Do I need to treat Staphylococcus haemolyticus found in a urine culture?

Treatment of Staphylococcus haemolyticus in Urine

Do not treat Staphylococcus haemolyticus bacteriuria unless the patient has both acute urinary symptoms (dysuria, frequency, urgency, fever >38.3°C, or gross hematuria) AND pyuria (≥10 WBCs/HPF or positive leukocyte esterase). 1

Diagnostic Algorithm

Step 1: Assess for Specific Urinary Symptoms

• Required symptoms include: acute-onset dysuria, urinary frequency, urgency, fever >38.3°C, gross hematuria, or suprapubic pain 1
• Non-specific symptoms that do NOT justify treatment: confusion, falls, functional decline in elderly patients, or cloudy/malodorous urine alone 1
• If no specific urinary symptoms are present: this represents asymptomatic bacteriuria and should NOT be treated 1

Step 2: Confirm Pyuria

• Pyuria must be present: ≥10 white blood cells per high-power field on microscopy OR positive leukocyte esterase test 1
• Without pyuria: urinary tract infection is unlikely even with symptoms, and treatment should be withheld 1

Step 3: Evaluate Patient Risk Factors

Staphylococcus haemolyticus is an opportunistic pathogen typically found in specific contexts 2, 3:

• Recent urinary catheterization (present in 82% of staphylococcal bacteriuria cases) 4
• Urological abnormalities or recent instrumentation 5, 4
• Immunocompromised states: diabetes, malignancy, stroke, advanced age (>66 years) 2
• Male sex and older age 5

When Treatment IS Indicated

Treat only when ALL of the following are met:

1. Acute urinary symptoms present (dysuria, frequency, urgency, fever, hematuria) 1
2. Pyuria confirmed (≥10 WBCs/HPF or positive leukocyte esterase) 1
3. Pure culture of S. haemolyticus from properly collected specimen 1
4. Patient has risk factors (catheterization, urological abnormality, immunocompromise) 5, 4, 2

Antibiotic Selection

Based on susceptibility data, S. haemolyticus is typically susceptible to 2, 3:

• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 7-14 days (first-line if susceptible) 2, 3
• Nitrofurantoin 100 mg twice daily for 5-7 days (if susceptible and normal renal function) 2
• Vancomycin (reserved for resistant isolates or severe infection) 2

Duration: 7-14 days for complicated UTI or when urological abnormalities are present 1

Special Considerations

Before Urological Procedures

• Screen for and treat S. haemolyticus bacteriuria prior to endoscopic urologic procedures with anticipated mucosal trauma (e.g., transurethral resection, ureteroscopy) 1
• This is the primary exception where asymptomatic bacteriuria should be treated 1

Catheterized Patients

• Do NOT screen or treat asymptomatic bacteriuria in patients with short-term (<30 days) or long-term indwelling catheters 1
• Bacteriuria and pyuria are nearly universal in catheterized patients (approaching 100%) 1
• Only evaluate if: fever, hypotension, rigors, or suspected urosepsis develops 1

Risk of Bacteremia

• S. aureus (closely related species) bacteriuria is associated with subsequent bacteremia in 13% of cases at initial isolation and 11% during follow-up 4
• Consider blood cultures if: patient has fever, hemodynamic instability, or recent urological instrumentation 5, 4
• However, routine blood cultures are NOT recommended in well, asymptomatic patients 5

Critical Pitfalls to Avoid

1. Never treat based on positive culture alone without symptoms and pyuria—this represents asymptomatic bacteriuria in 15-50% of elderly patients 1

2. Do not treat non-specific geriatric symptoms (confusion, falls) without acute urinary symptoms—treatment provides no benefit and increases antimicrobial resistance 1

3. Avoid routine screening in catheterized patients—bacteriuria is universal and treatment increases resistance without preventing symptomatic infection 1

4. Ensure proper specimen collection—contamination is common; use midstream clean-catch or catheterization for definitive diagnosis 1

5. Do not assume all coagulase-negative staphylococci are contaminants—S. haemolyticus can cause true infection in immunocompromised hosts and requires proper identification 2, 3

Harms of Unnecessary Treatment

Treating asymptomatic S. haemolyticus bacteriuria causes 1:

• Increased antimicrobial resistance at individual and health system levels
• Clostridioides difficile infection risk
• Adverse drug effects without clinical benefit
• Reinfection with more resistant organisms
• No reduction in symptomatic UTI, renal injury, or mortality 1