Project description:Cefiderocol (CFDC) is a novel chlorocatechol-substituted siderophore approved to treat complicated urinary tract infections and for hospital-acquired and ventilator-acquired pneumonia. In previous work, human fluids, were shown to increase the minimum inhibitory concentration (MICs) of Acinetobacter baumannii against CFDC and reduce the expression of genes related to iron uptake systems, which could explain the need for higher concentrations of CFDC to exert inhibitory action. Herein, we analyzed the impact of human urine (HU), which contains low albumin concentrations, on the expression of iron-uptake related genes and MIC values of two carbapenem-resistant A. baumannii. Levels of resistance to CFDC were not modified by HU in strain AMA40 but were reduced in the case of strain AB5075. Testing other carbapenem-resistant A. baumannii isolates showed that the CFDC MICs were unmodified or reduced in the presence of HU. The expression of piuA, pirA, bauA, and bfnH determined by qRT-PCR was enhanced in both strains when HU was present in the culture medium. All four tested genes are involved in recognizing ferric siderophore complexes or internalization into the cell’s cytosol. In contrast, the effect of HU on genes associated with resistance to β-lactams, antibiotics commonly used to treat urinary tract infections caused by A. baumannii, was variable; the transcriptional analysis of pbp1, pbp3, blaOXA-51-like, blaADC, and blaNDM-1 showed significant variation. In summary, HU, probably due to the albumin and free iron content, does not adversely impact or slightly improves the activity of CFDC when tested against A. baumannii in urine in contrast to other human bodily fluids.
Project description:A major reservoir for spread of the emerging pathogen Acinetobacter baumannii is hopsital surfaces, where bacteria persist in a desiccated state. To identify gene products influencing desiccation survival, a transposon sequencing (Tn-seq) screen was performed. Using this approach, we identified genes both positively and negatively impacting the desiccation tolerance of A. baumannii.
Project description:Desiccation tolerance has been implicated as an important characteristic that potentiates the spread of the bacterial pathogen Acinetobacter baumannii through hospitals on dry surfaces. Despite the potential importance of this stress response, scarce information is available describing the underlying mechanisms of A. baumannii desiccation tolerance. Here we characterize the factors influencing desiccation survival of A. baumannii. At the macroscale level, we find that desiccation tolerance is influenced by cell density, growth phase, and desiccation medium. Our transcriptome analysis indicates that desiccation represents a unique state for A. baumannii compared to commonly studied growth conditions and strongly influences pathways responsible for proteostasis. Remarkably, we find that an increase in total cellular protein aggregates, which is often considered deleterious, correlates positively with the ability of A. baumannii to survive desiccation. We show that artificially inducing protein aggregate formation increases desiccation survival, and more importantly, that proteins incorporated into cellular aggregates can retain activity. Our results suggest that protein aggregates may promote desiccation tolerance in A. baumannii through preserving and protecting proteins from damage during desiccation until rehydration occurs.
Project description:We performed RNAseq for gene expression analysis for six strains of Acinetobacter Baumannii isolated from blood samples (defined as strains 1, 2, 3, 4 and 6) of patients hospitalized at the University Hospital \\"San Giovanni di Dio e Ruggi d'Aragona\\" (Salerno, Italy)
Project description:The goal of this RNA-Seq study was to determine Acinetobacter baumannii's transcriptiional response to sub-MIC concentrations of benzalkonium chloride in Acinetobacter baumannii. This RNA-seq data was then utilized to aide in the determination of the sub-MIC mechanism of action for benzalkonium chloride.
