When to stop intrathecal (within the spinal canal) colistin in neonates?

When to Stop Intrathecal Colistin in Neonates

Intrathecal colistin should be discontinued in neonates when cerebrospinal fluid (CSF) cultures become negative and clinical improvement is observed, typically after 24-36 hours of negative cultures and resolution of clinical symptoms.

Decision Framework for Discontinuing Intrathecal Colistin

Primary Criteria for Discontinuation

• Discontinue intrathecal colistin when all bacterial cultures (including CSF) are negative at 24 to 36 hours 1
• Clinical improvement must be observed (e.g., resolution of fever, improved feeding) 1
• Absence of other infections requiring treatment 1

Monitoring Parameters Before Discontinuation

• Confirmation of microbiological clearance from CSF cultures 1
• Assessment of clinical parameters including:
  • Resolution of meningeal signs and symptoms 1
  • Normalization of vital signs 1
  • Improved feeding behavior 1

Special Considerations

Renal Function and Electrolyte Monitoring

• Monitor renal function closely during colistin therapy due to risk of nephrotoxicity 1
• Check for electrolyte disturbances, particularly hypomagnesemia, hypokalemia, and hyponatremia 2
• Approximately 24% of infants may require electrolyte supplementation during colistin therapy 2

Transition to Other Antimicrobials

• Consider transitioning to systemic antimicrobial therapy after intrathecal colistin discontinuation if continued treatment is needed 1
• For multidrug-resistant gram-negative infections with positive CSF cultures that have cleared, continue systemic antibiotics for the duration appropriate to the specific pathogen and clinical response 1

Safety and Efficacy Data

Clinical Response Rates

• Microbiological clearance with intravenous colistin ranges from 69-91.7% in neonates 3, 2
• When intrathecal administration is added for persistent CSF infections, higher clearance rates can be achieved 3

Common Adverse Effects

• Acute kidney injury occurs in approximately 19% of preterm infants receiving colistin 2
• Electrolyte disturbances, particularly hypomagnesemia, are common but reversible 2
• Neurological side effects including seizures and apnea have been reported in approximately 4.6% of neonates 4

Pitfalls and Caveats

• Avoid premature discontinuation before confirming negative cultures, as this may lead to treatment failure and recurrence 3
• Do not continue intrathecal colistin unnecessarily after microbiological clearance, as prolonged exposure increases risk of toxicity 1
• Remember that colistin-induced nephrotoxicity and electrolyte disturbances are generally reversible in surviving patients 2
• Consider that some neonates may require longer duration of therapy for complicated CNS infections, particularly those with anatomical abnormalities or ventricular shunts 1

Follow-up After Discontinuation

• Continue monitoring renal function and electrolytes for at least 48-72 hours after discontinuation 2
• Perform clinical assessment for any signs of infection recurrence 1
• Consider follow-up CSF analysis if clinical deterioration occurs after discontinuation 1