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
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
Pseudomonas
Klebsiella aerogenes
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)
Catheterisation
Supra Pubic aspiration
What is the most common causes of Sterile pyuria? (raised WCC but no growth on culture)
Prior treatment with antibiotics
What colour is E.coli on chromogenic agar ?
Pink
What is thew 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?
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 neuroogically normal urinary tract
define complicated UTI
infection in a urinary tract with functional or structural abnormalities (including indwelling catheters and calculi
men, pregnant, children,
what is staphylococcus saorophyticus
coagulase negative
associated with infections in young women
P fimbrae allows adherence to the epithelium
what infections are common in the presence of structural abnormalities (UTIs)
proteus pseudomonas klebsiella enterobacter enterococci staphlococci
how can reflux cause UTIs
vesicoureteric reflux
residual pool of urine in the bladder after urination
can cause kidney scarring
symptoms of UTI in nonates and children <2 yrs
non specific
failure to thrive
vomiting
fever
symptoms of UTI in children >2
frequency
dysuria
abdominal or flank pain
what do the following of urine culture suggest:
- white cells pyuria
- squamous epithelial cells
white cells pyuria - infection
squamous epithelilal cells - contaminations
how many single organisms must be cultures to diagnose UTI
> 10^5 CFU/mL with urinary symptoms
different colours on chromogenic agar
pink = E.Coli
blue = other coliforms
light blue = gram positives
which antibiotics are used to treat UTI
nitrofurantoin - EGFR must be >45ml/min
trimethoprim - if low risk of resistance
pregnant/ breastfeeding = cefalexin, co-amoxiclav (2nd line)
male = cefalexin, ciprofloxacin
pyelonephritis = co-amoxiclav +- gentamicin
