Hospital outbreak sustained by Klebsiella pneumoniae sequence type 147 co-producing NDM-1 and OXA-48, Rome, Italy, February to March 2025: molecular tracing and control measures

We describe an outbreak of carbapenemase-producing <i>Klebsiella pneumoniae</i> that occurred in February-March 2025 in a tertiary care hospital in Rome, Italy. Ten patients in two adjacent critical care units were found colonised or infected with strains co-producing NDM-1 and OXA-48 carbapenemases. Nine of these had acquired infections in our hospital and were detected through routine or enhanced rectal swab screening. Rapid implementation of infection prevention and control (IPC) measures, including patient cohorting, environmental cleaning and contact surveillance, helped contain transmission. Despite these measures, the outbreak spread across wards, suggesting challenges in timely isolation, patient movement within hospitals and contact precautions in intensive care units. Environmental sampling revealed a single surface contaminated with the outbreak strain. Rapid molecular typing using an in-house nanopore sequencing protocol (NanoTyping), supported by whole genome sequencing, confirmed clonal spread of the high-risk ST147 clone. Phylogenetic comparison with Italian isolates from previous outbreaks indicated regional dissemination of this clone. This outbreak highlights the need to combine genomic surveillance and rapid diagnostics to support real-time response. In settings with high multidrug-resistant organism (MDRO) prevalence, enhanced screening, routine surveillance and rigorous IPC protocols remain critical to prevent and control the spread of emerging high-risk clones in healthcare facilities.