Neonatal Intensive Care Unit Outbreak of Ralstonia pickettii Bacteremia Associated with Contaminated Sterile Distilled Water: Clinical, Environmental, and Molecular Epidemiological Investigation.

Ralstonia pickettii is an opportunistic Gram-negative bacterium associated with healthcare-associated infections, particularly in premature infants and other immunocompromised or critically ill patients. This study aimed to investigate a neonatal intensive care unit outbreak of Ralstonia pickettii bacteremia by describing the clinical characteristics of affected infants, identifying the environmental source, and evaluating the genetic relatedness between clinical and environmental isolates. Hospital records from January 2023 through November 2025 were reviewed; the nine included cases occurred between February 2024 and October 2025. Demographic, clinical, and laboratory data were reviewed. Environmental sampling was performed to identify the source of contamination. Genetic relatedness between clinical and environmental isolates was evaluated using arbitrarily primed polymerase chain reaction (AP-PCR), and the molecular findings were interpreted together with microbiological and epidemiological data. This study was initially designed as a retrospective clinical review and was subsequently expanded to include an outbreak investigation after three temporally clustered cases were identified in October 2025. The outbreak involved nine neonates with Ralstonia pickettii bacteremia. Environmental investigation identified Ralstonia pickettii in both opened and unopened sterile distilled water samples. Clinical and environmental isolates demonstrated highly similar AP-PCR banding patterns, supporting genetic relatedness when interpreted together with microbiological and epidemiological findings. Following removal of the contaminated source and implementation of infection control measures, no additional R. pickettii bacteremia cases were identified. Overall mortality was 44.4%, whereas only one death (11.1%) was considered attributable to Ralstonia pickettii bacteremia. Ralstonia pickettii can cause healthcare-associated outbreaks in neonatal intensive care units. Integration of microbiological, environmental, epidemiological, and molecular findings may facilitate timely outbreak source identification and implementation of effective infection control measures.