Inclusion Criteria:  For the epidemiological study :  All members of 60 households in which a newborn baby has just been born  Inclusion criteria for the mother at the time of childbirth, pregnant woman :  _ having a monofetal pregnancy  residing regularly in the study area OR planning to reside in the study area during the study period; having been informed of the research and collection of biological samples on herself and her newborn; having given its agreement to carry out the research and the associated collection of biological samples, and; having signed the informed consent (or its witness if applicable).  Inclusion criteria for the live newborn at the time of childbirth, new born :  living after childbirth; whose parents or legal representatives present: reside regularly in the study area or plan to reside in the study area during the study period; were informed of the research and the associated collection of biological samples on their newborn; have given their agreement to carry out the research and the associated collection of biological samples,  Inclusion criteria for the household member, resident:  from the same household as the mother-child (ren) couple included Residing at least 4 nights per week in this home Having given its agreement to carry out the research and the associated collection of biological samples, and having signed the consent of the study (or its witness, or its legal representative if applicable)  for the anthropological study with interviews : 16 homes will be selected from among the 60 homes included: 8 homes in which the child has not acquired an ESBL-E during the entire follow-up and 8 homes in which the child has acquired an ESBL-E at least once during its follow-up. Among these households, interviews will be carried out with: 16 mothers or first responsible for the child in the absence of the mother 4 people with a mothering role on the child (grandmother, aunts ...) 4 minors in the families to observe 4 fathers or father figures in families to observe  Also, interviews will be done with:  Health actors: medical (1 midwife and 1 neighborhood doctor) and traditional (1 matron and 1 traditional practitioner from the neighborhood), 1 community health worker 1 neighborhood chief  Inclusion criteria for semi-structured interviews :  people responding to the structuring functions of the child's social and family environment Having given its agreement to carry out the research, and having signed the consent of the study (or its witness, or its legal representative if applicable)  For health workers and district managers, inclusion criteria for semi-structured interviews :  people responding to the targeted functions working in the district of homes included Having given its agreement to carry out the research, and having signed the consent of the study (or its witness, or its legal representative if applicable)  For the anthropological study with observations 4 households in total among the 16 initially selected for the interviews: 2 households in which the child did not acquire ESBL-E during all the follow-up and 2 households in which the child acquired at least once an BLSE-E during his follow-up Inclusion criteria for participating direct observations  Residents of the same household as the mother-child (ren) couple included having agreed to participate in the study Having given its agreement to carry out the research, and having signed the consent of the study (or its witness, or its legal representative if applicable)  Exclusion Criteria:  For the epidemiological part:  Pregnant woman: non-monofetal pregnancy Newborn: died during childbirth Household resident: None and 3) For the anthropological part: • Semi-structured interview:  For household members:  not responding to the structural family and social functions of the child's environment For health workers and district managers people not meeting the targeted functions  not practicing in the district of homes included  • Participant direct observation:  Not living in the same household as the mother-child couple included