502 - Infants exposed to a short course of antibiotics for a sepsis evaluation have increased Effector T cell proportions in their peripheral blood.

Publication Number: 3483.502

Mariana Brewer, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, NEW HYDE PARK, NY, United States; Grace Fisler, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Westbury, NY, United States; Brendan M. Plotke, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Middle Island, NY, United States; Sophia Currie, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lewiston, NY, United States; Clifford S. Deutschman, Northwell Health, Manhasset, NY, United States; Matthew D. Taylor, Cohen Children's Medical Center, Manhasset, NY, United States

Background: Prolonged antibiotic exposure in infants is associated with microbial dysbiosis and altered T cell populations during the neonatal period that can continue into childhood. Our preliminary data in mice shows that even a short course of antibiotics skews T cells populations towards activation. Infants are often treated with 2-3 days of antibiotics during an evaluation for possible sepsis. We compared T cell phenotypes in newborns exposed to antibiotics to unexposed infants. Our hypothesis was that newborns treated with antibiotics for
Objective: Our objective was to evaluate whether a short course of antibiotics alters T cell phenotype in newborns.

Design/Methods: We prospectively recruited newborn infants admitted to our nursery and NICU. Chart review identified 2 groups: 1) Rule out sepsis (ROS) group - infants treated with ampicillin and gentamicin for
Results: 74 babies were included in this analysis - 35 in the control group and 39 in the ROS group (Table 1). The 2 groups were significantly different in terms of gestational age, birth weight, and sex. There was no significant difference in mode of delivery, race or ethnicity. After controlling for gestational age, the ROS group had a:
- Higher proportion of live cells that are effector memory (EM, CD45RA-, CCR7-) and CD4+ EM T cells (Fig. 1A)
- Higher proportion of CD4 T cells that are terminal effectors (TE, CD45RA+, CCR7-) (Fig. 1B)

Conclusion(s): After controlling for gestational age, infants exposed to
Table 1: Patient demographics for control and ROS groups.


Figure 1. Proportions of T cell subsets in newborn ROS compared to controls.
Peripheral blood mononuclear cells were collected from newborn ROS babies (red box plot, n=39) and controls (blue box plot, n=35) and cells were stained for flow cytometry to assess T cell subsets. Data were log-transformed for analysis. Mean - horizontal bar, standard deviation - error bars. Significance determined using linear regression, controlling for gestational age. A) Proportion of live cells made up of effector memory (EM) and CD4+ EM T cells at 1 week. B) Proportion of CD4 T cells made up of Terminal Effector (TE) T cells at 1 week.