What is the antibiotic of choice for pyelonephritis (infection of the kidney) in pregnancy?

Antibiotic of Choice for Pyelonephritis in Pregnancy

For pyelonephritis in pregnancy, ceftriaxone (1-2g once daily) is the antibiotic of choice for initial inpatient treatment, followed by oral cephalosporins after clinical improvement for a total treatment duration of 10-14 days. 1

Initial Management Approach

First-line Therapy

• Inpatient treatment is required for pregnant women with pyelonephritis, especially those with:

  • Fever
  • Severe flank pain
  • Nausea/vomiting
  • Signs of sepsis
  • Inability to tolerate oral medications
  • Second or third trimester pregnancy 1

• Initial antibiotic regimen:

  • Ceftriaxone 1-2g IV once daily (higher dose preferred) 1
  • This regimen is supported by multiple studies showing equivalent efficacy to multiple-dose regimens with the convenience of once-daily dosing 2

Diagnostic Workup

• Urinalysis and urine culture with antimicrobial susceptibility testing
• Ultrasound evaluation to rule out urinary tract obstruction or renal stones 1
• Blood cultures (bacteremia occurs in approximately 14% of cases) 3

Treatment Modification

When to Switch to Oral Therapy

• After clinical improvement and afebrile for 24-48 hours 1
• Switch to oral cephalosporins or amoxicillin-clavulanate based on susceptibility results 1

Total Treatment Duration

• 10-14 days of total antibiotic therapy 1

Alternative Regimens

If ceftriaxone is unavailable or contraindicated, alternatives include:

• Cefepime 1-2g IV twice daily
• Piperacillin/tazobactam 2.5-4.5g IV three times daily 1

Important Considerations

Antibiotics to Avoid

• Fluoroquinolones (ciprofloxacin, levofloxacin) should be avoided during pregnancy due to potential fetal risks 1
• Aminoglycosides (gentamicin, amikacin) should also be avoided when possible due to potential fetal risks 1

Follow-up

• Obtain follow-up urine culture 1-2 weeks after completing therapy to confirm clearance 1
• Monthly urine cultures until delivery to monitor for recurrence 1
• Approximately 6.3% of women may develop recurrent pyelonephritis during pregnancy 4

Clinical Pearls and Pitfalls

• E. coli is the predominant pathogen (76-86% of cases) 4, 3
• Bacteremia occurs in 8-14% of pregnant women with pyelonephritis 4, 3
• Consider local resistance patterns when selecting empiric therapy 1
• Outpatient treatment with intramuscular ceftriaxone may be considered for selected patients in early pregnancy (before 24 weeks) who are clinically stable, though inpatient management remains the standard of care 5, 6
• Failure to respond within 48-72 hours may indicate resistant organisms or complications requiring change in antibiotic therapy 1