Intestinal Dominance by and among Neonates in the Setting of an Outbreak.

(1) Background: We determined the relevance of intestinal dominance by spp. during a neonatal outbreak over 13 weeks. (2) Methods: Rectal swabs (n = 110) were obtained from 42 neonates. spp. was cultured from swabs obtained from 13 neonates (Group 1), while the other 29 neonates were culture-negative (Group 2). Total DNA was extracted from rectal swabs, and quantitative PCRs (qPCRs) using - and -gene-specific primers were performed. relative intestinal loads (RLs) were determined using ΔΔC. Clonality was investigated by random amplified polymorphic DNA analysis and whole-genome sequencing. (3) Results: The outbreak was caused by during the first eight weeks and during the remaining five weeks. spp. were detected by qPCR in all Group 1 neonates and eleven Group 2 neonates. RLs of spp. were higher in Group 1 as compared to Group 2 (6.31% vs. 0.09%, < 0.05) and in the first swab compared to the last (26.9% vs. 4.37%, < 0.05). Nine neonates had extraintestinal detection of spp.; eight of them were infected. RLs of the patients with extraintestinal spread were higher than the rest (2.79% vs. 0.29%, < 0.05). (4) Conclusions: Intestinal dominance by spp. plays a role in outbreaks and extraintestinal spread.