Project description:Acinetobacter baumannii is a major cause of nosocomial infections which can survive in different hospital environments and its multidrug-resistant capacity is major concern now-a-days. ppGpp dependent stringent response mediates reprogramming of gene expression with diverse function in many bacteria. A baumannii A1S_0579 gene is responsible for ppGpp production. Transcriptome analysis of early stationary phase cultures represents several differentially expressed genes in ppGpp deficient strain (∆A1S_0579). We found that the expression of csu operon, which is important in pili biosynthesis for early biofilm formation, was significantly reduced in the ppGpp-deficient strain. Our findings showed that ppGpp signaling plays critical role in biofilm formation, surface motility, adherence and virulence of A baumannii. This study is the first demonstration of the association between ppGpp and pathogenicity of A. baumannii.
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: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:Hospital environments serve as excellent reservoirs for the opportunistic pathogen Acinetobacter baumannii in part because it is exceptionally tolerant to desiccation. To understand the functional basis this trait, we used transposon sequencing (Tn-seq) to identify genes contributing to desiccation tolerance in A. baumannii strain AB5075. We identified 142 candidate desiccation tolerance genes, one of which encoded the global post-transcriptional regulator CsrA. We characterized CsrA in more detail by using proteomics to identify proteins that were differentially present in wild type and csrA mutant cells. Among these were a predicted universal stress protein A, an iron-containing redox protein, a KGG-domain containing protein, and catalase. Subsequent mutant analysis showed that each of these proteins was required for A. baumannii desiccation tolerance. The amino acid sequence of the KGG-domain containing protein predicts that it is an intrinsically disordered protein. Such proteins are critical for desiccation tolerance of the small animals called tardigrades. This protein also has a repeat nucleic acid binding amino acid motif, suggesting that it may protect A. baumannii DNA from desiccation-induced damage.
Project description:Successful termination of an intermittent outbreak caused by an emerging pandrug-resistant Acinetobacter baumannii clone ST457 in a tertiary hospital
Project description:The experiment contains native Tn-seq data for Acinetobacter baumannii strain AB5075 with different genetic alterations. The strain was grown at 37 degrees in LB medium and genomic DNA was isolated. We then used PCR to select for DNA regions containing a junction between ISAba13 and chromosomal DNA. Libraries were then prepared using these DNA fragments.
Project description:We report transcriptome sequencing analysis on A. baumannii strain ATCC 17978 cultures treated with or without meropnem at 0.5, 3 and 9 h, in triplicate.
Project description:The experiment contains ChIP-seq data for Acinetobacter baumannii strain AB5075 encoding 3xFLAG tagged H-NS. Experiments were done with or without ectopic expression of the truncated H-NS-39 protein (corresponding to the H-NS multimerization surface). The strain was grown at 37 degrees in LB medium and crosslinked with 1 % (v/v) formaldehyde. After sonication, to break open cells and fragment DNA, immunoprecipitations were done using anti-FLAG antibodies against. Libraries were prepared using DNA remaining after immunoprecipitation.