RecruitingPerinatal Transmission of MDR BacteriaThe investigators aim to conduct a prospective surveillance study of mothers and their infants born vaginally or by scheduled C-section and who are admitted to Northwestern Medicine Prentice Women's Hospital to determine the prevalence of ESBL-E carriage in healthy post-partum women and the transmission rate of these strains to their infants. Using whole genome sequencing and a comparative genomics approach the investigators will determine the relatedness of strains among mother-infant dyads as well as identify genetic regions common to transmitted strains. It is hypothesize that; 1) given the diverse population of Chicago there will be a significant rate of gut colonization with ESBL-E among mothers admitted to Prentice, 2) ESBL-E strains isolated from neonates will be identical to those from their mothers and 3) genetic determinants of transmission are conserved across ESBL E. coli strains that are perinatally transmitted. These hypotheses will be tested using the following Aims: Aim 1: Determine the prevalence of ESBL-E gut colonization and rate of perinatal transmission among mother-infant dyads Aim 2: Identify genetic determinants of transmission common to ESBL E. coli that are perinatally transmitted. The long-term goal is to understand the unique features of persistent gut and vaginal ESBL-E colonizers and identify genetic and molecular elements that could be attractive therapeutic targets to decrease the burden of ESBL-E colonization and perinatal transmission.