OBJECTIVE To explore the risk factors for the lower respiratory tract infection in the preschool children and observe the association with monocyte chemoattractant protein-1 (MCP-1) gene polymorphisms.

METHODS A total of 126 preschool children with lower respiratory tract infection who were treated in Shandong First Medical University Affiliated People′s Hospital from Mar 2021 to Mar 2023 were assigned as the study group, meanwhile, 152 healthy preschool children who received physical examination were chosen as the control group. The distribution of pathogens causing the lower respiratory tract infection was analyzed, multivariate analysis was performed for the risk factors for the lower respiratory tract infection, and the frequencies of A/G at 2518 locus of MCP-1 gene were observed and compared between the two groups.

RESULTS Totally 128 strains of pathogens were isolated from the children with infection, 88 (68.75%) of which were gram-negative bacteria, 40 (31.25%) were gram-positive bacteria. Asthma, premature delivery, weekly intake of snack food no less than 7 time, parents′ smoking, low birth weight and high expression levels of peripheral blood MCP-1 were the independent risk factors for the lower respiratory tract infection in the preschool children(P < 0.05). There were no significant differences in the frequencies of A/G genotypes and alleles at 2518 locus of MCP-1 gene between the two groups of research subjects.

CONCLUSION Haemophilus influenzae and Staphylococcus aureus are the predominant species of pathogens isolated from the preschool children with lower respiratory tract infection, and the infection is closely associated with the asthma, premature delivery, weekly intake of snack food no less than 7 time, parents′ smoking, low birth weight and expression levels of peripheral blood MCP-1 but is not associated with MCP-gene.