Objective To describe the characteristics of the nasopharyngeal microbiota in children under 5 years of age in Haidong City, Qinghai Province and analyze its associated factors, so as to provide basic data for the evolution and development of nasopharyngeal microbiota in children.

Methods A total of 230 community children from Haidong City, Qinghai Province were included in the study. Participants’ basic information was collected by local volunteers from parents/guardians at enrollment. 16S rDNA sequencing was used to identify the bacterial diversity and abundance of nasopharyngeal microbial community. Bioinformatics methods were used to analyze the characteristics of the nasopharyngeal microbiota, compare the differential species, and investigate the correlation with age.

Results There was no statistical difference in either Chao1 index or Shannon index of nasopharyngeal microbial communities among children with different ages (P>0.05). Besides, the structure of nasopharyngeal microbiota in children of different ages was different, either (P=0.020). Age, ethnicity and delivery mode, to some extent, could explain the differences in the structure of nasopharyngeal microbiota in children. There were statistically significant differences in the abundance of Dolosigranulum,Staphylococcus and Corynebacterium in the nasopharyngeal microbiota of children with different ages (P<0.05). Differential analysis revealed that Corynebacterium was found to be over-represented in children under 1 year of age, while Dolosigranulum was found to be over-represented in children between 2 and 3 years old. Furthermore, the results of correlation analysis showed that, Moraxella was positively correlated with Corynebacterium, Dolosigranulum and Streptococcus, but negatively correlated with Pseudomonas. In addition, a strong positive correlation was detected between the Dolosigranulum and Corynebacterium.

Conclusion The diversity of nasopharyngeal microbial community among children under 5 years in Haidong City, Qinghai Province is stable. However, there are differences in the species structure, mainly in the abundance difference of Dolosigranulum, Staphylococcus and Corynebacterium. This study provides basic data on the evolution and maturation of nasopharyngeal microbial communities in early childhood, which can provide a scientific basis for the early prevention and diagnosis of respiratory tract infections in children.