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:The antibiotic resistance of A. baumannii has been increasing in recent years. There are still many questions unclear concerning the mechanism of tigecycline resistance in A. baumannii. iTRAQ based proteomic analysis were used to reveal the mechanism of tigecycline resistance in Acinetobacter baumannii.
Project description:The mechanism of tigecycline resistance in Acinetobacter baumannii under sub-minimal inhibitory concentration tigecycline by comparative protemics
Project description:We have shown recently that in the human pathogen Acinetobacter baumannii, light is able to modulate key aspects contributing to its success as a pathogen such as motility, biofilm formation and virulence in a way that depends on the BLUF photoreceptor BlsA at 24ºC. In addition, light can induce reduction in susceptibility to certain antibiotics such as minocycline and tigecycline in a photoreceptor-independent manner, directly inducing expression of resistance genes. In this work, we performed RNAseq studies to identify new traits modulated by light in this pathogen in A. baumannii strain ATCC 19606. We have found 226 differentially expressed genes between light and dark, which comprise not only important determinants related to pathogenicity/resistance, but also to the bacteria´s survival in the environment.
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: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.
