Treatment of MRSA in Urine
For asymptomatic MRSA bacteriuria, treatment is generally not recommended as it represents colonization rather than infection and may lead to antimicrobial resistance. 1
Distinguishing Between Asymptomatic Bacteriuria and UTI
- Asymptomatic bacteriuria (ABU) is defined as bacterial colonization of the urinary tract without symptoms, with bacterial growth >10^5 CFU/mL in two consecutive samples for women or in a single sample for men 1
- Treatment should only be considered when MRSA in urine is accompanied by symptoms of urinary tract infection (dysuria, frequency, urgency, suprapubic pain) 1
- Treating asymptomatic MRSA bacteriuria can lead to selection of antimicrobial resistance and eradication of potentially protective bacterial strains 1
When Treatment of MRSA in Urine is Indicated
- Treatment is indicated for symptomatic MRSA urinary tract infections 2, 1
- Treatment should be considered before urological procedures breaching the mucosa 1
- Treatment is recommended for pregnant women with MRSA bacteriuria 1
Treatment Options for Symptomatic MRSA UTI
First-line Options:
- IV vancomycin is the mainstay of parenteral therapy for MRSA infections including UTIs 2, 3
- Linezolid 600 mg PO/IV twice daily is an effective alternative to vancomycin 2, 3
Alternative Options:
- Trimethoprim-sulfamethoxazole (TMP-SMX) can be used if the strain is susceptible 2, 4
- Daptomycin has shown non-inferiority to vancomycin in MRSA bacteremia and can be considered for complicated UTIs with bacteremia 3, 5
- Teicoplanin (where available) is an alternative for patients unable to tolerate vancomycin 6, 4
Special Considerations
Duration of Therapy
- For uncomplicated MRSA UTIs, 7-14 days of therapy is typically recommended 2
- For complicated infections or those with bacteremia, longer courses may be necessary 2, 5
Combination Therapy
- For persistent or severe MRSA infections, combination therapy may be considered 5
- Options include vancomycin combined with a β-lactam or daptomycin-based combination therapy 5
- Rifampin should not be used as monotherapy due to rapid emergence of resistance but may be considered as part of combination therapy 2, 4
Monitoring
- For patients with MRSA UTI, monitor clinical response and consider repeat urine cultures to document clearance 1
- For patients with persistent bacteriuria despite appropriate therapy, evaluate for complications such as abscess, urinary stones, or anatomical abnormalities 1
Pediatric Considerations
- IV vancomycin is recommended for children with MRSA infections 2
- If the patient is stable without ongoing bacteremia, clindamycin can be used as empirical therapy if local resistance rates are low (<10%), with transition to oral therapy if the strain is susceptible 2
- Linezolid dosing for children: 600 mg PO/IV twice daily for children >12 years of age and 10 mg/kg/dose every 8 hours for children <12 years of age 2
- Tetracyclines should not be used in children <8 years of age 2
Common Pitfalls
- Treating asymptomatic MRSA bacteriuria unnecessarily, which contributes to antimicrobial resistance 1
- Failure to remove infected intravascular or prosthetic devices, which is associated with higher relapse and mortality rates 2
- Using rifampin as monotherapy, which rapidly leads to resistance 2, 4
- Inadequate duration of therapy for complicated infections 2