Persistent reduction of Bifidobacterium longum in the infant gut microbiome in the first year of life following intrapartum penicillin prophylaxis for maternal GBS colonization
Group B Streptococcus (GBS) is a significant cause of early-onset disease (EOD) in term newborns, with a global incidence of 0.41/1000 live births. Intrapartum antibiotic prophylaxis (IAP) has reduced EOD incidence by over 80%, but concerns exist about its impact on the neonatal gut microbiome and potential long-term health effects. This single center, convenience sample study examines the effects of IAP on the fecal infant microbiome in the first year of life and on the T cell phenotype in the first days after birth. A cohort of 48 mother-infant pairs was followed, 22 infants receiving IAP with penicillin due to maternal GBS colonization (“IAP exposed” group) and 26 infants not exposed to IAP (here referred to as “control group”). The fecal microbiome was analyzed at birth, one month and one year of age through 16S rRNA gene sequencing. Additionally, a T cell panel of peripheral blood was performed between the second and fifth day of age. Results showed age-dependent fecal microbiome changes at one month and one year but only minimal differences in meconium between IAP exposed and control infants. At one month, IAP exposed infants had a significantly lower relative abundance of Bifidobacterium longum in fecal samples, an effect which was sustained at one year. In IAP exposed infants we found a proinflammatory T-helper cell profile, characterized by higher IL-17A, ROR?t, and TGF-ß expression. Microbiome alterations did not translate into relevant differences in health-related outcomes during the first 12 months of age. This study proposes a sustained impact of IAP on the neonatal microbiome and T cell repertoire. Further research efforts are required to develop elaborate strategies to balance benefits of IAP with potential risks for long-term health.