The Impact of Early Empiric Antibiotics use on Gut Microbiota in Very Low Birth Weight Preterm Infants

Introduction: Antibiotics are frequently prescribed to preterm infants and are known to disrupt microbial balance. Our objective was to determine the impact of different empiric antibiotics use in the first week of life on microbial colonization and diversity in very low birth weight (VLBW) preterm infants.

Methods: Breast fed VLBW infants were divided into two groups, including those who received 3 d of combination treatment of ampicillin and gentamicin (AG group), and those received 7 d of ampicillin and cefotaxime (AC group). Infants with any antibiotics use after age of 7d and infants on exclusive formula feeding were excluded. Stool samples were collected at age of 7d, 14d, and 30d. The 16s ribosomal DNA community profiling was used to compare the microbiota between two groups.

Results: Twenty-four infants were enrolled in our study (AG group =10, AC group =14). The gestation age and birth weight were 30.0± 2.5 weeks and 1286± 190 gm in the AG group versus 28.9± 2.5 weeks and 1099± 280 gm in the AC group, respectively. Infants of AC group had significantly increased abundance of Enterococcus in the 7th day of life compared to those of AG group (12.3% vs 0.6%, P = .032). The richness of species in AC group significantly decreased in the 14d (p= .038) and 30 d(p= .030) samples as compared to that in the 7d sample. The evenness was lowest in the 7d sample of AC group comparing to the14d and 30 d samples (p= .041). The diversity within group had no significant difference between two groups in each time period samples.

Conclusions: Different antibiotic treatments affect the early development of gut microbiota in VLBW preterm infants. A combination of ampicillin and cefotaxime resulted in an overgrowth of Enterococcus and a decreased in richness and evenness.