BACKGROUND: Carbapenemase-producing Pseudomonas aeruginosa (CPPA) is known to cause outbreaks in healthcare settings. Outbreak investigations, including screening of contact patients and the environment, are key in infection prevention and control (IPC) management to contain them. AIM: The aim of this study was to determine the yield of outbreak investigations performed after unexpected detections of CPPA in clinical or screening cultures of patients hospitalized on a general ward. METHODS: In this retrospective cohort study, we included all adult patients newly detected with CPPA ('index patients') while hospitalized on a general ward from June 2011 to December 2021. We evaluated the outbreak investigations performed, i.e., screening of epidemiologically linked patients ('contact patients') and the environment. Isolates were analysed by whole-genome sequencing (WGS). FINDINGS: Outbreak investigations of 34 of 38 (89.5%) index patients were evaluated, with screening of contact patients performed in 34 (100%) and the environment in 18 (52.9%). CPPA was detected in eight (44.4%) of the environmental screenings, and WGS confirmed relatedness to the index in four (22.2%). A total of 1707 of 1982 (86.1%) identified contact patients were screened, of which eight carried CPPA (0.5%). WGS confirmed transmission from index patient to contact patient in five of these (0.3%). CONCLUSION: Environmental screening should be part of outbreak investigations for CPPA, as it identifies sources which enables timely installation of targeted IPC measures. Identification of index-to-contact patient transmission was rare in our setting, thus implying reconsideration of the definition of contact patients at high risk is needed.