Objectives: The primary objective is to assess if administration of oral vancomycin followed by VE818 to pregnant women colonised with at least 2 out of 11 selected bacterial enteropathogens results in a significant change in the mean count of these organisms between the baseline and 2 weeks after completion of the intervention (Study Day 35d +2), compared to oral vancomycin followed by placebo.

Methods: Pregnant women will be recruited from the community of Matiari in Pakistan. The study population will be women aged 18 years or older in the first trimester or early second trimester of pregnancy. Study procedures will be explained in detail, and written consent will be taken before enrollment. Those women who give consent to participation will undergo a screening process, which will check if any exclusion criteria are fulfilled. After consent and screening, they will be randomised into one of the three arms: intervention arm (oral vancomycin followed by VE818), placebo-control arm (oral vancomycin followed by placebo), or observation-only arm. The allocation sequence will be generated by the trial statistician using a code with block permutation. The participant will remain free to withdraw at any time from the trial without giving reasons and without prejudicing her further treatment. Biological samples, including blood, saliva, urine, stool, vaginal swab, and intestinal luminal contents through CapScan. CapScan is a non-invasive device (capsule) that collects gastrointestinal samples along the gastrointestinal tract following ingestion and passes into the stool. Outcome measures/variables: The primary endpoint is the change in the mean count in the number of 11 selected fecal bacterial pathogen groups present between baseline and 2 weeks after completion of the 14-day course with Placebo or VE818 (Study arms 2 and 3), which corresponds to the 35th day, +2 from the first dose of oral vancomycin. The 11 enteropathogen targets will be detected by customized real-time quantitative PCR-based TaqMan Array Cards (TAC-qPCR) and include the following organisms: Aeromonas, Campylobacter coli, Campylobacter jejuni, Campylobacter Pan, Enteroaggregative Escherichia coli (E. coli), Enteropathogenic E. coli, Enterotoxigenic E. coli, Plesiomonas, Shigella\_Enteroinvasive E. coli (EIEC), Salmonella, and Klebsiella pneumoniae