UTIs

Question 1

Risk factors for UTIs + why

Answer 1

• 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

Question 2

What are coliforms?

Answer 2

Gram negative
Non sporeforming
Bacilli

Question 3

What is the most causative organism of UTIs?

Answer 3

Escherichia coli

Question 4

Types of UTI

Answer 4

• Cystis: bladder | lower UTI
• Pyelonephritis: kidneys |upper UTI

(Then complicated + uncomplicated)

Question 5

Virulence factors of E. coli

Answer 5

• flagellar: movement
• pili: attachment
• capsular polysaccharide: colonisation
• toxins: damages host membrane > renal damage

Question 6

What are the majority of UTIs caused by?

Answer 6

Coliforms
Mainly E. coli

Question 7

Presentation of cystitis | lower UTI

Answer 7

• Dysuria
• cloudy urine
• nocturia
• frequency
• urgency
• suprapubic tenderness
• possible renal angle tenderness
• haematuria
• mild pyrexia

Question 8

Presentation of pylonephritis |upper UTI

Answer 8

• high fever +/- rigours
• loin pain + tenderness
• renal angle tenderness
• nausea + vomiting
• +/- symptoms of cystitis
• haematuria

Question 9

Pathophysiology of UTI

Answer 9

• bacteria travels up the urethra
• into bladder (cystitis)
• can travel up ureters into kindey (pyelonephritis)

Question 10

Features of urinary system which prevent UTIs

Answer 10

• one way direction of urine flow
• emptying of bladder during micturition
• vesicouteral valves
• immunological factors
• mucosal barriers
• urine acidity

Question 11

Diagnosis of UTI

Answer 11

• history + presentation (mainly)
• Urine dipstick
• Visual inspection
• Urine culture (for complicated UTI)

Question 12

Prevalence of UTIs

Answer 12

• more common in women
• peak in women at:
  
  • preschool age
  • sexually active age
  • pregnancy age
• peak in men >60 years old

Question 13

When are urine dipsticks not useful for investigations of UTIs?

Answer 13

> 65 years old
Catheterised patients

Question 14

What is an uncomplicated UTI?

Answer 14

Infection by a usual organism (E. coli) in a patient with a normal urinary tract + normal urinary function

Question 15

What is a complicated UTI?

Answer 15

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

Question 16

When is a urine dipstick useful to investigate UTIs?

Answer 16

If a patient presents with at least 1 of:
- dysuria
- new nocturia
- cloudy urine

Question 17

Describe urine culture process
When is it used for investigation?

Answer 17

• 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

Question 18

General treatment of UTIs

Answer 18

• increase fluid intake
• regular analgesia
• address underlying disorder
• antibiotics (3 days for uncomplicated | 7 day for complicated)

Question 19

Antibiotic treatment of cystitis

Answer 19

• nitrofurantoin: 100mg twice a day
• trimethoprim: 200mg twice a day

3 days for uncomplicated
7 days for complicated (+men)

Question 20

When is imaging for used for UTIs?

Answer 20

• children
• septic patient to identify renal involvement

Question 21

Treatment of pyelonephritis

Answer 21

• 7-14 days oral antibiotics: cefalexin, co-amoxiclav
• use agent with systemic activity (not nitrofurantoin)
• IV antibiotics: ceftriaxone, gentamicin

Question 22

Antibiotics for treatment of pyelonephritis

Answer 22

Oral: cefalexin, co-amoxiclav
IV: ceftriaxone, gentamicin

Question 23

Treatment of UTIs in pregnancy

Answer 23

7 days abx
- cefalexin
- nitrofurantoin avoid in 3rd trimester
- amoxicillin only after sensitives are known

Question 24

Why should trimethoprim be avoided in preganncy?

Answer 24

it is a folate antagonists
folate is essential in early pregnancy especially in development of the CNs + neural tube defects

Question 25

Why should nitrofurantoin be avoided in 3rd trimester of pregnancy

Answer 25

risk of neonatal haemolysis

Question 26

Prevention of UTIs

Answer 26

• hydration
• promote good hygiene practice
• encourage post coital voiding
• avoid unnecessary catheterisation

Question 27

Urine dipstick results in UTI patient

Answer 27

Nitrite +
Leukocyte esterase +++
Possible haematuria

Question 28

What is the most likely causative organism of a UTI if urine dipstick shows negative nitrites + positive leukocyte esterase?

Answer 28

Staphylococcus saprophyticus

Question 29

Why does a UTI caused by E. coli show a positive nitrite in urine dipsticks?

Answer 29

E. coli converts nitrates to nitrites

Question 30

Why can a patient with a UTI have negative nitrites on dipstick?
What is the most common demographic affected by this?

Answer 30

• Patient is infected in staph saprophyticus which doesn’t convert nitrates to nitrites
• Girls who engage in sexual activity young