Urinary tract infections

Question 1

What parts of the urinary tract are sterile in normal health?

Answer 1

Kidneys

Ureters

Bladder (usually, but my not always be the case)

Question 2

What type of flora does the urethra contain?

Answer 2

Perineal flora

Skin/lower GI tract flora

Question 3

What does skin flora consist of?

Answer 3

Predominantly coagulase-negative staphylococci

Question 4

What does perianal flora consist of?

Answer 4

Skin flora

Lower GI tract flora

• Anaerobic bacteria
• Aerobic bacteria
• -Enterobacteriaceae (“enteric Gram-negative bacilli”, “coliforms”)
• Gram-positive cocci
• -Enterococcus spp.

Question 5

What is cystitis?

Answer 5

Lower urinary tract infection syndrome

• Dysuria
• Urinary frequency
• Urgency
• Supra-pubic pain/tenderness
• Polyuria, nocturia, haematuria

Question 6

What is pyelonephritis?

Answer 6

Upper urinary tract infection

- Infection of kidney and/or renal pelvis

Question 7

What is the clinical presentation of pyelonephritis?

Answer 7

Symptoms of lower UTI

Loin/abdominal pain/tenderness

Fever

Other evidence of systemic infection

• Rigors, nausea, vomiting, diarrhoea
• Elevated CRP, WBC

Question 8

What is ‘urethral syndrome’?

Answer 8

Controversial term

a.k.a. abacterial cystitis, frequency-dysuria syndrome

Mostly affects 30-50 yr old women

Symptoms of lower UTI without demonstrable infection

Question 9

What criteria is used to define ‘significant bacteriuria’?

Answer 9

Kass criteria = 10^5 cfu/mL = “significant bacteriuria”

Question 10

What are the limitations of the Kass criteria?

Answer 10

Bacterial count is on a normal curve

Many symptomatic females have bacterial counts of less

Question 11

What is asymtomatic bacteriuria?

Answer 11

Significant bacteriuria
- With a single organism

No symptoms of urinary tract infection

Question 12

What is sterile pyuria?

Answer 12

Pus cells in urine

No organisms grown

Question 13

What are the risk factors for UTI?

Answer 13

Female sex - 10:1 female:male ratio

Urinary stasis - Pregnancy, prostatic hypertrophy, stones, strictures, neoplasia, residual urine

Instrumentation

Sexual intercourse - Associated with recent sexual intercourse and commoner in sexually active women

Fistulae - Recto-vesical, vesico-vaginal

Congenital abnormalities - Vesico-ureteric reflux (VUR)

Question 14

What are the sources of infection in UTIs?

Answer 14

Perineum
- Movement of bacteria along a lumen

Fistulae
- Movement of bacteria from genital/GI tract to urinary tract

Haematogenous
- Seeding of infection from the blood (rare)

Question 15

Which organisms commonly cause UTIs?

Answer 15

E. coli
S. saprophyticus
P.mirabilis
Enterococcus spp.
Klebsiella spp.
Other coliforms
P. aeruginosa

Question 16

Which organism causes 70-80% of all GP UTIs and 50% of all hospital UTIs?

Answer 16

E.coli

Question 17

What are the possible causes of sterile pyuria?

Answer 17

Inhibition of bacterial growth

• Unprescribed antibiotics
• Specimen contaminated with antiseptic

“Fastidious” (hard to grow) organisms

• e.g. Mycobacterium tuberculosis, Haemophilus spp., Neisseria gonorrhoeae
• Anaerobes

Urinary tract inflammation

• Renal or bladder stones
• Other renal disease

Question 18

How do long-term indwelling catheters result in bacteriuria?

Answer 18

Biofilm colonisation (NB: colonisation does not equal infection)

Question 19

At LTHT under what circumstances may antibiotic prophylaxis be used?

Answer 19

History of symptomatic urinary catheter-associated infection with previous catheter changes

Purulent urethral/suprapubic catheter exit site discharge

Catheter or meatal/suprapubic catheter exit site colonisation with Staphylococcus aureus (including MRSA).

Question 20

What samples are taken for microbiological testing if a UTI is suspected?

Answer 20

Urine

• Mid-stream (MSU)
• Catheter urine (CSU)
• “Clean catch”
• Supra-pubic aspirate (SPA)

Blood
- Suspected pyelonephritis

• Microscopy, culture and sensitivity testing

Question 21

Why would you perform an early morning urine (EMUx3) test?

Answer 21

For suspected urinary tuberculosis

Question 22

What are the indications for further investigation?

Answer 22

Recurrent UTI

Any UTI in male patient

Any UTI in childhood

Pyelonephritis

Question 23

What further investigations may be carried out?

Answer 23

Renal tract ultrasound scan

Specialised tests

• Isotope scans (DMSA, DTPA, MAG3)
• micturating cystourethrogram

Question 24

What are the requirements for a UTI antibiotic?

Answer 24

Present in urine

Minimally toxic

Effective against likely organisms

Easily administered

Cheap

Question 25

Give examples of some common UTI antibiotics?

Answer 25

• Nitrofurantoin
• Pivmecillinam
• Trimethoprim
• Fosfomycin

Question 26

What is the treatment for cystitis in females?

Answer 26

Treatment pre-empts microbiology results

Short course of antibiotics - 3-days

Question 27

What is the treatment for cystitis in males (or the recurrence of symptoms)?

Answer 27

• Longer course (7 days)

Question 28

What is the treatment for pyelonephritis?

Answer 28

Empiric therapy

• Cefuroxime, ciprofloxacin
• Piperacillin-tazobactam (if >65 yrs old)

Targeted therapy
- Based on sensitivity results

Duration
- 7-14 days depending on antibiotic used

Question 29

What is the treatment for asymtomatic bacteriuria?

Answer 29

Treat only specific groups:

• Pregnant
• • Association with upper UTI, pre-term delivery, and low birth weight babies
• Infant
• • Prevention of pyelonephritis and renal damage
• Prior to urological procedures
• • Prevention of UTI/bacteraemia

Elderly, catheterised etc. do not require antibiotics