S9.2 Urinary Tract Infections

Question 1

List some host causes of UTIs

Answer 1

Shorter urethra - more infections in females
Obstruction of urethra - enlarged prostate, pregnancy, stones, tumours
Neurological problems - incomplete emptying, residual urine
Ureteric reflux - ascending infection from bladder (backflow of urine into ureters) especially in children
Double ureter - in children

Question 2

Name some sites and causes of urinary tract obstruction

Answer 2

PUJ, ureter, VUJ - calculi
Bladder neck - hypertrophy
Prostate - BPH
Urethra - stricture

Question 3

Which bacteria most commonly causes UTIs?

Answer 3

Most caused by coliforms, E. coli being the main one

Question 4

Describe what leukocyte and nitrite results would appear on a dipstick for different bacteria in UTI

Answer 4

E. Coli: leucocytes + nitrates +
Staphylococcus epidermis: leucocyte + nitrates -
Staphylococcus saprophyticus (common in young women or hospitalised patients): leucocytes + nitrates -

Question 5

Describe some virulence factors of bacteria in UTIs

Answer 5

Fimbriae allow attachment
Haemolysins damages host membranes
K antigen produces polysaccharide capsule making it harder for white cells to destroy
Urease breaks down urea, creating favourable environment for bacterial growth

Question 6

Describe an upper UTI

Answer 6

Pyelonephritis

Get fever and loin pain

Question 7

Describe a lower UTI

Answer 7

Cystitis

Get dysuria and bladder infection

Question 8

Describe an uncomplicated UTI

Answer 8

Infection by a usual organism in a patient with a normal urinary tract and function.

Question 9

Describe a complicated UTI

Answer 9

When factors predispose patient to recurrent infection or treatment failure:

Abnormal urinary tract e.g. vesicoureteric reflux
Virulent organism e.g. S. aureus
Impaired renal function, or host defences e.g. DM

Question 10

How are UTIs investigated?

Answer 10

Turbidity - visual urine inspection
Dipstick - look for leucocytes, nitrates (NB not useful in uncomplicated UTI)
Culture - used in complicated UTI
Imagining - look for ureteric reflux

Question 11

What is sterile pyuria?

Answer 11

Urine with WBCs but appears sterile by standard culturing.

Due to antibiotics, urethritis

Question 12

What is asymptomatic bacteruria?

Answer 12

Bacteria in urine with no symptoms.

Question 13

How are uncomplicated UTIs treated?

Answer 13

3 days trimethoprim

Question 14

How are complicated UTIs treated?

Answer 14

5-7 days trimethoprim

Question 15

How is pyelonephritis treated?

Answer 15

14 days co-amoxiclav