Association of histological chorioamnionitis and fetal inflammatory response with pathogen distribution in neonatal umbilical cord blood cultures

Objective To investigate the association between different stages of histological chorioamnionitis (HCA), complicated fetal inflammatory response syndrome (FIRS), and the distribution characteristics of pathogens in neonatal umbilical cord blood cultures(UCBC), so as to provide a basis for the early clinical identification of intrauterine infection. Methods A retrospective case-control study was conducted, enrolling 243 newborns delivered at Women's Hospital School of Medicine Zhejiang University from January 2021 to December 2024. According to the results of UCBC, the newborns were divided into a positive group (81 cases) and a negative group (162 cases, matched at a ratio of 1:2). Baseline data such as HCA and FIRS were compared between the two groups, and the high-risk factors affecting positive UCBC results were analyzed. Multivariate logistic regression was used to screen independent risk factors for positive UCBC. Furthermore, the distribution characteristics of pathogens in UCBC under different stages of HCA and FIRS were analyzed. Results The incidence rates of moderate to severe HCA, FIRS, placental abruption, acute chorioamnionitis, maternal prenatal temperature ≥ 38.0℃, maternal prenatal pathogenic infection, and maternal pregnancy complicated by cervical incompetence in the UCBC positive group were significantly higher than in the UCBC negative group (P < 0.05), and the maternal age was older (P < 0.05). Multivariate logistic regression analysis identified that FIRS (OR = 6.38, 95%CI: 2.793–14.573, P < 0.001) and prenatal pathogenic infection (OR = 6.049, 95%CI: 2.946–12.418, P < 0.001) were independent risk factors for positive UCBC. A total of 86 pathogenic strains were isolated from 81 positive UCBC specimens (5 cases of mixed infection), including 51 Gram-positive strains (59.3%), mainly Enterococcus faecalis (14.0%), group B Streptococcus (7.0%) and Streptococcus mitis (7.0%); 35 Gram-negative strains (40.7%), mainly Escherichia coli (29.1%). Among children with positive UCBC results, the rate of moderate or severe HCA was higher than that in the normal or mild HCA group (55.6% vs 44.4%), but the difference was not statistically significant (P > 0.05). The difference between the group with FIRS and the group without FIRS was statistically significant (61.7% vs 38.3%, P < 0.05). Escherichia coli(E. coli) detection was significantly higher in HCA complicated with FIRS than in those without FIRS (68.0% vs 32.0%, P < 0.05). All Listeria monocytogenes infections were accompanied by moderate or severe HCA and FIRS. Conclusion FIRS and maternal prenatal infectious pathogens are independent predictors of positive UCBC.For HCA complicated with FIRS, Gram-negative pathogens such as E. coli should be prioritized in empirical antibiotic coverage.