Urinary Tract Infection (lower)

Usually describes acute urethritis and cystitis caused by a microorganism.

Background/Epidemiology

• Common- accounts for around 1-3% of consultations in GP; affects around 3% of women at age 20 and increasing by ~1% every decade.
  • In men, UTI is uncommon except in neonates/infants and in men >60 with LUTS.

Risk

• More common in women because, the urethra is shorter and there is closer proximity between the urethra and the vagina and anus.
• Patients with catheters (or other instrumentation or foreign bodies- technically including renal stones) are also much higher risk
• Bladder outflow obstruction e.g. BPH, Prostate Cancer, urethral stricture
• Uterine prolapse
• Neurological conditions e.g. MS, diabetic neuropathy
• Diabetes mellitus
• NB Have a high clinical suspicion in elderly people (particularly females) who have acute onset fever or delirium of unknown cause, as this is the most common cause.

Pathophysiology

• The most common organisms to cause UTIs are
  • E coli (from the GI tract- account for ~75%)
  • Proteus spp
  • Staphylococcus saprophyticus
  • Other organisms include
    • Pseudomonas spp, streptococci and staph epidermidis
    • In hospital, Klebsiella and streptococci are more common (E coli still most common)
• Entry of the organisms may be retrograde (via the urethra), via the bloodstream (particularly in immunosuppressed) or direct (via instrumentation)

Clinical Presentation

• abrupt onset frequency and urgency of micturition
• scalding/burning pain (dysuria) in the urethra during micturition
• suprapubic pain during and after voiding
• feeling of incomplete emptying (due to spasm of the inflamed bladder wall)
• cloudy urine which may have an offensive smell
• there may also be haematuria
• Systemic symptoms e.g. fever, rigors, nausea/vomiting, confusion etc are usually only mild in simple UTI.  If these signs are present, suspect pyelonephritis and/or bacteraemia.
• Make sure to ask about previous UTIs and PMHx

Investigations

• NB UTI in females is a clinical diagnosis and investigations aren’t completely necessary.  UTI in males should be investigated with culture (male UTI is often immediately classed as complicated)
• Urinalysis
  • Leucocytes and nitrites are suggestive of UTI
• Urine microscopy/culture & sensitivity
• In some cases, particularly if the patient is having recurrent episodes or if there is a history suspicious of renal stones, USS imaging may be of benefit.

Management

• In uncatheterised patients
  • 1st line- Trimethoprim 200mg BD for 3 days (female- unless pregnancy is suspected/known) or 7 days (male) OR Nitrofurantoin MR 100mg BD or 50mg QDS for 3 or 7 days.
  • 2nd line- culture sample and treat as sensitivities

Special cases

• Patients with chronic kidney disease
  • In patients with CKD 3B/4/5, consider pivmecillinam (400mg stat then 200mg TDS for 3 days)
• UTI in pregnancy
  • 1st line nitrofurantoin MR 100mg BD or 50mg QDS for 7 days in the 1st and 2nd trimester
    • In the 3rd trimester, trimethoprim 200mg BD for 7 days
  • 2nd line cefalexin 500mg every 8 hours for a minimum of 7 days or as per sensitivities
• Recurrent UTIs in women (≥2/month or ≥3/year)
  • Treat for 6 months then review
  • 100mg trimethoprim at night/post-coital OR nitrofurantoin 50-100mg at night/post-coital
    • (Cranberry juice/extract also has evidence)
• Catheterised patients
  • In the presence of a catheter, antibiotics will NOT eradicate bacteria
  • Change catheter prior to treatment
  • Send sample
  • Treat only if symptomatic/systemically unwell
  • If in the community
    • Co-amoxiclav 625mg TDS for 14 days or cotrimoxazole 960mg BD for 14 days
      • 2nd line, base on sensitivities
  • If in hospital
    • IV Amoxicillin and Gentamicin (cotrimoxazole + gentamicin)
      • Aztreonam can be used as an alternative to gentamicin in patients with kidney failure (AKI/CKD)
      • Step down to co-trimoxazole or adjust as sensitivities suggest for 14 days total