Renal · Year 2 · from Renal
Case 3: Catheter-Associated UTI (CAUTI)
Patient Presentation
Demographics: 72-year-old male
Chief Complaint: Confusion and fever in nursing home resident
History of Present Illness: The patient is a nursing home resident with chronic indwelling Foley catheter for urinary retention due to BPH. Staff noticed he has been more confused than baseline over the past day. He developed fever this morning. He has no dysuria complaint (impaired sensation), but nursing staff note cloudy, foul-smelling urine.
Past Medical History:
- Benign prostatic hyperplasia with urinary retention
- Dementia (moderate)
- Diabetes mellitus type 2
- Hypertension
Medications:
- Metformin, lisinopril, donepezil
Physical Examination:
- Blood pressure: 128/78 mmHg
- Heart rate: 96 bpm
- Temperature: 38.6C
- General: Confused, oriented only to self
- Lungs: Clear
- Abdomen: Soft, mild suprapubic fullness
- Foley catheter in place with cloudy, malodorous urine
Workup and Results
Laboratory Studies:
- WBC: 14,800/mcL
- Creatinine: 1.3 mg/dL (baseline 1.0)
- Urinalysis: Positive leukocyte esterase, many WBC, many bacteria
- Urine culture: Proteus mirabilis 100,000 CFU/mL
Clinical Image
Diagram illustrating catheter-associated urinary tract infection with biofilm formation on the catheter surface, creating a nidus for bacterial colonization and ascending infection.
Diagnosis
Catheter-Associated Urinary Tract Infection (CAUTI)
Criteria met:
- Catheter in place >48 hours (or removed within 48 hours)
- Signs/symptoms of infection (fever, confusion)
- Positive urine culture (>10^5 CFU/mL)
Discussion
This case illustrates CAUTI:
- Definition: The lecture defines CAUTI as requiring symptoms plus catheter in place for at least 48 hours (or within 48 hours of removal). Bacteriuria alone is not CAUTI without symptoms.
- Daily Risk: The lecture notes that bacteriuria risk increases approximately 5% per day of catheterization. After 30 days, essentially all catheterized patients have bacteriuria.
- Atypical Presentation in Elderly: The lecture emphasizes that UTI may present atypically in elderly patients with confusion, falls, or functional decline rather than classic dysuria and frequency.
- Proteus and Biofilm: Proteus species are common CAUTI pathogens. Urease production alkalinizes urine and promotes struvite encrustation on catheters.
Treatment Plan
- Catheter Management (Essential):
- Replace or remove catheter before starting antibiotics
- Assess need for continued catheterization
- Antibiotics:
- Empiric broad-spectrum (ceftriaxone or fluoroquinolone)
- Narrow based on culture results
- Duration: 7 days (10-14 if slow response)
- Supportive Care:
- IV fluids if needed
- Monitor mental status
- Prevention:
- Remove catheter as soon as possible
- If catheter necessary, use closed drainage system
- Daily assessment of catheter necessity
Teaching Points
- CAUTI requires symptoms plus catheter in place >48 hours
- Bacteriuria risk increases ~5% per day of catheterization
- Catheter removal/replacement is essential for treatment success
- Elderly may present atypically (confusion, falls, functional decline)
- Never treat asymptomatic bacteriuria in catheterized patients
Image Reference
For visual reference of UTI concepts, see:
- Radiopaedia: Pyelonephritis - Imaging findings
- Wikimedia Commons: Urinary tract infection - Pathology
- Radiopaedia: CAUTI - Overview
Learning Points
- Uncomplicated UTI: Healthy, non-pregnant woman; empiric treatment without culture
- Fever = Upper Tract: Fever distinguishes pyelonephritis from cystitis
- WBC Casts = Pyelonephritis: Pathognomonic finding localizing infection to kidney
- CAUTI Definition: Symptoms + catheter >48 hours; always remove/replace catheter
- Do Not Treat ASB: Asymptomatic bacteriuria treatment indicated only in pregnancy and before urologic procedures