RESUMO
OBJECTIVE: There is an increasing evidence of the immunological role of breast milk (BM) microbiota on infant health. This study aims to analyze several determining factors of milk microbiota. STUDY DESIGN: A total of 96 milk samples from 32 healthy mothers (19 preterm vs 13 at term gestations; and 15 vaginal deliveries vs 17 Cesarean sections) were longitudinally collected. Microbiota composition was studied by quantitative PCR and the influence of lactation stage, gestational age and delivery mode was evaluated. RESULT: Globally, Lactobacillus, Streptococcus and Enterococcus spp. were the predominant bacterial groups. Total bacteria, Bifidobacterium and Enterococcus spp. counts increased throughout the lactation period. At all lactation stages, Bifidobacterium spp. concentration was significantly higher in milk samples from at term gestations than in preterm gestations. Higher bacterial concentrations in colostrum and transitional milk were found in Cesarean sections. Nevertheless, Bifidobacterium was detected more frequently in vaginal than in Cesarean deliveries. CONCLUSION: Lactation stage, gestational age and delivery mode all influence the composition of several bacteria inhabiting BM: Bifidobacterium, Lactobacillus, Staphylococcus, Streptococcus and Enterococcus spp., and, consequently, may affect the infant's early intestinal colonization.
