What is the treatment for a urinary tract infection with multidrug-resistant organisms (MDRO) in pregnancy?

Treatment of Urinary Tract Infections with Multidrug-Resistant Organisms in Pregnancy

The treatment of UTIs caused by multidrug-resistant organisms (MDROs) in pregnancy requires infectious disease consultation and antimicrobial therapy based on culture and susceptibility testing, with preference for pregnancy-safe antibiotics such as nitrofurans, fosfomycin trometamol, and third-generation cephalosporins.

Diagnostic Approach

• Obtain urine culture and antimicrobial susceptibility testing for all suspected UTIs in pregnancy
• Perform ultrasound to rule out urinary tract obstruction or renal stone disease
• If patient remains febrile after 72 hours of treatment or if clinical deterioration occurs, consider additional imaging (MRI preferred in pregnancy to avoid radiation)

Treatment Principles for MDRO UTIs in Pregnancy

First-Line Options (Based on Susceptibility)

• Nitrofurantoin - for uncomplicated lower UTIs (cystitis) 1

  • Dosage: 100 mg PO four times daily
  • Duration: 5-7 days
  • Contraindicated near term (>36 weeks) due to risk of hemolytic anemia in the newborn

• Fosfomycin trometamol - for uncomplicated lower UTIs 1

  • Dosage: 3 g PO single dose
  • May repeat if needed based on culture results

• Third-generation cephalosporins - for both lower and upper UTIs 1, 2

  • Cefixime (oral): 400 mg daily
  • Ceftriaxone (IV): 1-2 g daily (for pyelonephritis)
  • Duration: 7-14 days (depending on severity)

For Complicated/Severe Infections

• Initial parenteral therapy for pyelonephritis or severe infections 3:

  • Ceftazidime-avibactam 2.5 g IV q8h (for CRE) 3
  • Meropenem-vaborbactam 4 g IV q8h (for CRE) 3
  • Piperacillin/tazobactam 3.375-4.5 g IV q6h 3
  • Aminoglycosides (with careful monitoring) 3

• Step-down to oral therapy once clinically improved:

  • Based on culture and susceptibility results
  • Duration should follow standard UTI treatment guidelines (not extended for MDROs) 3

Special Considerations

For Specific MDROs

• Carbapenem-resistant Enterobacterales (CRE):

  • Ceftazidime-avibactam is recommended for complicated UTIs 3
  • Plazomicin 15 mg/kg IV q12h may be considered 3

• Vancomycin-resistant enterococci (VRE):

  • Linezolid 600 mg IV q12h 3
  • Fosfomycin 3 g PO single dose (for uncomplicated UTI) 3

Duration of Treatment

• Asymptomatic bacteriuria: 3-5 days 3
• Uncomplicated cystitis: 5-7 days 1
• Pyelonephritis: 7-14 days 3, 2
• No evidence suggests that MDROs require longer treatment than standard durations if the antibiotic has activity against the organism 3

Monitoring and Follow-up

• Repeat urine culture 7 days after completing therapy to confirm cure 4
• Monthly screening for recurrent bacteriuria throughout pregnancy 2
• If recurrent infections, consider prophylactic antibiotics after initial treatment 3

Important Caveats

1. Avoid fluoroquinolones due to potential adverse effects on fetal cartilage development unless benefits clearly outweigh risks 2

2. Avoid trimethoprim in the first trimester due to risk of neural tube defects 5

3. Infectious disease consultation is highly recommended for all MDRO infections in pregnancy 3

4. Source control is critical if there is obstruction (e.g., kidney stones) - urgent decompression may be required before definitive treatment 6

5. Antimicrobial stewardship is important - use narrow-spectrum agents when possible based on susceptibility results 3

By following these guidelines and consulting with infectious disease specialists, clinicians can effectively manage UTIs caused by MDROs in pregnancy while minimizing risks to both mother and fetus.