Breast milk is a constant source of commensal and beneficial bacteria, including lactic acid bacteria and bifidobacteria. These microorganisms play an important role in the development and optimization of the intestinal microbiota of the newborn due to their pre- and probiotic components. In this experiment, we investigated the qualitative and quantitative composition of the microbiota of mothers' breast milk, and also assessed the influence of the mother's microbiota on the early bacterial colonization of the intestines of newborns. The most common breast milk microbial isolates were Staphylococcus epidermidis, Staphylococcus hominis, and Streptococcus salivarius. Among lactic acid bacteria, Lactobacillus salivarius, Lactobacillus gasseri, Lactobacillus paracasei, Lactobacillus agilis, and Bifidobacterium longum were the most common. We found that the bacterial profile of infant meconium is similar to that of mother's milk. The total number of microorganisms in 1 g of meconium varied from 3.6 log CFU/g to 5.8 log CFU/g. Staphylococci and fecal streptococcus were predominant (55.7% on average). The number of lactobacilli varied from 8% to 23%. Most of the microorganisms isolated from breast milk, meconium, and feces of monthly infants are multiresistant to antibiotics. The isolated microorganisms were most resistant to benzylpenicillin, doxycycline, ampicillin, oleandomycin, oxacillin, fosfomycin, and lincomycin.