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Objective: The treatment of Achromobacter xylosoxidans bacteremia is challenged by antimicrobial resistance and the paucity of data. We aimed at offering a contemporary description of this uncommon entity., Methods: Retrospective case series of 13 episodes of A. xylosoxidans bacteremia diagnosed over a 10-year period (November 2007 to May 2017) in our tertiary care center., Results: Solid organ cancer and heart failure were the most common comorbidities (4/13 [30.7%]). All but one episodes were hospital-acquired. Most patients had received previous antibiotic therapy (7/13 [53.8%]) and had a central venous catheter in place (6/13 [46.1%]). Primary and intravascular catheter were the most common sources (4/13 [30.7%] each). Meropenem was the agent with best in vitro activity (92.3% [12/13] of susceptible isolates). All-cause 30-day mortality (overall 23.1%) was higher in patients with primary bacteremia (50.0% vs. 11.1%; P-value=0.203) and prior chemotherapy (66.7% vs. 10.0%; P-value=0.108)., Conclusions: Bacteremia due to A. xylosoxidans constitutes a serious infection among immunocompromised hosts. Carbapenem-based therapy may be appropriate in most cases., (©The Author 2018. Published by Sociedad Española de Quimioterapia. This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)(https://creativecommons.org/licenses/by-nc/4.0/).)

Objectives: Limited data exist regarding the role of agr dysfunction in reducing susceptibility to vancomycin in methicillin-susceptible Staphylococcus aureus (MSSA). This study investigated the clinical and molecular epidemiology of MSSA causing bacteraemia, with emphasis on the reduced susceptibility to vancomycin (RSV) phenotype (MIC ≥ 1.5 mg/L) and its relationship with agr dysfunction., Methods: All MSSA bloodstream isolates obtained at our hospital during 2010 were analysed. Antimicrobial susceptibility was determined and time-kill experiments were performed for oxacillin. Multilocus sequence type and agr genotype were determined and DNA microarray analysis of virulence factors was performed. agr dysfunction was assessed phenotypically and by RT-PCR quantification of RNAIII., Results: Of 84 MSSA, 55 (65.5%) exhibited the RSV phenotype, comprising 13 clonal complexes. agr II polymorphism was more prevalent in RSV than non-RSV isolates (41.8% versus 17.2%, P = 0.023) and average levels of RNAIII gene expression were higher in RSV than non-RSV isolates (ΔCt 4.05 ± 3.29 versus 1.5 ± 2.11, P = 0.005), implying greater agr dysfunction in RSV MSSA., Conclusions: We demonstrated a correlation between RSV phenotype in MSSA and reduced agr expression, particularly in association with the agr II genotype. These results may help to understand the role of agr dysfunction in the increased mortality in MSSA infections.