Effect of one prophylactic dose of azithromycin on Bifidobacterium infantis colonization in infants from the Mumta trial

AZ administration was associated with a 1.99-fold (95% confidence intervals [CI] 1.33-2.97) increase in colonization by B. infantis. B. infantis colonization was highest when inflammatory biomarker levels were within normal range. Mode of delivery (RR 2.43; 95% CI: 1.58, 3.76) and colostrum (RR2.05; 95% CI: 1.41, 2.98) given to the infant within 24 h of birth were associated with B. infantis colonization. A single dose of AZ on day 42 reduced bacterial enteropathogen count in the AZ group on day 56, as compared to the pre-AZ count. Bacterial enteropathogen count for infants with wasting (weight for length z-score WLZ <-2) was 1.43-fold higher (95% CI: 1.00-2.03) than for infants with WLZ ≥ -2. Over 60% of infants harbored with the macrolide resistance mph(A) gene CONCLUSION: AZ administration increases B. infantis colonization and reduces bacterial enteropathogen count in infants.