Catheter-Associated UTI
Urinary tract infection occurring in a patient with an indwelling urethral catheter, usually due to biofilm-associated uropathogens. Diagnosis and management differ from uncomplicated cystitis; removal of the catheter where possible is central to treatment.
Key Facts
Key points
- Definition: significant bacteriuria (often ≥10⁵ CFU/mL) plus symptoms/signs of UTI in a patient with a urethral catheter (or within 48 hours of removal).
- Common organisms: Escherichia coli, Klebsiella spp., Enterococcus spp., Pseudomonas aeruginosa; consider multidrug resistance in healthcare-associated cases.
- Do not treat asymptomatic bacteriuria except in pregnancy or before invasive urological procedures (per local policy).
- First-line antibiotics (when treatment indicated): guided by culture; common choices include nitrofurantoin (only if eGFR ≥45 mL/min/1.73 m² and no catheter obstruction), trimethoprim, or a cephalosporin — adjust per sensitivity and severity.
- Catheter management: remove if possible; if needed, change catheter at treatment onset; avoid silver-coated catheters for routine infection prevention.
- Duration: typically 7 days if prompt response; longer courses if slow response or severe sepsis (follow local stewardship guidance).
Overview
Definition and epidemiology
Catheter-associated urinary tract infection (CAUTI) is one of the commonest healthcare-associated infections. Indwelling urethral catheters breach normal urinary defence mechanisms and allow biofilm formation on the catheter surface.
Pathophysiology
Biofilms harbour bacteria that are relatively protected from antibiotics and host immunity. Catheter blockage, inadequate closed-drainage systems, and breaches in aseptic technique increase risk.
Prevention (UK practice)
- Use catheters only when clearly indicated; review need daily.
- Maintain closed drainage; avoid unnecessary irrigation.
- Hand hygiene and aseptic insertion by trained staff.
- Consider alternatives (intermittent catheterisation, condom drainage) where appropriate.
Clinical Presentation
Symptoms and signs
- New or worsening suprapubic pain, loin pain, rigors, fever, confusion (especially older adults), hypotension (sepsis).
- Catheter-related symptoms may be subtle; hypothermia or delirium may be the only clue.
Examination
- Fever, tachycardia, suprapubic tenderness; assess for acute kidney injury and septic shock.
Red flags
- Sepsis (NEWS2 escalation), anuria, refractory hypotension, concern for obstructive uropathy (requires urgent urology input).
Differential Diagnosis
| Diagnosis | Clues | Notes |
|---|---|---|
| Asymptomatic bacteriuria | No systemic/local symptoms | Do not treat except specific indications |
| Non-infective catheter irritation | Dysuria without fever | Review catheter need |
| Clostridioides difficile colitis | Diarrhoea, toxins | Concurrent antibiotic exposure |
| Acute pyelonephritis without catheter | Similar presentation | Catheter still increases complexity |
| Prostatitis/epididymo-orchitis | Local examination findings | Consider if catheter recently removed |
| Other sources of sepsis | Alternative focus | Parallel assessment (chest, line, abdomen) |
Diagnosis / Investigation
Bedside
- NEWS2, urine dipstick (limited specificity with catheters), urine microscopy if available.
- Urine culture from a freshly placed catheter or after catheter change (avoid sampling from drainage bags).
Bloods
- FBC, CRP, U&Es, LFTs, blood cultures if systemic features.
Imaging
- Renal tract ultrasound if obstruction suspected (hydronephrosis).
- CT KUB if calculus/abscess suspected.
Microbiology
- Culture identifies organism and resistance; check prior isolates.
Management
Immediate care
- Sepsis 6 if septic: oxygen, IV access, fluids, lactate, antibiotics, urine output monitoring.
- Analgesia and antipyretics as needed.
Catheter strategy
- Remove if no longer needed; if retention risk, replace at start of therapy.
- Do not routinely irrigate unless obstruction.
Antibiotics (examples — follow local formulary and culture)
Oral (mild, outpatient where appropriate):
- Nitrofurantoin 50–100 mg QDS for 7 days (avoid if eGFR <45; not for upper tract sepsis as sole agent if concern).
- Trimethoprim 200 mg BD for 7 days if sensitive.
- Pivmecillinam 400 mg TDS (where available) per sensitivity.
IV (inpatient/severe):
- Co-amoxiclav 1.2 g TDS (if non-severe and susceptible).
- Ceftriaxone 1–2 g OD (adjust renal/hepatic impairment).
- Piperacillin/tazobactam 4.5 g TDS if Gram-negative resistance risk.
- Meropenem 1 g TDS only when MDR risk and specialist advice.
Duration: commonly 7 days if improving; extend if bacteraemia/abscess.
Escalation
- ICU if persistent shock; urology for obstruction/stone.
Prognosis
With prompt catheter management and appropriate antibiotics, most patients improve within 48–72 hours. Bacteraemia and obstructive uropathy worsen prognosis. Recurrence is common if catheters remain in situ unnecessarily.
Other Relevant Information
Stewardship pearls
- Treat symptoms + culture, not colonisation.
- Document indication and removal plan for every catheter.
- Avoid prophylactic antibiotics solely to prolong catheter use.