UTIs Flashcards
Risk factors for UTIs + why
- female: short urethra + closer proximity to anus
- pregnancy: enlarged uterus + hormonal effects of relaxation of musculature
- MS/stroke: affect bladder emptying > stagnant urine
- stones, enlarged prostate, retroperitoneal fibrosis: obstructive > stagnant urine
- abnormal renal tract
- diabetes mellitus/immunosuppression impaired host defence
- catheterised patients
What are coliforms?
Gram negative
Non sporeforming
Bacilli
What is the most causative organism of UTIs?
Escherichia coli
Types of UTI
- Cystis: bladder | lower UTI
- Pyelonephritis: kidneys |upper UTI
(Then complicated + uncomplicated)
Virulence factors of E. coli
- flagellar: movement
- pili: attachment
- capsular polysaccharide: colonisation
- toxins: damages host membrane > renal damage
What are the majority of UTIs caused by?
Coliforms
Mainly E. coli
Presentation of cystitis | lower UTI
- Dysuria
- cloudy urine
- nocturia
- frequency
- urgency
- suprapubic tenderness
- possible renal angle tenderness
- haematuria
- mild pyrexia
Presentation of pylonephritis |upper UTI
- high fever +/- rigours
- loin pain + tenderness
- renal angle tenderness
- nausea + vomiting
- +/- symptoms of cystitis
- haematuria
Pathophysiology of UTI
- bacteria travels up the urethra
- into bladder (cystitis)
- can travel up ureters into kindey (pyelonephritis)
Features of urinary system which prevent UTIs
- one way direction of urine flow
- emptying of bladder during micturition
- vesicouteral valves
- immunological factors
- mucosal barriers
- urine acidity
Diagnosis of UTI
- history + presentation (mainly)
- Urine dipstick
- Visual inspection
- Urine culture (for complicated UTI)
Prevalence of UTIs
- more common in women
- peak in women at:
- preschool age
- sexually active age
- pregnancy age
- peak in men >60 years old
When are urine dipsticks not useful for investigations of UTIs?
> 65 years old
Catheterised patients
What is an uncomplicated UTI?
Infection by a usual organism (E. coli) in a patient with a normal urinary tract + normal urinary function
What is a complicated UTI?
Patient has >1 factors that predispose to persistent infection, recurrent infection, or treatment failure
- abnormal urinary tract
- virulent organism Staph aureus
- immunosuppressed
- poorly controlled diabetes
- impaired renal function
- suspected pyelonephritis
UTIs in men are always complicated
When is a urine dipstick useful to investigate UTIs?
If a patient presents with at least 1 of:
- dysuria
- new nocturia
- cloudy urine
Describe urine culture process
When is it used for investigation?
- mid stream urine in adults
- clean catch in children
- culture urine within 4 hours of collection
- refrigerate or use boric acid preservative
. - used for complicated UTIs
General treatment of UTIs
- increase fluid intake
- regular analgesia
- address underlying disorder
- antibiotics (3 days for uncomplicated | 7 day for complicated)
Antibiotic treatment of cystitis
- nitrofurantoin: 100mg twice a day
- trimethoprim: 200mg twice a day
3 days for uncomplicated
7 days for complicated (+men)
When is imaging for used for UTIs?
- children
- septic patient to identify renal involvement
Treatment of pyelonephritis
- 7-14 days oral antibiotics: cefalexin, co-amoxiclav
- use agent with systemic activity (not nitrofurantoin)
- IV antibiotics: ceftriaxone, gentamicin
Antibiotics for treatment of pyelonephritis
Oral: cefalexin, co-amoxiclav
IV: ceftriaxone, gentamicin
Treatment of UTIs in pregnancy
7 days abx
- cefalexin
- nitrofurantoin avoid in 3rd trimester
- amoxicillin only after sensitives are known
Why should trimethoprim be avoided in preganncy?
it is a folate antagonists
folate is essential in early pregnancy especially in development of the CNs + neural tube defects
Why should nitrofurantoin be avoided in 3rd trimester of pregnancy
risk of neonatal haemolysis
Prevention of UTIs
- hydration
- promote good hygiene practice
- encourage post coital voiding
- avoid unnecessary catheterisation
Urine dipstick results in UTI patient
Nitrite +
Leukocyte esterase +++
Possible haematuria
What is the most likely causative organism of a UTI if urine dipstick shows negative nitrites + positive leukocyte esterase?
Staphylococcus saprophyticus
Why does a UTI caused by E. coli show a positive nitrite in urine dipsticks?
E. coli converts nitrates to nitrites
Why can a patient with a UTI have negative nitrites on dipstick?
What is the most common demographic affected by this?
- Patient is infected in staph saprophyticus which doesn’t convert nitrates to nitrites
- Girls who engage in sexual activity young
