UTIs - organisms, symptoms, diagnosis Flashcards
what is a lower UTI
infection confined to bladde (cystitis)
what is an upper UTI
infection involving ureters +/- kidneys (pyelonephritis)
what is a complicated UTI
systemic symptoms or urinary structural abnormalities eg stones
why are UTIs more common in women > men
women have shorter urethras, urethra closer to anus, sexual activity and pregnancy increase risk
which is the only part of the urinary tract that has commensal bacteria
lower end of urethra - kidneys, ureter and bladder sterile
what types of organisms are commonly found in the lower end of the urethra
coliforms and enterococci from bowel
what is the most common route of infection for UTI’s
ascending route where bacteria (gram -ive)from bowel comes into contact with urethra and ascends to the kidneys
what other way can UTI’s be caused (not ascending route)
blood stream –> kidneys –> multiple small abscesses (uncommon)
what is the most common causative organism of UTIs
E. coli
what other causative organisms are there
klebsiella, enterobacter, pseudomonas A, proteus
what gram stain is E. coli and what toxin can it release
gram -ive, endotoxin LPS
what can a proteus infection cause urine to smell like
foul smelling - burnt chocolate
how does proteus change the pH to cause stones
produces urease which breaks down urea –> ammonia –> increased pH (alkali) –> struvite (kidney) stones/ salts
what is seen on a proteus culture
gram -ive and ‘swarming’ - looks like a bulls eye and can cover whole agar plate
what type of bacteria is pseudomonas A
gram-ive bacillus (not a coliform)
which patients commonly get pseudomonas A UTIs
those with catheters
pseudomonas A is resistant to most antibiotics so which one is recommended for it and what class of AB is it
ciprofloxacin - quinolone
when is ciprofloxacin contraindicated
young children and pregnant women and causes C diff
what type of enterococcus can commonly cause UTI’s and what gram stain is it
enterococcus faecalis gram +ive
what type of staph can commonly cause UTI’s in women and what coagulase is it
staph saprophyticus, coagulase -ive
if staph A was found to be causing a UTI what would this indicate
bacteraemia and a spread from infection somewhere else in the body (is uncommon)
what are symptoms of a lower UTI
dysuria, increased frequency, increased urgency, suprapubic pain (no systemic signs)
what does sterile pyruia (pus in urine) indicate in a patient with lower UTI symptoms
chlamydia or gonorrhoea infection
what are symptoms of an upper UTI
fever, flank pain, N+V + lower UTI symptoms
who is more at risk of developing an upper UTI
females, young people, diabetics, pregnancy, catheterised patients
how do you correctly collect a urine specimen
wash perineum with sterile saline (often skipped), collect midstream urine (first pass urine contaminated with normal flora)
what is a suprapubic aspiration
aspiration directly from bladder, very invasive
what is a clean catch specimen and who would require it
urine sample assisted by physician eg for children or special needs
what is bag urine sample, when is it used and what would the results indicate
used on babies and is normally contaminated with bowel flora, negative culture rules our UTI, positive needs further investigations
what is the best transport and why medium for urine samples
boricon container - presevres bacteria from multiplying
if a sterile universal container is used what timeframe must it reach the lab by
within 2 hours
what might be seen on a dipstick that would indicate a UTI
leukocyte erserase (WBCs), nitrites, (RBC - does not always indicate infection diagnosis alone)
in which patients would a positive dipstick not always indicate a patient
catheter patients or elderly women as bacteriuria common - would need clinical diagnosis also
how is a diagnosis made in the lab
microscopy (not routine) , culture
