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
• poor hygiene
• vesico-ureteric reflux: urine reflux from bladder to ureters

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
• haematuria
• mild pyrexia
• confusion in older patients

Question 8

Presentation of pylonephritis |upper UTI

Answer 8

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

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

Investigations of UTI

Answer 11

• Urine dipstick
• MSU > microscopy, culture + sensitivities

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

Urine dipstick results in UTI patient

Answer 17

Nitrite +
Leukocyte esterase +++
Possible haematuria

Question 18

Describe urine culture process
When is it used for investigation?

Answer 18

• mid stream urine in adults
• clean catch in children
• culture urine within 4 hours of collection
• refrigerate or use boric acid preservative
  .
• used for pregnancy pts, recurrent UTIs, atypical symptoms, not improving with abx

Question 19

General treatment of UTIs

Answer 19

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

Question 20

Antibiotic treatment of cystitis

Answer 20

• nitrofurantoin: 100mg twice a day (avoid if eGFR <45)
• trimethoprim: 200mg twice a day

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

Question 21

When is imaging for used for UTIs?

Answer 21

• children
• septic patient to identify renal involvement

Question 22

Treatment of pyelonephritis

Answer 22

• 7-10 days oral antibiotics: cefalexin, co-amoxiclav
• use agent with systemic activity (not nitrofurantoin)
• IV antibiotics: ceftriaxone, gentamicin

Question 23

Antibiotics for treatment of pyelonephritis

Answer 23

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

Question 24

Complication of chronic pyelonephritis

Answer 24

recurrent infections > scarring of parenchyma > CKD > ESRD

Question 25

What can be used to assess for renal damage in recurrent pyelonephritis?

Answer 25

**dimercaptosuccinic acid scan** injecting radiolabeled DMSA which builds up in healthy kidney tissue

Question 26

Treatment of UTIs in pregnancy

Answer 26

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

Question 27

Why should trimethoprim be avoided in preganncy?

Answer 27

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

Question 28

Why should nitrofurantoin be avoided in 3rd trimester of pregnancy

Answer 28

risk of neonatal haemolysis

Question 29

Mechanism of action of trimethoprim

Answer 29

- folate antagonist - inhibits dihydrofolate reductase > inhibits tertahydrofolate production - which is needed for RNA, DNA + protein synthesis

Question 30

What drug should not be used at the same time as trimethoprim?

Answer 30

methotrexate also inhibits dihydrofolate reductase

Question 31

Adverse affects of trimethoprim

Answer 31

- myelosuppresion - rise in creatinine - tetratogenic

Question 32

Mechanism of action of nitrofurantoin

Answer 32

affects bacterial protein synthesis, DNA + RAN

Question 33

Prevention of UTIs

Answer 33

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

Question 34

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

Answer 34

Staphylococcus saprophyticus

Question 35

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

Answer 35

E. coli converts nitrates to nitrites

Question 36

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

Answer 36

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

Question 37

What is interstitial cystitis?

Answer 37

chronic condition causing bladder inflammation > lower UTI symptoms + suprapubic pain

Question 38

other names for Interstitial cystitis

Answer 38

bladder pain syndrome hypersensitive bladder syndrome

Question 39

Presentation of interstitial cystitis

Answer 39

- similar to lower UTI but more persistent >6 weeks - more common in women - suprapubic pain - worse with full bladder, relieved by emptying bladder - frequency - urgency

Question 40

Investigations +why of interstitial cystitis

Answer 40

- **urine dipstick** - UTIs - **swabs** - STIs - **cystoscopy** - bladder cancer - **DRE**: prostatitis, BPH, cancer

Question 41

findings of cystoscopy in interstitial cystitis

Answer 41

- **hunner lesions**: red inflamed patches on mucosa associated with small vessels - **granulations**: tiny haemorrhages on bladder wall

Question 42

conservative + medical management of interstitial cystitis

Answer 42

- lifestyle changes: smoking cessation, avoid caffeine and alcohol - bladder training - pelvic floor exercises - CBT - analgesia - antihistamines - anticholinergics *e.g. oxybutynin* - B3 receptor agonst *e.g. mirebegron* - intravesical medications *e.g. lidocaine, hyaluronic acid*

Question 43

Surgical management of interstitial cystitis

Answer 43

- cauterisation of hunner lesions during cystoscopy - botulinum toxin injection during cystoscopy - neuromodulation with implanted electrical nerve stimulator - ileocystoplasty - cystectomy

Question 44

what is ileocystoplasty?

Answer 44

augmentation of bladder, using section of ileum to increase capacity