What is the recommended treatment for a patient with Methicillin-resistant Staphylococcus aureus (MRSA) urine culture greater than 100,000 Colony-Forming Units per milliliter (CFU/mL) with no symptoms?

Management of Asymptomatic MRSA Bacteriuria

Do not treat asymptomatic bacteriuria with MRSA in the urine culture >100,000 CFU/mL when the patient has no symptoms. 1

Understanding Asymptomatic Bacteriuria

Asymptomatic bacteriuria (ABU) is defined as bacterial colonization of the urinary tract without causing symptoms. According to the European Association of Urology (EAU) guidelines:

• ABU corresponds to commensal colonization and should not be treated in most cases 1
• In individuals without urinary tract symptoms, ABU is defined as a mid-stream urine sample showing bacterial growth >10^5 CFU/mL in two consecutive samples for women or in a single sample for men 1
• The spectrum of bacteria in ABU is similar to species found in uncomplicated or complicated UTIs, depending on the presence of risk factors 1

Evidence-Based Recommendations Against Treatment

The EAU guidelines provide strong recommendations against screening or treating asymptomatic bacteriuria in the following populations:

• Women without risk factors 1
• Patients with well-regulated diabetes mellitus 1
• Postmenopausal women 1
• Elderly institutionalized patients 1
• Patients with dysfunctional and/or reconstructed lower urinary tract 1
• Patients with recurrent urinary tract infections 1

Rationale for Non-Treatment

There are several important reasons to avoid treating asymptomatic bacteriuria:

• Clinical studies have shown that ABU may actually protect against superinfecting symptomatic UTIs 1
• Treating ABU can lead to selection of antimicrobial resistance 1
• Treatment may eradicate potentially protective ABU strains 1
• Unnecessary antibiotic use contributes to the growing problem of antimicrobial resistance 1

Specific Considerations for MRSA

While the guidelines don't specifically address MRSA bacteriuria, the principles remain the same:

• MRSA in urine without symptoms represents colonization rather than infection 1
• Treatment would require MRSA-specific antibiotics like vancomycin, which have significant side effects and contribute to antimicrobial resistance 1
• The Infectious Diseases Society of America (IDSA) guidelines for MRSA infections do not recommend treatment for asymptomatic colonization in any body site 1

When Treatment Should Be Considered

There are specific scenarios where screening and treating asymptomatic bacteriuria is recommended:

• Before urological procedures breaching the mucosa 1
• In pregnant women 1

However, in the absence of these specific indications and without urinary symptoms, treatment of MRSA bacteriuria >100,000 CFU/mL is not recommended.

Monitoring Recommendations

For a patient with asymptomatic MRSA bacteriuria:

• Monitor for development of symptoms (dysuria, frequency, urgency, suprapubic pain) 1
• If persistent growth of urease-producing bacteria is detected, consider evaluation for urinary stones 1
• For male patients, consider digital rectal examination to investigate possible prostate disease 1

Remember that the presence of MRSA in the urine without symptoms does not require antimicrobial therapy, and unnecessary treatment may lead to adverse outcomes including selection of more resistant organisms.