Impact of intrapartum antimicrobial prophylaxis upon the intestinal microbiota and the prevalence of antibiotic resistance genes in vaginally delivered full-term neonatesOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
Researchers followed 40 full-term, vaginally delivered infants from uncomplicated pregnancies, 18 born to mothers given intrapartum antimicrobial prophylaxis (IAP, penicillin) for group B streptococcus and 22 unexposed. They tracked how IAP shaped the infant gut microbiota over the first three months.
How was it studied?
Fecal samples were collected at 2, 10, 30, and 90 days of age. The team used 16S rRNA gene sequencing to profile microbiota composition, gas chromatography to measure short chain fatty acids, and PCR to detect antibiotic resistance genes in one-month samples.
What did they find?
IAP infants showed lower relative proportions of Actinobacteria and Bacteroidetes and higher Proteobacteria and Firmicutes, most pronounced in the first weeks. Fecal propionate was significantly lower in IAP infants at day 2 (3.1 mM versus 5.3 mM), with a delayed rise in acetate. Beta-lactamase genes, including blaTEM, occurred more often in IAP-exposed infants, though this trend did not reach statistical significance.
Why it matters
IAP reaches over 30% of deliveries, so early disruption of microbiota composition and metabolic activity could affect infant immune and metabolic development during a critical colonization window.