Microbiology 6: Urinary Tract Infections Flashcards
What is the most common causative organism for UTI’s ?
E.coli
Name a virulence factor of some E.Coli serotypes that make them well adapted to cause UTIs ?
P-fimbriae
These allow the bacteria to adhere to the epithelium and therefore ascend
Which commensal skin bacteria is a rare cause of UTI but is more common in patients with Prosthesis e.g they have a long term in dwelling catheter ?
Staphylococcus epidermidis
Which 4 organisms are more common causes of UTIs in people with structural abnormalities ?
- Proteus mirabilis (kidney stones)
- Pseudomonas
- Klebsiella aerogenes (occur in abnormal urinary tracts - stones, neuro + anatomical abnormalities)
- Enterococcus faecalis
List 4 neurological causes of obstruction in the urinary tract ?
Poliomyelitis
Tabes dorsalis
Diabetic neuropathy
Spinal cord injury
Which organisms can cause a UTI which is negative for nitrites but positive for leucocytes on urine dipstick ?
- (Non coliform bacteria)
- Staphylococcus saphrophyticus
- Enterococcus faecalis
- Could also be urethral syndrome
List 3 ways you could collect a urine sample ?
Mid stream urine (MSU) - PREFERRED
Catheterisation
Supra Pubic aspiration
NB do the last 2 in certain situations to try and get a clean sample e.g. in young children
What is the most common causes of Sterile pyuria? (raised WCC but no growth on culture)
Other causes (5)
Prior treatment with antibiotics
Others:
- calculi: inflammation but not infection
- catheterisation
- bladder neoplasm
- TB - rare
- STD (chlamydia)
What colour is E.coli on chromogenic agar ?
Pink
What is the most common treatment for an uncomplicated UTI ?
Empirical treatment - Nitrofurantoin/Trimethoprim (3 days)
Although the resistance of E.coli is rapidly increasing so check with local governance.
Which infections occur in patients that have indwelling catheters ?
Candida
What is the most common treatment for Pyelonephritis ?
Co-amoxiclav +- gentamicin
Which organism that is not E.Coli tends to cause UTIs particularly in young women (2nd most common cause of UTI)?
Staphylococcus Saphrophyticus
Name a congenital abnormality that causes oligohydramnios and can cause Potter’s syndrome in male neonates?
Posterior urethral valve (PUV)
Give an example of a paediatric cause of Kidney scarring ?
Vesicoureteric reflux (VUR)
define uncomplicated UTI
infection is in a structurally and neurologically normal urinary tract - usually refers to lower UTI in women