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
adverse of ciprofloxacin used in pseudomonas?
c. diff
antibiotic of choice for coliforms
gentamicin IV (only given in hospital as IV and 3 days MAX
adverse of gentamicin
narrow therapeutic range (avoid in pregnancy). Risks renal toxicity and CNVII damage (deafness and balance)
choice of antibiotic for enterococci faecalis?
amoxicillin
if penicillin allergic then co-trimoxazole
risk in co-trimoxazole?
Steven-Johnson Syndrome
what is ESBL resistant to?
cephalosporins
penicillin
choice antibiotic for ESBL?
nitrofurantoin
when is nitrofurantoin active?
lower UTI as onlyreaches effective concentration once in bladder
resistance of CPE?
resistant to all antibiotics
what is CPE associated with?
UTI and travel to India is carbapenase-producing klebsiella
antibiotics for UTI in pregnancy?
amoxicillin (resistance high)
cefalexin (C. diff)
co-amoxiclav (c. diff)
antibiotic of choice for complicated UTI/ urosepsis?
gentamicin, but if renal function poor then temocillin
when are antibiotics given in catheter caused UTI?
only if symptomatic (unnecessary results in resistance)
describe abacterial cystitis/urethral syndrome
symptoms of UTI with pus cells in urine but no growth on culture
causes of abacterial cystitis/urethral syndrome
early phase UTI
urethral trauma
chlamydia/gonorrhoea
management of abacterial cystitis/urethral syndrome
alkalinise urine for symptomatic relief
describe asymptomatic bacteriuria
significant bacteruria but patient is asymptomatic
are antibiotics required in asymptomatic bacteriuria
no, unless pregnancy as there is risk of pyelonephritis, IUGR or premature labour
