What alternative antibiotic can be used for a baby with a Pseudomonas (Pseudomonas aeruginosa) urinary tract infection (UTI) who cannot tolerate ciprofloxacin (Cipro)?

Alternative Antibiotics for Pseudomonas UTI in Infants Unable to Tolerate Ciprofloxacin

For infants with Pseudomonas aeruginosa UTI who cannot tolerate ciprofloxacin, gentamicin is the recommended alternative treatment option. 1, 2

First-Line Alternative Options

• Gentamicin is the preferred alternative for babies with Pseudomonas UTI who cannot tolerate ciprofloxacin, with dosing based on age and weight 1, 2:

  • Neonates with gestational age <30 weeks:
    • Postnatal age <14 days: 5 mg/kg/dose IV q48h
    • Postnatal age >14 days: 5 mg/kg/dose IV q36h
  • Neonates with gestational age 30-34 weeks:
    • Postnatal age ≤14 days: 5 mg/kg/dose IV q36h
    • Postnatal age >14 days: 5 mg/kg/dose IV q24h
  • Neonates with gestational age ≥35 weeks:
    • Postnatal age ≤7 days: 4 mg/kg/dose IV q24h
    • Postnatal age >7 days: 5 mg/kg/dose IV q24h

• Ceftazidime is another effective alternative for Pseudomonas UTI in infants, with dosing 1:

  • 3 to <6 months: 40 mg/kg/dose IV q8h
  • 6 months and older children: 50 mg/kg/dose IV q8h

Treatment Considerations

• Antibiotic selection should always be guided by susceptibility testing to ensure effectiveness against the specific Pseudomonas strain 3

• For severe infections or in immunocompromised infants, combination therapy may be considered, typically using an aminoglycoside (like gentamicin) with an antipseudomonal β-lactam (like ceftazidime) 1, 3

• Meropenem can be used for resistant strains with the following dosing 1:

  • Gestational age <32 weeks:
    • Postnatal age <14 days: 20 mg/kg/dose IV q12h
    • Postnatal age ≥14 days: 20 mg/kg/dose IV q8h
  • Gestational age ≥32 weeks:
    • Postnatal age <14 days: 20 mg/kg/dose IV q8h
    • Postnatal age ≥14 days: 30 mg/kg/dose IV q8h

Monitoring and Duration

• When using gentamicin, monitor serum concentrations and renal function to minimize toxicity 1

• Treatment duration typically ranges from 7-14 days depending on infection severity and clinical response 3

• For complicated UTIs or in immunocompromised hosts, extended therapy (10-14 days) may be necessary 3

Special Considerations

• For multidrug-resistant Pseudomonas, consultation with a pediatric infectious disease specialist is recommended 1

• Colistin can be considered for multidrug-resistant strains when other options are not viable, with dosing of 2.5-5 mg CBA/kg/day IV in 2 or 4 divided doses 1

• Piperacillin-tazobactam is another option for infants with Pseudomonas UTI, with dosing based on postmenstrual age 1:

  • Postmenstrual age ≤30 weeks: 100 mg/kg/dose IV q8h (piperacillin component)
  • Postmenstrual age >30 weeks: 80 mg/kg/dose IV q6h (piperacillin component)

Common Pitfalls and Caveats

• Underestimating the potential for rapid resistance development during monotherapy is a common pitfall, particularly with Pseudomonas infections 3

• Inadequate dosing can lead to reduced efficacy and increased resistance development 3

• For babies with underlying conditions (such as urinary tract abnormalities), longer treatment courses and follow-up cultures may be necessary to ensure complete eradication 4

• While oral options are limited for Pseudomonas in infants, parenteral therapy followed by oral step-down therapy may be considered in older children once clinical improvement is observed 5