How should I manage a 60-year-old man with a suprapubic catheter who has a nitrate-positive urine dipstick?

Management of Suprapubic Catheter with Positive Urine Nitrite

Do not treat this patient with antibiotics unless he has specific urinary symptoms (fever >38.3°C, suprapubic pain, rigors, hemodynamic instability) or systemic signs of infection. 1

Understanding the Clinical Context

A positive nitrite test in a patient with a suprapubic catheter almost certainly represents catheter-associated asymptomatic bacteriuria (CA-ASB), not infection. 1 In patients with indwelling catheters—whether urethral or suprapubic—bacteriuria and pyuria are nearly universal, approaching 100% prevalence in long-term catheterization. 1

Why Nitrite is Positive

• Nitrite indicates gram-negative bacteria (typically E. coli, Proteus, Klebsiella) that convert dietary nitrates to nitrites after 4+ hours of bladder dwell time 2
• Specificity is excellent (98-100%), meaning bacteria are truly present 2
• However, bacterial colonization of catheters is expected and does not equal infection 1

Diagnostic Algorithm: Does This Patient Need Treatment?

Step 1: Assess for Specific Urinary Symptoms

Treatment is indicated ONLY if the patient has:

• Fever >38.3°C (101°F) 1, 2
• Rigors or shaking chills 1, 2
• New suprapubic pain or costovertebral angle tenderness 1, 2
• Hemodynamic instability (hypotension, tachycardia) 1, 2
• Acute delirium with clear temporal relationship to urinary symptoms 1, 2

Do NOT treat based on:

• Positive nitrite alone 1
• Cloudy or malodorous urine 1, 2
• Non-specific symptoms (confusion, falls, functional decline without fever) 1, 2
• Pyuria on urinalysis 1

Step 2: If Asymptomatic → No Further Action Required

The evidence is unequivocal: screening for and treating CA-ASB in patients with long-term indwelling catheters (including suprapubic) provides no clinical benefit and causes substantial harm. 1

Harms of treating asymptomatic bacteriuria:

• Promotes antimicrobial resistance 1
• Increases risk of reinfection with multidrug-resistant organisms 1
• Exposes patient to adverse drug effects and Clostridioides difficile infection 1, 2
• Does NOT prevent symptomatic UTI, bacteremia, or renal injury 1

This is a Grade A-I strong recommendation from the Infectious Diseases Society of America. 1

Step 3: If Symptomatic → Obtain Culture Before Treatment

If the patient develops fever, rigors, or other systemic signs:

1. Change the suprapubic catheter before collecting the specimen 1
2. Obtain urine culture from the newly placed catheter 1, 2
3. Request Gram stain of uncentrifuged urine if urosepsis is suspected (sensitivity 91-96%, specificity 96%) 1, 2
4. Initiate empiric antibiotics only after culture collection, targeting gram-negative organisms 2

Special Considerations for Suprapubic Catheters

Suprapubic catheters have lower rates of CA-bacteriuria compared to indwelling urethral catheters (relative risk 2.60 for urethral catheterization), but bacteriuria still develops universally with long-term use. 1, 3 The same principles apply: do not screen or treat asymptomatic bacteriuria regardless of catheter type. 1

Common Pitfalls to Avoid

• Never order urine cultures on asymptomatic catheterized patients 1, 2
• Never treat based on urinalysis findings alone without confirming symptoms 1
• Never assume non-specific geriatric symptoms represent UTI without fever or specific urinary complaints 1, 2
• Never continue antibiotics "to complete the course" if the diagnosis was wrong 2

Bottom Line

This 60-year-old man with a suprapubic catheter and positive urine nitrite requires no intervention unless he develops fever, rigors, suprapubic pain, or hemodynamic instability. 1 Treating asymptomatic bacteriuria will only promote resistance and expose him to unnecessary drug toxicity without any clinical benefit. 1, 2