Epigenetics is a very active field of research today. This is a mechanism by which environmental factors can influence gene expression. Indeed, epigenetics has been defined as a new science aimed at studying the mechanisms by which the genotype generates the phenotype, without there being any modifications in the DNA sequence. In this context, we conducted a prospective study on the records of 523 patients hospitalized in the neonatal intensive care unit of the CHU Mohamed VI in Marrakech, over a period of 6 months, from July 01, 2019 to December 31, 2019. Main results obtained were as follows: A high MRB carriage rate affecting 45.5% of hospitalized patients during the study period. Late MRB infections are an important part of this. The analysis of the risk factors of these infections had demonstrated the major role of invasive procedures, in particular mechanical ventilation and KTVO, as well as the high duration of hospitalization which was on average 17.47 days in our study. The bacteriological profile was dominated by enterobacteriaceae, particularly K. pneumoniae and E. cloacae. Of all the MRBs sent to the Kremlin Bicêtre hospital, 55 strains were analyzed by MLST; including 36 strains of K. pneumonia and 19 strains of E. cloacae. The Enterobacteriaceae strains analyzed in our study were mainly carbapenemase producers, of the NDM and OXA-48 type, and ESBL type CTX-15M. Of all the bacterial clones identified, a high rate of resistance to antibiotics, in particular carbapenems, was noted in the following clones: ST 1805, ST 1158 and ST 307. The ST 1805 clone was exclusively found in our series.