Epidemiologic characteristics of immunoglobulin M antibodies in lower respiratory tract infection pathogens of children: association with severe pneumonia in Chengdu city from 2019 to 2023.

OBJECTIVE: To analyze the epidemiologic characteristics of serum immunoglobulin M (IgM) antibody aming six pathogens in children with acute lower respiratory tract infections (LRTI) and its association with severe pneumonia, thereby providing a basis for clinical diagnosis and treatment.

METHODS: A total of 25,693 children with lower respiratory tract infections who were hospitalized in the Department of Respiratory Medicine at Chengdu Women's and Children's Central Hospital from 2019 to 2023 were included and retrospectively analyzed in the study. The epidemiologic characteristics of serum IgM antibodies for six LRTI pathogens in the enrolled children were analyzed. Logistic regression analysis was conducted to identify risk factors for severe pneumonia.

RESULTS: The IgM positive detection rate among the six pathogens was 30.26%. In addition, the IgM positive detention rates among Mycoplasma pneumoniae (MP), Parainfluenza virus (PVI) and Influenza B virus (IFV-B) of female children were higher than those of male children (P < 0.05); Children who were younger than 1 year oldshowed the lowest IgM positive detention rates of MP and IFV-B (P < 0.05). The positivity rates of IgM antibodies for MP, IFV-B, PIV, and Respiratory syncytial virus (RSV) markedly varied across different lower respiratory tract infections (P < 0.001; P = 0.007; P = 0.004; P < 0.001). The IgM positive detection rate of two or more pathogens before COVID-19 pandemic were higher in comparison to those post COVID-19 (P < 0.05). Compared to the non-severe group, children with severe pneumonia showed a relatively lower detection rate of MP but a significantly higher detection rate of RSV. The results of multiple logistic regression analysis suggested that age and gender were independent influencing factors for severe pneumonia, with an area under the Receiver Operating Characteristics curve of 0.727.

CONCLUSION: In Chengdu city, the positivity rates of IgM antibodies for LRTI pathogens in children exhibited seasonal, age-related, and diagnostic category characteristics-related variations. Severe pneumonia cases were characterized by RSV infection and younger age. Clinicians should take epidemiologic features into consideration to optimize their diagnostic and therapeutic strategies.