Microbiology Flashcards
define UTI
presence of microorganisms in urinary tract causing infection
where is a lower UTI confined to?
bladder (cystitis)
where is a upper UTI present?
ureters +/- kidneys (pyelonephritis)
what is the only area of the urinary tract that is not sterile?
the lower end of the urethra which is colonised by bacteria (enterococci and coliforms from large bowel)
what is different about a complicated UTI?
systemic symptoms
urinary structural abnormality/ stones
risk factors for UTI
- female (short, wide urethra and proximity of urethra to anus)
- sexual activity (females)
- pregnancy
- catheter
- abnormalities of urinary tract
routes of infection for UTI?
ascending (from bowel)
bloodstream
causative gram negative organisms
coliforms (E. coli, klebsiella, enterobacter)
proteus
psuedomonas
what indicates a proteus caused UTI?
foul smelling
renal calculi
what indicates a pseudomonas caused UTI?
associated with catheters and instrumentation
how to manage pseudomonas UTI
ciprofloxacin
gram positive causative organisms
enterococcus (faecalis and faecium)
staph saphrophyticus (coagulase negative staph)
staph aureus
indication of enterococcus UTI
hospital acquired infection
what increases risk of staph saphrophyticus infection?
women of child-bearing age
what causes staph aureus UTI?
usually only in bacteraemia
presentation of UTI
dysuria
frequency, nocturia
haematuria
fever, loin pain and rigors suggest upper urinary tract
diagnosis of UTI
- mid-stream sample
- urine sample
- microscopy (urgent only)
- Culture (Kass’s criteria)
how can you transport MSU sample?
boricon container (contains boricon acids so stops bacteria multiplying for 24 hours) sterile universal container (must reach lab within 2 hours)
other urine sample collection methods
- clean catch urine (done by nurse in urine or disabled)
- bag urine (babies- negative useful)
- catheter specimen
- suprapubic aspiration
who’s urine do you NOT dipstick?
elderly
catheterised patients
dipstick results?
leukocyte esterase (WBC)
nitrites (bacteria reduce nitrates)
protein and blood
microscopy of urine
looks for pus cells (only done in urgent cases)
Kass’s criteria for urine culture
> 10^5 organisms/ml = probable UTI (mixed growth not significant)
10^4 organisms/ml = repeat specimen
<10^3 organisms/ml= not significant
who does Kass’s criteria apply to?
women of child-bearing age
