic at low colony numbers