Urinary tract infection Flashcards
1
Q
Risk of UTI - facotrs
A
- host defences
- bacterial virulence
2
Q
How does an ascending infection start?
A
- colonisation of perineum and external genitalia
3
Q
What are the commonest bacterial isolates?
A
- E.coli > Staphs > Proteus > Klebsiella > Others
4
Q
Which spp are prone to UTI?
A
- cats more resistant to UTIs than dogs
- horses and cattle have similar bacteria spp but also get Corynebacterium
- cattle more prone to pyelonephritis
5
Q
List normal host defence mechanisms
A
- normal micturition
- anatomical and physiological factors
- mucosal defence barriers
- AM effects of urine
- renal defence mechanisms
6
Q
Describe normal voiding
A
- frequent
- complete
- adequate flow
7
Q
Causes - voiding abnormalities
A
- urethral obstruction
- spinal dz
- bladder atony
- poor husbandry
8
Q
Protective urinary physiology
A
- urethral high pressure zone
- surface characteristics of urethral urothelium
- urethral peristalsis
- prostatic antibacterial fraction (bacteriostatic)
- longer urethral length: males
- ureterovesical valves and ureteral peristalsis
9
Q
Conditions associated with increased UTI risk
A
- ectopic ureters
- urethral sphincter mechanism incompetence
- anatomical abnormalities following sx (e.g. perineal urethrostomy)
- urethral trauma (e.g. catherisation)
- disease (neoplasia)
- chemical irritants (cyclophosphamide)
- older cats (urine changes) > younger cats
- DM (glucosuria)
10
Q
Protective factors - mucosal barrier
A
- AB production
- surface GAG layer
- intrinsic mucosal AM properties
- bacterial interference
- cell exfoliation
11
Q
How is urine protective against UTI?
A
- extreme pH (low or high)
- hyperosmolality
- high (urea)
- organic acids
12
Q
Pathogenicity of bacteria causing UTI (UPEC)
A
- avoid flushing action of urine (P- and S-fimbriae)
- complement-resistant –> organophagocytosis-resistant
- haemolysin production and iron-chelating activity
- motility?
13
Q
Define UPEC
A
Uropathogenic E. coli
14
Q
Dx - UTI
A
- direct urine culture by swab is inappropriate (contaminants –> false positive, requires bacterial account)
- sample: rapid delivery, hold at 4 degrees, boric acid preservative
- blood agar and MacConkey
15
Q
How does a bacterial count show a UTI?
A
- > 100,000 CFU/ml = UTI
16
Q
Define recrudescence/ relapse
A
= same strain (indicating tx failure)
17
Q
Define recurrence or reinfection
A
= new strain (indicating susceptibility of the animal)
18
Q
Incidence of UTIs in cats/dogs
A
- variable, about 14% dogs get bacterial UTI during life
- bitches > dogs
- older > younger cats
- usually bacterial
- fungal rare
- viral implicated as causal factor in cats with FLUTD but incidence unknown
19
Q
Define UTI
A
= adherence, multiplication and persistence of an infectious agent in the uro(genital) system
20
Q
Define mircoburia
A
presence of microbes in urine
21
Q
Define bacturia
A
presence of bacteria in urina:
- INFECTION: >10^5/ml
- SUGGESTIVE OF INFECTION: >10^3 (depends on collection methods)
- CONTAMINATION:
22
Q
Define funguria
A
presence of fungi in urine
23
Q
Define pyuria
A
increased #s WBCs in urine (>5hpf)
- significance depends on method of collection
- cystocentesis >3-5/hpf
- catheter/free catch >5-10 /hpf
- increased WBCs indicate inflammation which may or may not be associated with infection
24
Q
What do CS depend on?
A
- predominant site (UUT vs LRT)
- presence of predisposing conditions (cacluli, DM, neoplasia)
25
CS - UUT (kidneys/ureters)
- renal/lumbar ain
- haematuria
- septicaemia
26
CS - LUT
- pollakiuria
- stranguria
- dysuria
- inappropriate urination
27
DX - UTI
- quantitative urine culture
| - other tests may suggest but not diagnose a UTI: urinalysis and urine sediment exam, gross appearance and smell
28
Outline urine sample collection
* best done aseptically to prevent contamination*
- cystocentesis best
- catheterised sample good alternative provided done carefully
- free catch not ideal
- culture (bladder biopsy or urolith) may be useful
- animal shouldn't have received ABs 5-7d prior to sample
29
Outline urine sample transport
- sealed sterilised container
- refridgerated
- send asap
- boric acid (bacteriostatic, sometimes used, may not be appropriate)
- follow courrier regulation
- avoid sending on friday
- remember costs and hidden costs
30
Tx principles - UTI
- ABs (mainstay)
- ideally based on C+S
- may be used empirically (first occurrence, pending results of C+S)
31
Principles - choosing an AB for UTI
- based on C+S
- bacteriocidal
- excreted in urine --> high concentrations
- no/low risk of toxicity
- easy to administer
- cheap
- good penetration into other related tissue if required (prostate)
- within cascade
- avoid abuse of new/BS ABs
32
Outline empiric AB use
- appropriate 1st incidence where no underlying cause
- short course (5-7d) of AB predicted to 'hit' the most likely bacteria (E.coli, Staph)
- drugs most appropriate (Ampicillin, potentiated amoxicillin, cefalexin, trimethoprim sulphonamide = TMS - latter now less popular)
- use top end of dose range
33
What to do if UTI signs recur after empiric AB tx?
urine sample + consider further investigation
34
Indications - therapeutic culture
- UTI associated with high risk morbidity/mortality (prostatitis, pyelonephritis, immunosuppression)
- toxic AB (gentamicin, amikacin)
- signs not improving after 3-5 d after starting tx
- before discontinuing ABs
35
Indications - surveillance culture
AFTER ABs GIVEN:
- ensure tx success
- if signs recur (same or different organism?)
- concerns about underlying condition which increases UTI risk (FLUTD, urinary incontinence, recessed vulva)
36
Causes - tx failure - UTI
- infection NOT the cause
- inadequate AB delivery (client factors, animal factors, ineffective drug/delivery)
- AB resistance (intrinsic, acquired)
- undiagnosed/untreated predisposing factors --> superinfection
37
Actions - poor clinical response to AB for UTI (but you are sure of infection)
# Define if culture -->
- no bacterial growth
- growth of same bacteria susceptible to current AB
- growth of same bacteria not susceptible to current AB
- culture of new spp
