UTI infections Flashcards
classic symptoms of lower UTI?
dysuria, frequency and urgency
upper UTI aka + symptoms?
pyelonephritis
with loin pain/lower back pain, fever, rigors, hematuria
(renal angle tenderness)
what organisms normally cause a UTI?
Those derived from perineal flora
Gram negatives: ecoli (UPEC- uropathogenic) - most common!!!,
klebsiella, proteus
Gram positives: staphlococcus, (ie epidermidis, saprophyticus) enterococci
cause of UTI:
Introduction: sexual intercourse, catheterisation
Obstruction- causing stasis and therefore allows for replication: stones, enlarged prostate, tumours
what investigations might you do if you suspect a UTI?
and what results would you expect to see if diagnosis was correct?
MSU (mid stream urine sample)-
Dipstick: +leukocytes, +nitrites
Direct microscopy (neutrophils seen under film of urine)
Culture (CLED plate)
Bacteriuria defined as: (on colony count)
> 10^5 pure growth of bacteria per ml of urine
first line antibiotic to treat UTI?
Trimethoprim
what would you expect the urine to look like in UTI?
cloudy
In those with long term catheters, we would not bother doing direct microscopy on their urine or diagnose UTI based on dipstick leukocytes positive- why?
Because in those with long term catheters, after a few weeks 100% are colonised by bacteria, so these would definitely be positive anyway, even if they don’t have a UTI.
what is the point of the CLED plate?
especially grows bacteria which is common for urinary organisms
has pH indictor to tell if its lactose fermenting (yellow) - E.coli, staph
or non lactose fermenting (remains blue)
pseudomonas, proteus, shigella, salmonella
Why might you have problems identifying colonies if you use blood agar plate for urine?
because if proteus is present (even if non infective) it will swarm the plate, making anything else difficult to identify
pregnant women are asked to bring urine sample to the antenatal clinic- why?
because they might have an asymptomatic bacteriuria- which is fine to leave untreated in most people (i.e. lots of elderly have this, and we don’t treat)
but in pregnant women this needs to be treated even though asymptomatic or might cause miscarriage if it continues up the UT.
also to check for proteinuria - sign of pre-eclampsia
Multiple organisms were grown on the patients CLED plate- what might this indicate and what would you do?
suggests contamination
therefore get them to do MSU analysis again, advising particularly about washing hands before, and not collecting the first bit of the stream, so any non-causative bacteria would have been washed out first, to avoid contamination
