Associations between cord serum antibodies against phosphorylcholine and bacterial infections in neonates: a prospective cohort study in singletons and twins

BackgroundAntibodies against phosphorylcholine (anti-PC) are reported to protect against infection. However, the association between cord serum anti-PC and bacterial infection in neonates is yet to be investigated. This study aimed to investigate these associations among both singletons and twins. MethodsA total of 1007 neonates (329 singletons and 678 twins) within the hospital-based Shenzhen Baoan Birth & Twin cohort were included in this study. Levels of IgM anti-PC, IgG anti-PC, as well as IgM, IgG, and IgA in cord serum were measured by enzyme-linked immunosorbent assay. Diagnoses of bacterial infections were identified within 0-27 days after birth. Multivariable logistic regression with propensity score adjustment was performed to assess the associations between levels of antibodies and neonatal bacterial infections. ResultsThe mean (standard deviation) levels of IgM and IgG anti-PC were 46.68 (14.15) ng/ml and 73.68 (30.44) ng/ml, respectively. Neonatal bacterial infections were diagnosed in 24 singletons (7.29%) and 48 twins (7.08%). A higher level of IgM anti-PC was associated with a lower risk of neonatal bacterial infections in the analyses of singletons (Odds ratio [OR]: 0.64, 95% confidence interval [CI]: 0.41-0.99) or discordant twin pairs (concerning bacterial infection) (OR: 0.44, 95% CI: 0.20-0.95). Statistically significant association was also shown for IgG among singletons and the first-born twins, but not for IgG anti-PC, IgM, or IgA. ConclusionA higher cord serum level of IgM anti-PC is associated with a lower risk of bacterial infections in neonates. Key pointA higher level of IgM anti-PC in cord serum is associated with a lower risk of bacterial infection in both singleton and twin neonates.