Association Between Rectal Colonization of Acinetobacter baumannii and Subsequent Invasive Infections in a Neonatal Intensive Care Unit

Objective: Acinetobacter spp. is a significant nosocomial pathogen in neonatal intensive care units due to its environmental persistence and multidrug resistance profile. Rectal colonization in neonates may precede invasive infections such as bloodstream infection and ventilator-associated pneumonia, serving as a potential marker for subsequent clinical deterioration. However, the factors associated with progression from rectal colonization to systemic infection in this vulnerable population remain insufficiently defined.Materials and Methods: This retrospective cohort study was conducted between January 2018 and January 2023. Neonates with rectal Acinetobacter spp. colonization detected by surveillance cultures were included. Patients were classified according to the development of culture-confirmed bloodstream infection (BSI) and/or ventilator-associated pneumonia (VAP) during follow-up. The primary outcome was the development of invasive Acinetobacter infection after rectal colonization, and its association with recurrent colonization episodes was evaluated.Results: A total of 73 neonates with rectal Acinetobacter spp. colonization were included. During follow-up, 10 patients (13.7%) developed BSI and 5 (6.8%) developed VAP caused by Acinetobacter spp. Birth weight, gestational age, prematurity, central venous catheter use, and duration of respiratory support were comparable between groups (all p > 0.05). However, neonates who developed invasive infection had a significantly higher number of positive rectal surveillance cultures. The overall in-hospital mortality rate was 16.4%, with a higher but not statistically significant mortality observed in patients with invasive infection (30% vs. 14%, p = 0.14).Conclusion: Among neonates with rectal Acinetobacter spp. colonization, recurrent positivity in surveillance cultures appears to be associated with an increased risk of subsequent invasive infection, suggesting that persistence of colonization may serve as a practical clinical marker to identify high-risk patients who require intensified monitoring and infection control measures.