UTI Flashcards
(42 cards)
How does normal flora differ along the urinary tract
Kidneys, bladder and prox urethra sterile
- distal urethra and external genital commensal flora
What is the risk of infection related to?
Host defences v bacterial virulence
Most common bacterial isolates in UTIs
- e.coli
- staph
- proteus, strep, klebsiella, enterococcus, others
Are dogs or cats more resistant to UTIs?
Cats
How do pathogens affecting horses and cattle differ to smallies?
Corynebacterium + similar species to smallies
What are cows particularly prone to?
Pyelonephritis (though this may be due to time of tx or assessment of cows cf. smallies)
Outline host defence mechanisms of the urinary tract
- normal micturition
- anatomical and physiological barriers
- mucosal defence barriers
- anti microbial effects of urine
- renal defence mechanism
How is normal micturition defined?
- voiding frequent, complete, with an adequate flow
Clinical conditionss resulting in voiding abnormalities -?
- urethral obstructions
- spinal disease
- bladder atony
- poor husbandry
Outline the protective anatomical and physiological factors
- urethral high pressure zone
- surface characteristics of urethral urothelium
- urethral peristalsis
- prostatic antibacterial fraction
- longer urethral length
- ureterovesical valves and ureteral peristalsis
Clinical conditions that may ^ risk of UTI?
- direct trauma eg. Catheterisation
- ectopic ureters
- urethral sphincter mechanism incontinence
- anatomical abnormalities following surgery eg. Perineal urethrostomy
What are some anti microbial properties of the mucosa?
> protective factors
- antibody
- surface GAGs
- intrinsic mucosal antimicrobial properties (waterproof etc.)
- bacterial interference
- exfoliation of cells
Clinical conditions that affect mucosal defence barriers and pdf UTIs
- trauma eg. Catheters
- disease processes eg. Neoplasia
- chemical irritants eg. Cyclophosphamide
Antimicrobial properties of urine
- extreme of pH (high or low)
- hyperosmolality
- high urea
- organic acids
Which clinical conditions affect urine PDF UTIs?
- older cats d/t poor concentration of urine
- dogs with DM glucosuria
Can anaerobes cause UTIs?
Not commonly
- so restricted range of feacal bacteria cause UTIs as majority are anaerobes
How do uropathogenic E. Coli over come host defences?
- avoid flushing action (S or P-fimbraie)
- complement resistant -> opsonoohagocytosis resistant
- haemolysin production and iron chelation abilities
- motility (some need to be able to move up urinary tract)
How does urine culture differ to normal culture?
- contaminants will give false positive if swab smeared on to agar
- sample must prevent bacterial growth in the urine (rapid transport to lab, hold at 4* c, add boric acid [bacteriostatic])
- 2ul onto blood and onto maconkey
- aerobic incubation, 18hrs
- look for >100,000 CFU/ml to demonstrate UTI (200 colonies from 2ul)
- less than this indicates contaminant
How does uropathogenic e.coli grow on agar?
Grows on blood, more on maconkey, is haemolytic
What is considered to be “no significant growth” ?
-
How does sensitivity testing differ in urine culture?
- higher drug levels than normal disks (because drugs concentrated in the urine)
How does recrudescence differ to recurrence?
Recrudescence or relapse (same strain, Tx failure)
Recurrence or reinfection (new strain, susceptibility of the animal)
> collect samples over several months from the same animal
PDF factors for cats and dogs developing UTIs?
- bitches more common
- older cats more common
- mostly bacterial (fungal rare, viral implicated as causal factor for FLUTD, incidence Unknown)
- parasitism possible 3rd world, not UK
Define UTI
Adherence, multiplication and persistence of an infectious agent in the urogenital system
