Microbiology and Urinary tract

Question 1

How are UTIs classified?

Answer 1

Route of acquisition in the body
Site of infection
Route of transmission ( community acquired vs nosocomial)

Question 2

What are the routes of acquisiton of bacteria in UTI?

Answer 2

Ascending from urethra to bladder (in cystitis) or kidney (in pyelonephritis)
Haematogenous from blood to kidney (in pyelonephritis/renal abscess)

Question 3

What is renal abscess?

Answer 3

Pocket of pus formed in the kidney due to bacteria migration via ascending route from the urethra

Question 4

What is a nosocomial infection?

Answer 4

Infection transmitted while in hospital. UTI is the most nosocomial infection

Question 5

What is an upper UTI?

Answer 5

Pyelonephritis caused by ascending spread of bacteria from urethra to kidney

Question 6

What is a lower UTI?

Answer 6

Cystitis or urethritis. Cystitis is caused by ascending spread of bacteria from the urethra to the bladder.

Question 7

Cystitis

Answer 7

Inflammation of the bladder

Question 8

What is the epidemiology of UTI?

Answer 8

Greatest prevalence in elderly population, and in men enlarged prostate with reduced urinary flow increases risk.
Generally women due to anatomical sex differences. Peaks at pre-school age due to poor hygiene routines. and the elderly population

Question 9

Why are females at a higher risk for UTI?

Answer 9

Shorter urethra closer to perineum

Question 10

What is the bacterial cause of UTI?

Answer 10

Uropathogenic E.Coli
Mycobacterium tuberculosis

Question 11

What is Uropathogenic UTI?

Answer 11

Contains extra genetic material compared to commensal E.coli on pathogenicity-associated islands, coding for bacterial pathogenesis

Question 12

What are the virulence factors of Uropathogenic E.Coli?

Answer 12

Type 1 fimbriae for attachment to mannose residues on host cells for upper UTI, associated with cystitis causing strains.

Type P fimbriae to adhere to urinary tract cells

K antigen prevents phagocytosis

Question 14

What is the viral cause of UTI?

Answer 14

Adenovirus
BK and JC virus

Question 15

What is the BK and JC virus

Answer 15

Associated with infection and graft failure in kidney transplant.

Question 16

What is the parasitic cause of UTI?

Answer 16

Schistosoma hematobomium which resides in the bladder and causes inflammation, leading to cystitis

Question 17

How does adenovirus cause UTI?

Answer 17

Typically causes gastroenteritis but can lead to haemorrhagic cystitis (blood in urine)

Question 18

What increases risk of infection post-micrutition?

Answer 18

Urine remaining in

Question 19

What are the host defences against UTI?

Answer 19

Retrograde urine flow
Urine chemistry
Secreted factors
Mucosal defences

Question 20

What are the anti-microbial properties of urine chemistry?

Answer 20

Hypertonicity: causes water loss from microbe plasma membrane and leads to plasmolysis
Low pH
High urea concentration

Question 21

What is the antibody defence in UTI?

Answer 21

IgA

Question 22

What are the secretory factors against UTI?

Answer 22

IgA
Lactoferrin: milk derived protein which has high affinity for iron, a key element for organism growth.

Question 23

What are the mucosal defences against UTI?

Answer 23

Very few receptors in urinary tract for targeting by micro-organisms
Mucopolysaccharides such as glucoseoaminoglyca forming protective layer
Secretion of Tamms-Horsfall anti-adhesive protein for bacteria fimbraie

Question 24

What are the risk factors for UTI?

Answer 24

Female sex, catheterisation, Urinary tract surgery, pregnancy
Anatomical or congenital abnormality.

Question 25

What are the consequences of UTI in pregnancy?

Answer 25

Lower UTI increases risk of lower birth weight, premature delivery and perinatal morbidity. Risk of developing pyelonephritis.

Question 26

UTI in cystitis- presentation

Answer 26

Dysuria, urgency, suprapubic discomfort
Elderly-onset of confusion
Infants- poor feeding

Question 27

UTI in pyelonephritis- presentation

Answer 27

Loin pain, renal angle tenderness, fever and rigors