Catheter-associated urinary tract infection (CAUTI)

Definition and the central rule. CAUTI is a symptomatic urinary infection in a patient with an indwelling urethral catheter, or within 48 hours of its removal. All patients with chronic indwelling catheters have bacteriuria, which is frequently polymicrobial and whose organisms change frequently — therefore bacteriuria alone is colonisation, not CAUTI.

Pathogenesis and risk factors. Duration of catheterisation is the single most important risk factor. Bacteria ascend extraluminally along the catheter–urethral interface or intraluminally after breaks in the drainage system, and form a protective biofilm that antibiotics cannot penetrate. Other risks: female sex, diabetes, poor catheter care, and catheter obstruction. Indwelling catheterisation is still overused in acute hospitals.

Accepted indications for an indwelling catheter (Kane). Urinary retention causing persistent overflow incontinence, symptomatic infection or renal dysfunction that cannot be corrected surgically/medically or managed by intermittent catheterisation; skin wounds or pressure ulcers being contaminated by urine; care of the terminally ill or severely impaired in whom bed and clothing changes are distressing; and patient preference when toileting causes excessive discomfort. Incontinence alone and staff convenience are not indications.

Presentation in the older adult. Often non-specific — fever without localising signs, new or worsening delirium, functional decline, falls, anorexia, suprapubic or flank pain, or new haematuria. The febrile response may be blunted or absent. Symptoms are non-specific, so other sources of infection must be carefully excluded before attributing them to the urinary tract.

Diagnosis. Do not perform surveillance cultures to guide management — all chronically catheterised patients are bacteriuric. Send urine culture only when symptomatic, and ideally from a freshly replaced catheter (biofilm on the old catheter gives misleading organisms). Pyuria does not diagnose CAUTI in a catheterised patient. Blood cultures if systemically unwell; ultrasound if obstruction, stones or abscess suspected.

Management and prevention — key principles of catheter care. Treat only if symptomatic; replace the catheter before starting antibiotics; give culture-directed therapy for the shortest effective duration. Prevention: maintain a sterile closed gravity-drainage system and avoid breaking it; secure the catheter to thigh or lower abdomen; wash the entry site with soap and water once daily only; do not routinely irrigate; do not use prophylactic or suppressive antiseptics or antimicrobials; treat bypassing without obstruction as bladder spasm; and remove the catheter at the earliest opportunity.

Practice has shifted to a bundled "avoid – remove – maintain" model: nurse-driven removal protocols, a documented daily catheter necessity review, and CAUTI as a mandatory device-associated HAI surveillance indicator. In India this is reinforced by the National Action Plan on Antimicrobial Resistance 2.0 (NAP-AMR 2.0, 2025– 2029, launched 18 November 2025), which makes infection prevention and control programmes mandatory in all healthcare facilities. Current IDSA/SHEA guidance continues to recommend against treating catheter-associated asymptomatic bacteriuria and against antibiotic prophylaxis at routine catheter change, and favours intermittent catheterisation or external (condom) catheters over indwelling catheters wherever feasible. If this appears as a 15-mark question, add: microbiology (E. coli, Klebsiella, Proteus — urease-splitting, struvite stones and encrustation; Pseudomonas, Enterococcus, Candida; rising carbapenem resistance in Indian ICUs); complications (bladder stones, periurethral abscess, epididymo-orchitis, prostatitis, bacteraemia, pyelonephritis, and squamous-cell bladder cancer with very long-term use); antibiotic duration (7 days if prompt response, 10–14 days if delayed response or bacteraemia); catheter material evidence (no clear benefit of silver-alloy or antibiotic-impregnated catheters); and a formal CAUTI prevention bundle with audit indicators.