RESUMEN
BACKGROUND: Colostrum is rich in microbiota. However, the quantity of microorganisms including both opportunistic pathogens and commensal mammary microbiota remains fluctuant during lactation. And once dysbiosis occurred in these microorganisms, a process in which the population of opportunistic pathogens increases while other bacteria, commensal mammary microbiota decrease. Lactation mastitis might occur. There were few literatures of microbiota in Chinese breastfeeding women. So this study aimed to investigate the quantity of microbiota in the colostrum from healthy breastfeeding women and the milk from mastitis patients in China. METHODS: From January to December 2017, a total of 400 milk samples were collected from the bilateral breasts of 200 women (104 healthy women and 86 mastitis patients). Microbial quantitation was done based on the conserved marker gene 16s rRNA for Bifidobacterium, Lactobacillus, Staphylococcus and Streptococcus by Real-time PCR in all milk samples. The bacterial culture of milk from mastitis patients was also performed. RESULTS: In the colostrum, the amounts of Lactobacillus and Bifidobacterium were significantly higher than those of Staphylococcus and Streptococcus (P<0.0001). The amounts of all the detected bacteria in the colostrum were significantly higher than in the milk from mastitis patients (P<0.01). The same results were obtained in patients with bacteria unrelated mastitis (P<0.01). With respect to colostrum samples, the Staphylococcus copies increased and Bifidobacterium copies declined in cases caused by Staphylococcus aureus or Methicillinresistant Staphylococcus aureus, while both the Staphylococcus and Bifidobacterium copies declined in the milk from patients with Staphylococcus epidermidis or Staphylococcus Lentus induced mastitis (P<0.05). CONCLUSIONS: Results of this study reveal a large amount of microbiota in the colostrum, and mammary microbial dysbiosis may be involved in the pathogenesis of lactational mastitis.