What antibiotic is recommended for treating Staphylococcus hominis bacteriuria?

Antibiotic Treatment for Staphylococcus hominis Bacteriuria

For Staphylococcus hominis bacteriuria, treatment is generally not recommended unless the patient is undergoing an endoscopic urologic procedure with mucosal trauma or has symptoms of urinary tract infection.

When to Treat vs. When Not to Treat

According to the 2019 IDSA guidelines for asymptomatic bacteriuria (ASB), treatment decisions should be based on specific clinical scenarios:

Scenarios Where Treatment IS Recommended:

• Patients undergoing endoscopic urologic procedures with mucosal trauma (strong recommendation, moderate-quality evidence) 1
  • For these patients, a urine culture should be obtained prior to the procedure and targeted antimicrobial therapy prescribed rather than empiric therapy
  • A short course (1-2 doses) of antibiotics is preferred over prolonged therapy

Scenarios Where Treatment is NOT Recommended:

• Asymptomatic patients with:
  • Short-term indwelling urethral catheters (<30 days) (strong recommendation) 1
  • Long-term indwelling catheters (strong recommendation) 1
  • Spinal cord injury (strong recommendation) 1
  • Implanted urologic devices (weak recommendation) 1
  • Planned non-urologic surgery (strong recommendation) 1

Antibiotic Selection for S. hominis When Treatment is Indicated

If treatment is deemed necessary (such as before endoscopic procedures or for symptomatic infection), antibiotic selection should be guided by:

1. First-line options (based on susceptibility testing):

   • Vancomycin (30-60 mg/kg/day IV in 2-4 divided doses) 1
   • Teicoplanin (loading dose followed by maintenance) 1

2. Alternative options (if susceptible):

   • TMP-SMX (160-320/800-1600 mg PO q12h) 1
   • Doxycycline (100 mg PO q12h) 1

3. Duration of therapy:

   • For pre-procedural prophylaxis: 1-2 doses 1
   • For symptomatic UTI: 7-14 days 1

Important Considerations

• S. hominis is a coagulase-negative staphylococcus that is often a contaminant in urine cultures

• Differentiate between true infection and contamination by:

  • Presence of symptoms
  • Colony count
  • Repeated isolation of the same organism
  • Pyuria

• Ciprofloxacin has shown poor results against staphylococcal infections in some studies 2, making it a less optimal choice for S. hominis

Common Pitfalls to Avoid

1. Overtreating asymptomatic bacteriuria: This leads to unnecessary antibiotic exposure, increased resistance, and potential adverse effects without clinical benefit 1

2. Failing to treat before endoscopic procedures: This increases risk of post-procedural sepsis 1

3. Using empiric therapy without culture results: When treatment is indicated, targeted therapy based on susceptibility testing is preferred 1

4. Prolonged treatment courses: Short courses are generally as effective with fewer adverse effects 1

Remember that the decision to treat bacteriuria should be based on clinical presentation and the specific scenario rather than the mere presence of bacteria in the urine.