Unveiling spp. in the Neonatal Intensive Care Unit: Clinical Impacts and Antibiotic Resistance.

spp., opportunistic Gram-negative bacilli, pose increasing risks for nosocomial infections, particularly in neonatal intensive care units (NICUs). This study investigates an outbreak caused by in an NICU during the COVID-19 pandemic, examining colonization and infection risk factors, clinical outcomes, and antibiotic resistance. : A retrospective analysis was conducted on neonates hospitalized in a tertiary NICU from 2020 to 2021. Colonization and infection were identified via microbiological testing of clinical samples. Risk factors, such as mechanical ventilation, vascular access, mode of feeding, and antibiotic use, were recorded. Environmental sampling identified potential contamination sources. Antibiotic susceptibility was determined using EUCAST PK/PD breakpoints. : Among 36 neonates affected, 31 were colonized, and 5 developed infections, including bloodstream infection, pneumonia, surgical site infection, and urinary tract infection. Environmental investigations revealed contaminated water heaters as the primary sources. All isolates showed resistance to carbapenems and aminoglycosides but retained susceptibility to trimethoprim-sulfamethoxazole. The vast majority were susceptible to fluoroquinolones. : This outbreak underscores the role of environmental water reservoirs, invasive procedures, and broad-spectrum antibiotics in colonization and infection. Biofilm formation and antibiotic resistance complicate eradication and treatment. Heightened surveillance, rigorous infection control, and antimicrobial stewardship are crucial for mitigating risks in NICU settings.