Project description:We analyzed the extracellular proteome of colistin-resistant Korean Acinetobacter baumannii (KAB) strains to identify proteome profiles that can be used to characterize extensively drug-resistant KAB strains.
Project description:Purpose: The goal of this study was to elucidate the collateral effects associated with OXA-23 overexpression on the Acinetobacter baumannii global transcriptome. Results: Besides the 99.73-fold increase in blaOXA-23 transcript upon IPTG induction, no other transcripts showed more than a 2-fold change compared to the wildtype control. This suggests that OXA-23 over expression to levels similarly observed in multi drug resistant A. baumannii clinical isolates does not effect the transcriptome.
Project description:The bacterial pathogen, Acinetobacter baumannii, is a leading cause of drug-resistant infections. Here, we investigated the potential of developing nanobodies that specifically recognize A. baumannii over other Gram-negative bacteria. Through generation and panning of a synthetic nanobody library, we identified several potential lead candidates. We demonstrate how incorporation of next generation sequencing analysis can aid in selection of lead candidates for further characterization. Using monoclonal phage display, we validated the binding of several lead nanobodies to A. baumannii. Subsequent purification and biochemical characterization revealed one particularly robust nanobody that broadly and specifically bound A. baumannii compared to other common drug resistant pathogens. These findings support the potentially for nanobodies to selectively target A. baumannii and the identification of lead candidates for possible future diagnostic and therapeutic development.
Project description:Acinetobacter baumannii is a Gram-negative opportunistic pathogen that causes multiple infections, including pneumonia, bacteremia, and wound infections. Due to multiple intrinsic and acquired drug-resistance mechanisms, A. baumannii isolates are commonly multi-drug resistant and infections are notoriously difficult to treat. Therefore, it is important to identify mechanisms used by A. baumannii to survive stresses encountered during infection as a means of identifying new drug targets. In this study, we determined the transcriptional response of A. baumannii to hydrogen peroxide stress using RNASequencing. Upon exposure to hydrogen peroxide, A. baumannii differentially transcribes several hundred genes. In this study, we also determined the transcriptional profile of A. baumannii strains with the transcriptional regulators mumR or oxyR genetically inactivated and identified transcriptional differences between these strains and wild-type A. baumannii in response to hydrogen peroxide stress. In doing this, the function of A. baumannii OxyR in hydrogen peroxide stress resistance and regulation of genes required for hydrogen peroxide detoxification was defined. Moreover, the contribution of the uncharacterized regulator MumR to hydrogen peroxide stress resistance was also explored. This work reveals the transcriptome of an important human pathogen in the presence of hydrogen peroxide stress.
Project description:Colistin is a crucial last-line drug used for the treatment of life-threatening infections caused by multi-drug resistant strains of the Gram-negative bacteria, Acinetobacter baumannii. However, colistin resistant A. baumannii isolates can be isolated following failed colistin therapy. Resistance is most often mediated by the addition of phosphoethanolamine (pEtN) to lipid A by PmrC, following missense mutations in the pmrCAB operon encoding PmrC and the two-component signal transduction system PmrA/PmrB. We recovered an isogenic pair of A. baumannii isolates from a single patient before (6009-1) and after (6009-2) failed colistin treatment that displayed low/intermediate and high levels of colistin resistance, respectively. To understand how increased colistin-resistance arose, we genome sequenced each isolate which revealed that 6009-2 had an extra copy of the insertion sequence element ISAba125 within a gene encoding an H-NS-family transcriptional regulator. Consequently, transcriptomic analysis of the clinical isolates identified was performed and more than 150 genes as differentially expressed in the colistin-resistant, hns mutant, 6009-2. Importantly, the expression of eptA, encoding a second lipid A-specific pEtN transferase, but not pmrC, was significantly increased in the hns mutant. This is the first time an H-NS-family transcriptional regulator has been associated with a pEtN transferase and colistin resistance.
Project description:Objectives: Colistin remains a last-line treatment for multidrug-resistant Acinetobacter baumannii and combined use of colistin and carbapenems has shown synergistic effects against multidrug-resistant strains. In order to understand the bacterial responses to these antibiotics we analysed the transcriptome of A. baumannii following exposure to each.
Project description:Using Nanopore sequencing, our study has revealed a close correlation between genomic methylation levels and antibiotic resistance rates in Acinetobacter Baumannii. Specifically, the combined genome-wide DNA methylome and transcriptome analysis revealed the first epigenetic-based antibiotic-resistance mechanism in A. baumannii. Our findings suggest that the precise location of methylation sites along the chromosome could provide new diagnostic markers and drug targets to improve the management of multidrug-resistant A. baumannii infections.
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)