Study On Skin Microecology Of Newborns Three Months After Birth And Its Correlation With AD

Objective:by collecting skin microbiological samples from newborns three months after birth and analyzing their microbiome,combined with the incidence of atopic dermatitis（AD）during this period,the relationship between early skin microecology and early onset of AD was studied.Methods:the newborns born to the expectant mothers in the obstetrics department of our hospital from June 2019 to October 2019were followed up for half a year after birth to observe the incidence of AD.Skin samples were taken from cheek（predilection sites of AD）and buttocks（non-predilection site of AD）at day 1,day 3,day 14,day 42 and3 months after birth.The clinical signs and related data of the infants at each sampling time were recorded.After half a year of follow-up,the infants were divided into AD group and control group according to whether AD was diagnosed or not.All skin samples were sequenced by16S-r DNA,and the detection results were statistically analyzed,such asαdiversity,βdiversity,species classification,significant difference and so on.Results:a total of 28 newborns（1 pair of twins）were enrolled in the group,24（85.7%）completed the study and 4 lost follow-up.There were14 patients in AD group and 10 patients in control group.The average age of onset in AD group was 82.9±34.2days,the earliest one is on 28days and the latest is on 150 days.The OR value of atopic history of parents between the two groups was 1.667,which was not statistically significant.（1）comparison of cheek between AD group and control group:αdiversity decreased in both groups.βdiversity analysis was no statistical difference.The genus classification histogram showed that Streptococcus,Staphylococcus and Rothia were dominant bacteria.The proportion of Streptococcus decreased significantly with time in AD group.The abundance of Rothia in the AD group was higher than that in the control group,and increased obviously on the 42^nd day.Staphylococcus fluctuated between the two groups.Significant difference analysis showed that Streptococcus spp.and Staphylococcus hominis had high influence in the AD group and the control group,but there was no statistical significance（P=0.06,LDA=3.23;P=0.12,LDA=4.52）.（2）comparison of buttocks between AD group and control group:theαdiversity of the AD group showed an upward trend,while that of the control group was the opposite.There was no statistical difference inβdiversity.The genus classification histogram showed that the dominant flora of the two groups changed greatly,and the common genus were Enterococcus,Streptococcus and Staphylococcus.The relative abundance of Streptococcus was higher in the AD group and lower than that in the control group after 42^nd days.The abundance of Enterococcus was higher within day 14 after birth,and then decreased.The abundance of Streptococcus in the AD group was lower than that in the control group.Significant difference analysis showed that there was statistical difference between Staphylococcus hominis and Staphylococcus epidermidis（P=0.035,LDA=5.41;P=0.045,LDA=5.58）,and the abundance of both species in the control group was higher than that in the AD group.（3）comparison of cheek and buttocks in AD group:the Observed OTUs and Shannon index of cheek was higher than that of buttocks inαdiversity analysis,but there was no significant difference.βdiversity analysis showed that there was significant difference between the two sites（P<0.001）.The genus classification histogram showed that the cheek was mainly colonized by Streptococcus,Staphylococcus and Rothia,and the buttocks were mainly Streptococcus,Enterococcus and Staphylococcus.Significant difference analysis showed that there were significant differences between Streptococcus pneumoniae and Enterococcus faecalis（P<0.01,LDA=6.28;P=0.005,LDA=4.78）.The abundance of Streptococcus pneumonia in cheek was higher than that of buttocks,while the abundance of Enterococcus faecalis was on the contrary.Conclusion:the abundance and diversity of microflora decreased during the onset of AD.Among them,the genus of Staphylococcus may play an important role in the early pathogenesis of AD,the abundance of genus of Streptococcus decreases significantly during the onset of AD,and the colonization of oral and upper respiratory tract flora in the cheek may be related to the pathogenesis of AD.