Urinary tract infections
Description
- Symptomatic infection of the urinary tract - the diagnosis requires symptoms, not just a positive urine test
- *Asymptomatic bacteriuria (ASB) is common and is not UTI* - the central geriatric distinction, frequently mismanaged
Epidemiology
- ASB prevalence: ~20-50% of community-dwelling women >80, up to 50-100% in long-term care residents and catheterised patients
- One of the commonest reasons for (often inappropriate) antibiotic prescribing in aged care
- True symptomatic UTI incidence rises with age; F>M until very old age when prostatic disease narrows the gap
Aetiopathogenesis
- E. coli commonest organism; also Klebsiella, Proteus, Enterococcus; catheter-associated - broader range including Pseudomonas
- Risk factors: female anatomy, post-menopausal oestrogen deficiency, incomplete bladder emptying (prolapse, BPH, neurogenic bladder), catheterisation, diabetes, immobility, constipation
- Recurrent UTI - consider anatomical abnormality, incomplete emptying, post-coital factors, vaginal atrophy
Diagnosis
The core rule
- Diagnose UTI on localising urinary symptoms (dysuria, frequency, urgency, suprapubic pain, new/worsening incontinence, visible haematuria) plus a positive urine culture
- *A positive dipstick or culture WITHOUT urinary symptoms = asymptomatic bacteriuria - do not treat* (except pre-urological procedure or pregnancy, neither typical in this population)
The delirium/fall trap
- Delirium or a fall alone is NOT sufficient to diagnose UTI - both are common, non-specific, and usually reflect other causes when the only abnormality is bacteriuria
- Only attribute delirium to UTI if: new localising urinary symptoms, systemic signs (fever, rigors, haemodynamic change), or no other cause found after a full delirium screen
- Malodorous or cloudy urine, and pyuria alone, do NOT diagnose UTI in this population
Investigation
- Mid-stream urine for culture before starting antibiotics, in anyone with true symptoms
- Bladder scan for retention/incomplete emptying
- Blood cultures, FBE, UEC, CRP, lactate if systemically unwell (pyelonephritis/urosepsis)
- Imaging (renal tract ultrasound) if recurrent, pyelonephritis, or obstruction suspected
Management
A. Asymptomatic bacteriuria - do not treat
- Applies even with pyuria, indwelling catheter, or cognitive impairment
- Exceptions: pregnancy (rare in this population), planned invasive urological procedure
B. Uncomplicated cystitis
- Trimethoprim or nitrofurantoin (avoid nitrofurantoin if eGFR <30-45) first-line per Australian eTG; cefalexin an alternative
- Duration typically 5 days in older adults (shorter 3-day courses are for younger women)
- Avoid fluoroquinolones first-line (resistance, tendinopathy, QT, delirium risk)
C. Pyelonephritis / urosepsis
- IV empirical therapy per local antibiogram - typically gentamicin + amoxicillin, or a cephalosporin; escalate to broad-spectrum cover if septic shock or recent instrumentation/resistant organism risk
- Full sepsis pathway if systemically unwell (see Septicaemia/septic shock note)
- Source control - remove/change indwelling catheter if present and infected
D. Catheter-associated UTI
- Change or remove the catheter as part of treatment; treat only if symptomatic
- Avoid prophylactic antibiotics for catheter changes alone
E. Recurrent UTI prevention
- Vaginal (topical) oestrogen in post-menopausal women - reduces recurrence, minimal systemic absorption
- Optimise bladder emptying, treat constipation, adequate hydration
- Cranberry products - weak evidence, not routinely recommended
- Long-term prophylactic antibiotics only after non-pharmacological measures fail and specialist input
Associations
- Diabetes, incomplete bladder emptying, indwelling catheter
- Delirium (as a mimic/trigger when truly symptomatic - see Diagnosis for the distinction)
- Falls (indirect, via general unwellness if truly infected)
- Antimicrobial resistance from repeated inappropriate treatment of ASB
Natural history & complications
- Uncomplicated cystitis - resolves with appropriate short-course therapy
- Pyelonephritis/urosepsis - significant morbidity/mortality risk in frail older adults; can precipitate functional decline and delirium
- Over-treatment of ASB drives resistance and C. difficile risk without clinical benefit - the dominant harm in this population
- Recurrent true UTI - consider structural/functional urological review
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