Immediate Postnatal Microbial Colonization in Sick Term Neonates Admitted to NICU: Prevalence, Microbiota, and Associated Characteristics.

Objective: The immediate postnatal rectal (RC) and nasopharyngeal colonization (NPC), their prevalence, taxa, and associated characteristics were investigated in sick term infants admitted to the neonatal intensive care unit.

Study Design: In a retrospective cohort single center study, nasopharyngeal (NPCx) and rectal (RCx) microbial cultures were obtained within 20 minutes of birth in mild-to- moderate sick term infants. Associations between the colonization and maternal-neonatal variables, including early neonatal course, were analyzed via logistic regression analysis.

Results: A total of 154 term infants were admitted for respiratory distress, hypoglycemia, maternal chorioamnionitis (CHO), and suspected neonatal sepsis; out of which, 80 (52%) were NPCx-positive (+) infants. The duration of rupture of membrane (ROM) was higher (15.5 ± 10.0 vs. 11.3 ± 11.0 hours,  = 0.02), while the respiratory support requirement (16.3 vs. 29.7%,  = 0.04) and occurrence of maternal group B (GBS) colonization lower (15.0 vs. 35.1%,  = 0.01) in NPCx+ infants. ROM increased (odds ratio [OR]: 1.04, 95% confidence interval [CI]: 1.01-1.07), and maternal GBS colonization decreased the odds of positive nasopharyngeal cultures (OR: 0.31, 95% CI: 0.14-0.72). The major microorganisms isolated were (41%), α hemolytic (AHS; 16%), (13%), and GBS (1.06%). Among the enrolled infants, 44 (28.5%) were RCx positive. The need for (11.4 vs. 27.3%,  = 0.03) and days on respiratory support (0.2 ± 0.6 vs. 0.8 ± 2.5,  = 0.03) were lower and the occurrence of CHO higher (41.0 vs. 23.2%,  = 0.04) in the RCx positive infants. Cesarean section (CS) was performed less frequently (18.2 vs. 55.5%,  = 0.001) and decreased the odds of having positive rectal cultures (OR: 0.21, 95% CI: 0.08-0.51). In total, 80% of the RCx positive infants isolated , and 6.8% Klebsiella.

Conclusion: In sick term neonates, early NPC is dominated by SE and RC by . NPC is supported by ROM and declines by maternal GBS colonization, whereas RC decreases with CS. NPC is more common than RC in this population.

Key Points: · Early neonatal nasopharyngeal microbial colonization in sick term neonates, dominated by Staphylococcus epidermidis, is enhanced by the rupture of membrane and diminishes by maternal GBS colonization.. · Cesarean section decreases the rectal colonization, which is composed of E. coli as the predominant microorganism.. · The microbiota of early postnatal colonization in sick term neonates differs from that reported in healthy term infants..