What is the recommended treatment for a pregnant patient at 28 weeks gestation with a urinary tract infection (UTI) caused by bacteria susceptible only to Rocephin (ceftriaxone) and having an intermediate response to Macrobid (nitrofurantoin)?

Treatment of UTI in 28-Week Pregnant Patient with Bacteria Susceptible Only to Rocephin

Ceftriaxone (Rocephin) is the recommended treatment for this pregnant patient at 28 weeks gestation with a UTI caused by bacteria susceptible only to ceftriaxone with intermediate response to nitrofurantoin. 1

Rationale for Treatment Choice

• The bacteria is only susceptible to ceftriaxone (Rocephin) with intermediate response to nitrofurantoin (Macrobid)
• Ceftriaxone is FDA-approved for urinary tract infections caused by susceptible organisms 1
• Ceftriaxone has maintained excellent activity against common uropathogens in pregnancy with low resistance rates (only 9.1% resistance) 2

Administration and Dosing

For this pregnant patient with UTI:

• Dosage: 1-2 grams of ceftriaxone once daily 1
• Route: Intramuscular (IM) or intravenous (IV) administration
• Duration: Typically 5-7 days, depending on severity and clinical response
• Administration: If IV, administer over 30 minutes 1

For IM administration, reconstitute with appropriate diluent:

• 1g vial: Add 3.6 mL diluent for 250 mg/mL concentration 1
• Inject well within a relatively large muscle 1

Safety in Pregnancy

Ceftriaxone is considered safe in pregnancy:

• Pregnancy Category B - no evidence of embryotoxicity, fetotoxicity, or teratogenicity in animal studies 1
• No adequate controlled studies in pregnant women, but extensive clinical experience supports safety 1
• Reproductive studies in mice and rats at doses up to 20 times the usual human dose showed no evidence of harm to the fetus 1

Monitoring and Follow-up

1. Monitor for clinical improvement within 48-72 hours

2. Assess for potential side effects:

   • Gallbladder pseudolithiasis (more common in pediatric patients) 1
   • Urolithiasis (ensure adequate hydration) 1
   • Rare cases of pancreatitis 1

3. Consider follow-up urine culture 1-2 weeks after completion of therapy to confirm eradication

Special Considerations

• Nitrofurantoin (Macrobid) would typically be a first-line agent for uncomplicated UTIs in pregnancy 3, but with only intermediate susceptibility, it's not the optimal choice in this case
• Single-dose aminoglycosides can be effective for UTIs 4, but susceptibility testing doesn't indicate this as an option
• Ceftriaxone has demonstrated excellent efficacy in complicated and uncomplicated UTIs when administered once daily 5, 6

Potential Pitfalls to Avoid

1. Do not use diluents containing calcium when reconstituting ceftriaxone 1
2. Do not administer simultaneously with calcium-containing IV solutions 1
3. Avoid inadequate hydration during treatment to prevent urolithiasis 1
4. Do not discontinue therapy prematurely even if symptoms resolve quickly

Ceftriaxone once daily has been shown to be highly effective for UTIs, with studies demonstrating favorable outcomes compared to other regimens such as cefazolin given three times daily 5 and cefuroxime 6. This makes it both an effective and convenient option for this pregnant patient with limited treatment options based on susceptibility testing.