9. UTIs

Question 1

What factors play a role in the pathogenesis of a UTI?

Answer 1

Innoculum size
Virulence of organism
Host factors
Tract abnormalities
Age

Question 2

What host factors can predispose to a UTI?

Answer 2

Incomplete bladder emptying
Low water intake
Integrity of the vesicle-uretal valve
Length of the ureter
Lactobacillus is protective in young women

Question 3

What tract abnormalities can predispose to UTI?

Answer 3

Obstruction eg. stones, malignancy, prostate
Vesico-ureteric reflux
Neuropathic bladder (diabetics)
Foreign bodies

Question 4

How does age predispose to UTIs?

Answer 4

Prostatic enlargement
Lose the bactericidal function of prostatic fluid
Weak pelvic floor muscles in women cause the uterus to press on the bladder

Question 5

What are the routes an organism can take to cause a UTI?

Answer 5

Ascending
Haematogenous
Direct (ie. fistulas)

Question 6

What is the most common UTI-causing pathogen?

Answer 6

E.coli

Question 7

What pathogen is associated with stone formation?

Answer 7

Proteus

Urease promotes stone formation

Question 8

Which pathogens are opportunistic?

Answer 8

Enterococci

Pseudomonas

Question 9

Which pathogens are associated with HCAIs?

Answer 9

Enterobacterales
Pseudomonas
Enterococcus faecalis

Question 10

What is needed to diagnose a UTI?

Answer 10

Clinical symptoms with supporting evidence

ie. bacturia isn’t the same as a UTI

Question 11

What cases should bacturia be treated?

Answer 11

Pregnancy

If urinary tract has been manipulated

Question 12

What specimens can be used in the investigation of a UTI?

Answer 12

Midstream urine
Catheter specimen urine
Nephrostomy or ileal conduit
Blood if systemically unwell

Question 13

What investigations are done to confirm UTI?

Answer 13

Dipstick
Microscopy, culture and sensitivity of specimen
- >10 pus cells
- >10^5 colonies on chromogenic agar

Question 14

What do colony sizes less than 10^5 mean?

Answer 14

10^4 needs clinical judgement

10^3 means sample was probably contaminated

Question 15

What is the use of dipsticks in UTIs?

Answer 15

Useful to rule out UTIs: if negative for nitrites and leucocytes then very unlikely

Question 16

What is the treatment length for

a) female cystitis
b) male cystitis
c) pyelonephritis

Answer 16

a) 3 days
b) 7 days
c) 7-14 days

Question 17

Why is asymptomatic bacturia treated in pregnancy?

Answer 17

Can become pyelonephritis which can increase the risk of miscarriage and prem birth

Question 18

Why is the risk of UTI increased in pregnancy?

Answer 18

Smaller bladder size
Hormones reduce the tone of the urethral muscle
Stasis due to pressure from uterus

Question 19

What imaging is used for follow up care of UTIs in children?

Answer 19

Ultrasound to show structural abnormalities
DMSA scan to show renal parenchymal defects after infection
Micturating cystourethrogram to show reflux

Question 20

Why is there an increased risk of UTIs in diabetics?

Answer 20

Neuropathy causes bladder dysfunction

Glucosuria is a good medium for bacteria

Question 21

What is the treatment of acute pyelonephritis?

Answer 21

Cefuroxime and gentamicin

Question 22

What is sterile pyuria?

Answer 22

WBCs in urine but nothing on culture

Question 23

What are the causes of sterile pyuria

Answer 23

Antibiotics
Tumours, stones
Chlamydia and other STIs
TB and brucellosis

Question 24

Which pathogen most commonly spreads haematogenously to the kidneys?

Answer 24

TB