Background: New Delhi metallo-beta-lactamase (NDM)-producing Providencia stuartii has been reported from European Union/European Economic Area (EU/EEA) countries with increasing frequency. During 2018 to 2022, 355 cases of NDM-producing P. stuartii were detected in seven hospitals reporting on NDM-production in Enterobacterales in Romania. Aim: Our aim was to determine the extent of spread of NDM-producing P. stuartii in hospitals in Romania. Methods: We analysed whole genome sequences and epidemiological data of 74 P. stuartii isolates collected in six hospitals from December 2021 to September 2023. Results: We identified four multi-hospital clusters including isolates detected over more than a year, indicating sustained spread of bla _NDM-1-carrying P. stuartii within the healthcare system. These clusters consisted of isolates from up to four hospitals and three regions. Three multi-hospital clusters were caused by a specific multidrug-resistant P. stuartii sequence type 46 lineage carrying bla _NDM-1 and a large set of additional resistance markers. Investigation in an international context showed that this lineage had already been detected in nine countries (Bulgaria, France, Germany, Ireland, the Netherlands, Romania, Switzerland, United Kingdom, United States) since 2015. Conclusion: Our results alert about the risk of carbapenem-resistant P. stuartii transmission in healthcare settings. Enhanced infection prevention and control measures should be instituted as soon as cases are detected in healthcare facilities. National surveillance systems in EU/EEA countries should, in addition to carbapenem-resistant and/or carbapenemase-producing Klebsiella pneumoniae and Escherichia coli, consider reporting carbapenem-resistant and/or carbapenemase-producing P. stuartii and other Enterobacterales where relevant.

The global escalation of severe infections due to carbapenemase-producing Enterobacterales (CPE) isolates has prompted increased usage of parenteral colistin. Considering the reported difficulties in assessing their susceptibility to colistin, the purpose of the study was to perform a comparative evaluation of six phenotypic assays—the colistin broth disc elution (CBDE), Vitek 2 Compact (bioMérieux SA, Marcy l’Etoile, France), the Micronaut MIC-Strip Colistin (Merlin Diagnostika GMBH, Bornheim-Hensel, Germany), the gradient diffusion strip Etest (bioMérieux SA, Marcy l’Etoile, France), ChromID Colistin R Agar (COLR) (bioMérieux SA, Marcy l’Etoile, France), and the Rapid Polymyxin NP Test (ELITechGroup, Signes, France)—versus the reference method of broth microdilution (BMD). All false resistance results were further assessed using population analysis profiling (PAP). Ninety-two nonrepetitive clinical CPE strains collected from two hospitals were evaluated. The BMD confirmed 36 (39.13%) isolates susceptible to colistin. According to the BMD, the Micronaut MIC-Strip Colistin, the CBDE, and the COLR medium exhibited category agreement (CA) of 100%. In comparison with the BMD, the highest very major discrepancy (VMD) was noted for Etest (n = 15), and the only false resistance results were recorded for the Rapid Polymyxin NP Test (n = 3). Only the PAP method and the Rapid Polymyxin NP Test were able to detect heteroresistant isolates (n = 2). Thus, there is an urgent need to further optimize the diagnosis strategies for colistin resistance.

Klebsiella pneumoniae is a notorious human pathogen involved in healthcare-associated infections. The worldwide expansion of infections induced by colistin-resistant and carbapenemase-producing Enterobacterales (CPE) isolates has been increasingly reported. This study aims to analyze the phenotypic and molecular profiles of 10 colistin-resistant (CR) isolates and 2 pairs of colistin-heteroresistant (ChR) (parental and the corresponding resistant mutants) isolates of K. pneumoniae CPE sourced from two hospitals. The phenotypes of strains in the selected collection had been previously characterized. Antimicrobial susceptibility testing was performed using a Vitek 2 Compact system (BioMérieux SA, Marcy l’Etoile, France), the disc diffusion method, and broth microdilution (BMD) for colistin. Whole-genome sequencing (WGS) did not uncover evidence of any mobile colistin resistance (mcr) genes, although the mgrB gene of seven isolates appeared to be disrupted by insertion sequences (ISKpn25 or ISKpn26). Possible deleterious missense mutations were found in phoP (L4F), phoQ (Q426L, L26Q, L224Q, Q317K), pmrB (R256G, P95L, T157P, V352E), and crrB (P151S) genes. The identified isolates belonged to the following clonal lineages: ST101 (n = 6), ST147 (n = 5), ST258 (n = 2), and ST307 (n = 1). All strains harbored IncF plasmids. OXA-48 producers carried IncL and IncR plasmids, while one bla_NDM-1 genome was found to harbor IncC plasmids. Ceftazidime–avibactam remains a therapeutic option for KPC-2 and OXA-48 producers. Resistance to meropenem–vaborbactam has emerged in some bla_kPC-2-carrying isolates. Our study demonstrates that the results of WGS can provide essential evidence for the surveillance of antimicrobial resistance.

Over the last decades Staphylococcus aureus (SA) has become the dominant etiology of native valve infective endocarditis, with the community-acquired methicillin-sensible Staphylococcus aureus (CA-MSSA) strains being the prevailing type. We report here a case of extremely severe CA-MSSA aortic valve acute endocarditis associated with persistent Staphylococcus aureus bacteremia (SAB) in a previously healthy man and include a literature review.The patient developed severe and rare complications (purpura, purulent pericarditis, intracerebral hematoma, and rhabdomyolysis) through systemic embolism; they required drainage of pericardial empyema and cerebral hematoma, the latter eventually caused a fatal outcome. The strains recovered from sequential blood culture sets and pericardial fluid were MSSA negative for genes encoding for staphylococcal toxic shock syndrome toxin (TSST)-1 and Panton-Valentine leukocidin. C, G, and I enterotoxin genes were detected. This case with unusually severe evolution underlines the limited ability of vancomycin to control some MSSA infections, possibly due to potential involvement of SA virulence factors, hence the importance of clinical vigilance for community SAB cases.