Exploratory Hemodynamic and Hematologic Trajectories by Culture Status Among Neonates Evaluated for Infection

Background: Neonates evaluated for infection undergo rapid physiologic transition, making isolated measurements difficult to interpret. Because a positive culture field does not by itself establish clinical sepsis, we explored whether physiologic and laboratory trajectories differed by recorded culture status during the first three postnatal days. Methods: This single-center prospective observational longitudinal study included 65 neonates with linked measurements on days 1, 2, and 3. The exposure was a binary culture field in the source database; specimen source, organism identity, and pathogen-versus-contaminant adjudication were unavailable. Group-specific medians were summarized, and gestational-age-adjusted linear models with patient-clustered robust standard errors tested culture status, time, and culture-status-by-time effects. Results: The cohort included 26 culture-positive and 39 culture-negative neonates. On day 1, the culture-positive group had lower median systolic blood pressure (48.5 vs. 57.0 mmHg), diastolic blood pressure (24.5 vs. 33.0 mmHg), and MAP (31.0 vs. 41.0 mmHg), more negative base excess (−7.65 vs. −3.60 mmol/L), and lower platelet counts (219 vs. 282 × 109/L). Diastolic pressure rose in both groups and converged by day 3; the adjusted culture-status-by-time interaction was significant (p = 0.012). MAP increased over time, but its interaction was not significant (p = 0.244). Culture-positive status was associated with a lower day-1 platelet count (adjusted beta, −73.0 × 109/L; 95% CI, −128.1 to −17.8; p = 0.010), without evidence of a differential platelet trajectory (interaction p = 0.623). CRP was retained as a descriptive outcome only because of lower-limit censoring. Conclusions: Recorded culture status was associated with selected early hemodynamic, metabolic, and hematologic differences in this small exploratory cohort. These associations cannot be considered sepsis-specific and require confirmation after clinical culture adjudication, standardized timestamping and blood-pressure measurement, inclusion of fatal cases, and adjustment for illness severity and treatment exposures.