Risks of microbial colonization in newborn born to mothers with chorioamnionitis

BACKGROUND: Chorioamnionitis, or intra-amniotic infection, is an infection of the membranes and amniotic cavity caused by polymicrobial associations, including Streptococcus agalactiae (SGB), predominantly localised to the lower genital tract of women. The colonization of a infant with GBS occurs as a result of ascending infection from the mother, in the intranatal period during passage through the natural birth canal of the mother. Colonization of the skin and mucous membranes of the infant in the vast majority of cases proceeds without the clinical implementation of the infectious process, only 2-5% of infected newborns develop an infection associated with GBS.

AIM: The aim of the study is to investigate the vaginal and uterine microflora in women with chorioamnionitis and to determine the degree of neonatal colonization.

MATERIALS AND METHODS: A microbiological examination was undertaken in 113 mother–child pairs. Main group (group I): pregnant women with full-term pregnancy (≥37 weeks’ gestation) who were diagnosed with clinical chorioamnionitis and prescribed antibacterial agents, and their newborns (n = 77). Comparison group (group II): 36 pregnant women without clinical chorioamnionitis with a gestational age of ≥37 weeks’ gestation and their newborns with a physiological course of the early neonatal period. Clinical specimens: secretions from the posterior vaginal fornix and the inner surface of the uterine wall at surgical delivery in women in labour with clinical signs of chorioamnionitis (group I) and without clinical manifestations of chorioamnionitis (group II). Material was obtained at the height of body temperature in group I and during the 1^st period of labour in group II. The clinical materials were umbilical cord blood, skin surface of the occipital fold, discharge from the cavity, and discharge from the tracheobronchial tree (in case of respiratory therapy with ventilator therapy).

RESULTS: At bacteriological examination in women of Group I the frequency of microorganism isolation from the vaginal discharge was: Enterococcus faecalis — 31.8%, S. agalactiae (SGB) — 30.3% and Escherichia coli — 24.2%. The proportion of SGB at 10⁶ CFU/ml was 70%. The proportion of E. coli at 10⁶ CFU/ml was 75% and that of Candida albicans 72%. Among microorganisms isolated from the uterine cavity, the proportion of SGB at 10⁶ CFU/ml was 60%, E. coli 100%. Bacteriological testing of the examined children showed that S. agalactiae (SGB), E. faecalis and E. coli were isolated from almost all neonatal loci studied. Comparative studies have shown that the colonisation of newborn infants was most frequently caused by S. agalactiae (SGB), E. faecalis and E. coli. The frequency of maternal transmission of these organisms to the foetus and the newborn is 100% for S. agalactiae (SGB) and 18–50% for E. faecalis and E. coli. In all examined children of the main group and with the presence of S. agalactiae (SGB) in the uterine cavity of their mothers (n = 5), these microorganisms were isolated from different loci (in all cases from the skin surface of the auricular fold and from oral discharge, and in three cases from umbilical cord blood), but clinical manifestations of the infection process did not develop in any child.

CONCLUSIONS: Despite antibiotic therapy for chorioamnionitis in women, the incidence of micro-organism isolation from both the vagina and the uterine cavity remains high. In most cases, newborns from mothers with chorioamnionitis colonised with micro-organisms, including S. agalactiae (SGB), do not develop a clinical picture of an infective process. Further research is needed to develop preventive measures in terms of perinatal and neonatal infections.