Group B streptococcus neonatal umbilical colonization managed by dry cord care in nurseries: A retrospective cohort study

Background: Screening-based intrapartum antibiotic prophylaxis (IAP) has reduced the prevalence of early-onset group B Streptococcus (GBS) infection in newborns. Nevertheless, early onset disease still occurs despite IAP, and IAP is not effective in preventing late-onset disease. This study aimed to determine the prevalence and risk factors of GBS neonatal umbilical colonization managed by dry cord care in Japan. Methods: Of 735 healthy newborns in the well-baby nursery at Saitama City Hospital, 353 from whom umbilical bacterial swabs were obtained before discharge were included in the analysis. Maternal and neonatal clinical characteristics were retrospectively reviewed. Results: GBS was detected in 4.2% (15/353) of umbilical swabs; 13/15 (86.8%) were born to GBS-negative mothers. The median (IQR) age at umbilical swab collection was 4.0 (4.0-5.0) days. Comparison of clinical characteristics between GBS-positive and negative neonates revealed a significant difference in the proportion of vaginal deliveries (15/15 [100%] in GBSpositive neonates vs. 115/338 [34.0%] in GBS-negative neonates, p < 0.0001). Of 15 GBSpositive neonates, 10 (66.7%) were also co-colonized with other enteric bacteria such as Escherichia coli. Conclusion: Vaginal delivery was a risk factor associated with GBS neonatal umbilical colonization in Japanese neonates. Co-colonization with multiple enteric bacterial species implicates vertical transmission of GBS from undetected carrier mothers during passage through the birth canal. Copyright (c) 2021, Taiwan Pediatric Association. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/ by-nc-nd/4.0/).