Antibiotic use during pregnancy and its effect on maternal and infant fecal resistome : a cohort study

"Nearly 90% of pregnant women in the US take at least one medication during pregnancy, and in more than 40% of cases, that prenatal medication is an antibiotic. Prenatal exposure to antibiotics could shape the total number of antimicrobial resistance genes in stool samples - the fecal resistome - in women, and also in their infants, who acquire his or her initial microbiome by vertical transmission. We examined 51 pregnant women enrolled during their third trimester of pregnancy in Lansing and Traverse City, MI, and in 42 6-month-old infants to evaluate the association between prenatal antibiotic use and fecal resistome patterns. Prenatal antimicrobial exposure in mothers was assessed using clinical and questionnaire data. Antibiotic resistance gene (ARG) and mobile genetic element (MGE) richness and abundance were assessed using multiplex qRT-PCR. Alpha and Beta diversity were measured. Wilcoxon non-parametric test was used for comparisons. Infants had both significantly greater relative abundance and higher diversity of MGE than their mothers (Shannon diversity and Inverse Simpson p<0.05). We found a high variability of shared patterns between women and their infants, with an average of 29% ARG being shared between dyads. Mother and infant samples are different in terms of ARG and MGE relative abundance and absence/presence data (Adonis p<0.0001). We found differences in specific ARGs diversity among antibiotic exposed vs. non-exposed groups using medical records."--Page ii.