1. Introduction
- Definition: Live microorganisms which, when administered in adequate amounts, confer a health benefit on the host.
- Goal: To establish a healthy microbiome (commensal flora) in the preterm gut to prevent dysbiosis.
2. Mechanism of Action
- Barrier Enhancement: Strengthens epithelial tight junctions, reducing permeability (“leaky gut”).
- Competitive Inhibition: Competes with pathogens for nutrients and mucosal receptor sites.
- Immunomodulation: Upregulates anti-inflammatory cytokines (IL-10) and downregulates pro-inflammatory cytokines (TNF-α, IL-6).
- Trophic Effects: Increases mucin production and production of Short Chain Fatty Acids (SCFAs) which nourish colonocytes.
3. Evidence and Indications (VLBW Infants)
Current evidence (Cochrane/systematic reviews) supports use in Very Low Birth Weight (VLBW) <1500g infants.
- Necrotizing Enterocolitis (NEC): Significant reduction in NEC (Stage II or higher). Number Needed to Treat (NNT) is approx 20–25.
- Mortality: Significant reduction in all-cause mortality in VLBW infants.
- Late-Onset Sepsis (LOS): Modest reduction in culture-proven sepsis (fungal and bacterial).
- Feed Tolerance: Reduces time to reach full enteral feeds.
4. Strains and Dosage
- Common Strains:
- Bifidobacterium species (e.g., B. lactis, B. infantis) - Dominant in breastfed infants.
- Lactobacillus species (e.g., L. acidophilus, L. rhamnosus GG).
- Saccharomyces boulardii (Yeast) - Generally avoided in central line patients due to fungemia risk.
- Protocol:
- Dose: Typically CFU/day.
- Timing: Start with initiation of enteral feeds; continue until 34–36 weeks PMA or discharge.
- Combination: Multi-strain probiotics are generally considered more effective than single strains.
5. Contraindications and Safety
- Absolute Contraindications:
- Known intestinal anomaly (e.g., Gastroschisis, Omphalocele).
- Short bowel syndrome (risk of D-lactic acidosis with certain strains).
- Immunodeficiency disorders.
- Relative Contraindications/Caution:
- Extreme prematurity (<750g or <26 weeks) - Safety data limited; use with caution.
- Hemodynamic instability/Acute phase of NEC.
- Adverse Events: Probiotic sepsis (bacteremia/fungemia) is the main concern but is extremely rare in reported trials.
6. Summary of Recommendations
- Routine use of probiotics is recommended for preterm infants <32 weeks or <1500g.
- Should be used as an adjunct to breast milk/donor milk.
- Standard quality control is essential as commercial preparations vary in purity.