Catheter-related Urinary Tract Infection

Catheter-associated urinary tract infection (CAUTI) occurs in the presence of an indwelling urinary catheter, with risk rising with duration of catheterization (roughly 3 to 8% risk per day of catheterization). Distinguishing true infection from catheter-associated asymptomatic bacteriuria (extremely common, present in the majority of long-term catheterized patients, and not requiring treatment) is the central and most important clinical task, given that overtreatment of asymptomatic bacteriuria is a major driver of unnecessary antibiotic use and resistance in this population.

A diagnosis of CAUTI requires both a positive urine culture AND symptoms attributable to the urinary tract (fever, new flank pain, altered mental status without another identified cause in a catheterized patient, or, in a patient without cognitive impairment or spinal cord injury who can report symptoms, suprapubic discomfort or new hematuria), rather than culture positivity alone. Cloudy or malodorous urine alone, in the absence of the above features, does not indicate infection and is not an indication for testing or treatment.

Urine culture from a freshly obtained catheter sample (via the sampling port after cleaning, not from the drainage bag, which reflects colonization of the tubing rather than the bladder), sent only in the presence of compatible symptoms as above
Routine screening urine culture in an asymptomatic catheterized patient is not recommended, and a positive result in this context (asymptomatic bacteriuria) should not be treated except in specific circumstances (pregnancy, or before a urological procedure with expected mucosal bleeding)
Blood cultures if systemic sepsis is present

Remove or replace the catheter if it has been in place for more than 7 days at the time of CAUTI diagnosis, given evidence this improves clinical response, alongside reassessing whether continued catheterization is genuinely necessary at all
Empirical antibiotics, guided by local resistance patterns given catheter-associated infections are more likely to involve resistant organisms than uncomplicated community UTI: options include ciprofloxacin, or, for more severe presentations or where resistant organisms are more likely (recent hospitalization, prior antibiotic exposure), piperacillin-tazobactam or a carbapenem, rationalized once culture and sensitivity results are available
Treatment duration is typically 7 days for prompt responders, extended to 10 to 14 days for delayed response or more severe presentations
Asymptomatic bacteriuria in a catheterized patient is not treated, with the sole common exceptions being pregnancy or planned urological instrumentation with expected mucosal trauma
Prevention (the most impactful intervention overall given how common CAUTI is): avoid unnecessary catheterization, use the shortest duration possible, maintain a closed drainage system, and consider intermittent catheterization as an alternative to a long-term indwelling catheter where clinically appropriate

Referral: urology for recurrent CAUTI, catheter-related complications (blockage, stone formation), or where long-term catheter necessity should be reassessed.

Clinical toolsCalculators

BMI GCS EDD Parkland Formula

Corrected Sodium Corrected Calcium Anion Gap Creatinine Clearance Insulin Calculations qSOFA Wells PE Wells DVT CHA₂DS₂-VASc HAS-BLED CURB-65 Centor/McIsaac

Urinary Tract Infection

Also known as: UTI

Bacterial infection of the urinary tract: lower UTI/cystitis (bladder) or upper UTI/pyelonephritis (kidney, more severe).

Predominantly E. coli (~80%), also Klebsiella, Proteus, Enterococcus, Staph saprophyticus (young sexually active women).

Classified: uncomplicated (healthy non-pregnant women, normal urinary tract) vs. complicated (male, pregnant, catheter, structural/functional abnormality, immunocompromised, recent instrumentation).

Cystitis: dysuria, frequency, urgency, suprapubic pain, hematuria: no fever/flank pain/systemic symptoms
Pyelonephritis: fever, rigors, flank/loin pain, costovertebral angle tenderness, nausea/vomiting, plus lower UTI symptoms often present; can progress to sepsis (see Sepsis entry)
Elderly: may present atypically: confusion, falls, functional decline, without classic urinary symptoms
Catheter-associated: often asymptomatic bacteriuria (do NOT treat unless symptomatic) vs. true infection (fever, new flank pain, altered mental status without other cause)

Uncomplicated cystitis in women with classic symptoms: clinical diagnosis sufficient, treat empirically without culture
Urine dipstick: nitrites (specific) and leukocyte esterase (sensitive) — supportive, not required if classic symptoms present
Urine culture: indicated for pyelonephritis, complicated UTI, treatment failure, recurrent UTI, pregnancy, men, catheterized patients — guides targeted therapy
Bloods (FBC, U&E, CRP, blood cultures): if systemically unwell/pyelonephritis/suspected sepsis
Imaging (renal ultrasound/CT): recurrent pyelonephritis, suspected obstruction/stone, failure to respond to treatment, males with first UTI (investigate underlying cause)
Asymptomatic bacteriuria: do not treat except in pregnancy or pre-urological instrumentation

Differentials: vaginitis/candidiasis (external dysuria, discharge), urethritis (STI-related), interstitial cystitis, pelvic inflammatory disease, appendicitis/renal colic (flank pain differentials), STI.

Uncomplicated cystitis (women):

Nitrofurantoin 100mg bd × 3-5 days (avoid if eGFR <45), or trimethoprim 200mg bd × 3 days (check local resistance), or fosfomycin 3g single dose
Increase fluid intake, urinary alkalinizers for symptom relief (limited evidence)

Pyelonephritis:

Outpatient (mild, tolerating oral, no red flags): oral ciprofloxacin 500mg bd × 7 days, or co-amoxiclav/cephalosporin per local resistance × 7-14 days
Inpatient (severe, vomiting, sepsis features, pregnancy): IV antibiotics (ceftriaxone, or ciprofloxacin), switch to oral once improving, total course 10-14 days
Identify/manage complications: renal/perinephric abscess (imaging if not improving in 48-72h), obstruction requiring drainage (stent/nephrostomy)

Recurrent UTI (≥2 in 6 months or ≥3 in 12 months): investigate underlying cause, post-coital prophylaxis if coitally-related, low-dose nightly prophylactic antibiotic (nitrofurantoin 50-100mg nocte) if conservative measures fail, vaginal estrogen in postmenopausal women (restores protective flora), consider methenamine hippurate as non-antibiotic option.

Men: always investigate for underlying cause (prostatic, structural) after first UTI — not considered "uncomplicated"; treat 7 days minimum, consider prostatitis if perineal pain/systemic symptoms (requires longer course, 2-4 weeks, quinolone/trimethoprim given prostate penetration).

Pregnancy: treat all bacteriuria (symptomatic and asymptomatic) — nitrofurantoin (avoid near term — neonatal hemolysis risk) or cephalexin; avoid trimethoprim in first trimester (folate antagonist) and avoid quinolones throughout.

Referral: urology for recurrent UTI in men, structural abnormality, stones, treatment-resistant disease; nephrology for recurrent pyelonephritis with renal impairment.

Catheter-related Urinary Tract Infection

Overview

Clinical Features

Diagnosis

Management

Overview

Clinical Features

Diagnosis

Management