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Objectives: We described the molecular characterization of an Enterobacter cloacae strain resistant to cefiderocol, co-harbouring bla IMP-19 and mcr-4.3 resistance genes METHODS: The strain was isolated from the rectal swab of a 77-year-old woman during the screening for the detection of patients colonized by carbapenemase-producing Enterobacterales (CPE), in Bologna (Italy). The strain was identified at the species level by MALDI-TOF mass spectrometry and the presence of IMP carbapenemase was confirmed both by a phenotypic immunochromatographic method, and by a rapid commercial NAAT. The strain underwent an antimicrobial susceptibility testing and its genome was fully characterized to assess (i) the Multi Locus Sequence Type (MLST), (ii) the presence of antimicrobial resistance genes (AMR), (iii) the presence of virulence genes coupled with Mobile Genetic Elements., Results: MLST identified the strain as ST837. A plasmid of 60'691 bp, very similar to MW574937 plasmid of Escherichia coli was identified and carried the following AMR genes: aac(6')-II,bla BEL-1 , bla IMP-19 , msr(E), mph(E), sul1. This plasmid harboured several tra gene (traB, traC, traD, traG, traI, traJ, traKtraL, traM) of the transfer operon of E. coli conjugative F plasmid. Other AMR genes were located in the chromosome (bla CMH-3 and fosA) or in other plasmids (bla SHV-12 and mcr-4.3). In vitro the strain showed resistance to many beta-lactams, including cefiderocol, whereas, despite the presence of mcr-4.3 gene, it was susceptible to colistin., Conclusions: Further studies are needed to better evaluate the origin of this strain, monitoring the presence of gram-negative bacilli with a similar molecular structure in our area., Competing Interests: Declaration of competing interest None declared., (Copyright © 2025. Published by Elsevier Ltd.)

Objectives: Infections by carbapenem-resistant Enterobacterales (CRE) in hospitals represent a severe threat but little is known on outbreaks in rehabilitation wards caused by Klebsiella pneumoniae producing Klebsiella pneumoniae Carbapenemase (KPC-Kp). We report an outbreak by KPC-Kp, in a neurorehabilitation unit in Italy, analysed through whole-genome sequencing (WGS) for transmission routes reconstruction to improve management of KPC-Kp infections in rehabilitation units., Methods: We investigated cases and KPC-Kp isolates collected from February to October 2022 from hospital surveillance. Carbapenem resistance was identified with disk diffusion and minimum inhibitory concentration tests, carbapenemase production through immunochromatographic lateral flow assays. All isolates were genotyped through WGS to highlight possible phylogenetic relationships. The most likely transmission networks of KPC-Kp were reconstructed with Bayesian discrete-time stochastic models., Results: Nineteen patients were colonized by KPC-Kp. Two isolates belonged to sporadic sequence types (STs; ST348 and ST219) whereas 9 of 19 and 8 of 19 isolates belonged to ST307 and ST716, respectively. Among the ST307 isolates, we identified two genomically distinct clusters of five and two cases. All ST716 isolates were highly similar. Genotyping and the reconstruction of transmission networks of KPC-Kp based on genomic data identified seven independent introductions into the neurorehabilitation unit rather than a single outbreak as initially hypothesized before genomic investigation. Three of the seven introductions generated chains of secondary infections, whereas the remaining four remained single cases., Conclusions: The outbreak root-causes were identified in temporary staff shortage and insufficient microbiological surveillance. Measures were adopted accordingly and the outbreak ended. The study highlights the critical role of genomic epidemiology in hospital outbreaks. © 2025 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy., (Copyright © 2025 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Salmonella is diffused worldwide, and Salmonella enterica subsp. enterica is spread worldwide with many serovars associated with the infection of domestic bovines. The most spread are S . Dublin, S . Typhimurium and S . Infantis. S. Napoli is, however very rarely reported in domestic ruminants. Here, we report an outbreak of S . Napoli on a dairy cow farm in Northern Italy (Piacenza). A total of 18 S . Napoli isolates were recovered from aborted fetuses, feces, tissues and environmental samples. Whole genome sequencing suggested that all isolates belonged to the same cluster. After the application of stringent biocontainment and biosecurity measures, no further cases were reported. However, four months after the first case, the serovar was still isolated in environmental samples, underlying the importance of adopting the correct biosecurity and biocontainment measures in order to prevent the circulation and transmission of Salmonella within the farm.