Project description:Here we investigated colistin effects on A. baumannii, employing a Mass spectrometry approach and comparing a colistin-susceptible multidrug-resistantclinical isolate to its colistin-dependent subpopulation obtained by subsequent passages in moderate colistin concentrations. Colistin dependence might represent a stepping-stone to resistance, but the mechanisms of colistin dependence are far from clear.
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:RNA sequencing transcriptomics was performed on a highly multidrug resistant A. baumannii strain belonging to international clone I, AB5075_UW and a transposon insertion inactivated mutant of ABUW_1103 (DesT1), which encodes for a TetR family regulator. Transcriptomics revealed that DesT1 might function as a global regulator controlling expression of various genes involved in fatty acid metabolism and transport and a range of outer membrane proteins. Genes encoding acyl-CoA desaturase and ferredoxin reductase were found to be significantly upregulated when DesT1 regulator was inactivated. Aerobic desaturases are known to play an important role in maintaining membrane homeostasis.
Project description:RNA sequencing transcriptomics was performed on a highly multidrug resistant A. baumannii strain belonging to international clone I, AB5075_UW and a transposon insertion inactivated mutant of ABUW_0182 (acmS), which encodes a hybrid histidine kinase.Transcriptomics suggests that AcmS controls expression of the genes involved in short-chain fatty acid metabolism in A. baumannii. Biophysical analyses showed ABUW_0182 binds acetic and propionic acid with affinities in a low micromolar range, suggesting they represent the physiological ligands for this hybrid histidine kinase system.
Project description:Tigecycline, a protein translation inhibitor, is a treatment of last resort for infections caused by the opportunistic multidrug resistant human pathogen Acinetobacter baumannii. However, strains resistant to tigecycline were reported not long after its clinical introduction. Translation inhibitor antibiotics perturb ribosome function and induce the reduction of (p)ppGpp, an alarmone involved in the stringent response that negatively modulates ribosome production. Through RNA sequencing, this study revealed a significant reduction in the transcription of genes in citric acid cycle and cell respiration, suggesting tigecycline inhibits or slows down bacterial growth. Our results indicated that the drug-induced reduction of (p)ppGpp level promoted the production but diminished the degradation of ribosomes, which mitigates the translational inhibition effect by tigecycline. The reduction of (p)ppGpp also led to a decrease of transcription coupled nucleotide excision repair which likely increases the chances of development of tigecycline resistant mutants. Increased expression of genes linked to horizontal gene transfer were also observed. The most upregulated gene, rtcB, involving in RNA repair, is either a direct tigecycline stress response or is in response to the transcription de-repression of a toxin-antitoxin system. The most down-regulated genes encode two b-lactamases, which is a possible by-product of tigecycline-induced reduction in transcription of genes associated with peptidoglycan biogenesis. This transcriptomics study provides a global genetic view of why A. baumannii is able to rapidly develop tigecycline resistance.
Project description:RNA sequencing transcriptomics was performed on a highly multidrug resistant A. baumannii strain belonging to international clone I, AB5075_UW and a transposon insertion inactivated mutant of ABUW_1016 (cbl), which encodes a LysR-type transcriptional regulator.Transcriptomics suggests that Cbl controls expression of the genes involved in acquisition and reduction of various sulfur sources in A. baumannii.
