UTIs

Question 1

Name the types of UTI

Answer 1

Lower UTIs:

• Urethritis
• Prostatitis
• Cystits

Upper UTIs:

• Pyelonephritis

Question 2

Which relationships between humans and microbes are relevant to UTIs?

Answer 2

• Colonisation
• Infection

Question 3

Why are females more prone to UTIs than males?

Answer 3

Shorter urethra and closer proximity to anus

Question 4

Why are UTIs particularly able to cause sepsis?

Answer 4

Often grem -ve bacteria with a bacterial wall containing endotoxin which is a strong stimulator of the immune response.

Can therefore stimulate sepsis and septic shock

Question 5

What are the host risk factors for UTIs?

Answer 5

Extremes of age : younger children & older adults (post-menopausal ♀)

Stress & starvation : not known to be a specific risk factor

Compromised barriers to infection :

• Physical (anatomical) :
  
  • Shorter ♀ urethra (especially if sexually active or post-menopausal)
  • Malformations (PKD, renal & ureteric malformations, strictures)
  • Internal obstructions (stones or tumours)
  • Bladder outflow obstruction (pregnancy, prostate enlargement)
  • Iatrogenic (urinary catheters, operations, post-operative changes)

Immunocompromised host : UTI more common with diabetes mellitus

Question 6

Describe the bacterial pathogenesis in UTIs

Answer 6

Access: Most bacteria causing UTIs are found in the colon

Adherence: pili (fimbrae) and adhesion molecules

Invasion: haemolysin increases invasive potential

Multiplication: colonisation of urinary tract may precede infection

Evasion: Relatively few immune cells in urinary tract

Resistance: Many bacteria causing UTIs have multi-drug resistance

Damage: Causes urethritis, cystitis, pyelonephritis, nephritis and septicaemia

Transmission: easily passed out in urine but low transmission risk

Question 7

Name some common UTI causing bacteria

Answer 7

• Escherichia coli = Gram -ve bacilli from colon
• Other “coliforms” (eg. Klebsiella, Enterobacter) = Gram -ve bacilli from colon
• Staphylococcus saprophyticus = Gram +ve cocci from perineum & vagina
• Enterococci spp. (faecal Streptococci) = Gram +ve cocci from colon
• Pseudomonas spp. = Gram -ve bacilli from the environment
• Tuberculosis = variably Gram-staining bacilli from systemic infection
• STIs (eg. Neisseria gonorrhoeae, Chlamydia spp.) → urethritis

Little correlation between organism and type of UTI

Question 8

In urine microscopy, what do casts indicate?

Answer 8

Renal disease

Question 9

In renal microscopy, what do WCC>100 indicate?

Answer 9

Infection

Question 10

In urine microscopy, what do RBCs indicate?

Answer 10

Haemorrhage or infection

Question 11

In urine microscopy what does the presence of epithelial cells indicate?

Answer 11

Contaminated sample

Question 12

In primary healthcare settings, which antibiotics are often used for UTIs?

Answer 12

Nitrofurantoin

Trimethoprim

Question 13

In secondary healthcare settings, what antibiotics are used for UTIs?

Answer 13

Coamoxiclav

Ciprofloxacin

Question 14

For suspected multi-drug resistance UTIs, which antibiotic is often used?

Answer 14

Ertapenem