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 nosocomial pathogen Acinetobacter baumannii is a frequent cause of hospital acquired infections worldwide, and a challenge for treatment due to its evolved resistance to antibiotics, including carbapenems. To gain insight on A. baumannii antibiotic resistance mechanisms, we analyzed the protein interaction network of a multidrug-resistant A. baumannii clinical strain Ab5075. Using in vivo chemical cross-linking and mass spectrometry, we identified 2,068 non-redundant cross-linked peptide pairs containing 245 intra- and 398 inter- molecular interactions. Outer membrane proteins OmpA and YiaD, and carbapenemase Oxa-23 are hubs of the identified interaction network. Eighteen novel interactors of Oxa-23 were identified. Interactions of Oxa-23 with outer membrane porins OmpA and CarO were verified with co-immunoprecipitation analysis. Furthermore, transposon mutagenesis of oxa-23 or interactors of Oxa-23 demonstrated changes in meropenem or imipenem sensitivity in Ab5075. These results provide the first view of a porin-localized toxin inactivation model and increase understanding of bacterial antibiotic resistance mechanisms.
Project description:Acinetobacter baumannii is an emerging nosocomial pathogen that causes severe infections such as pneumonia or blood stream infections. As the incidence of multidrug-resistant A. baumannii infections in intensive care units increases, the pathogen is considered of greater clinical concern. Little is known about the molecular interaction of A. baumannii with its host yet. In order to study the host cell response upon A. baumannii infection, a complexome analysis was performed. For this, we identified a virulent ( A. baumannii 2778) and a non virulent (A. baumannii 1372) clinical isolate of genetic similarity > 95 % (both isolates from IC 2 harboring OXA 23). HUVECs were infected with each strain and enriched mitochondrial fraction was used for complexome profiling. Complexome analysis identified dramatic reduction of mitochondrial protein complexes in the strain of greater virulence.
Project description:Two Acinetobacter baumannii strains with low susceptibility to fosmidomycin and two reference with high susceptibility to fosmidomycin were DNA-sequenced to investigate the genomic determinants of fosmidomycin resistance.
Project description:We report the transcriptional expression from wild type, a ponA mutant, and lipooligosaccharide-deficient A. baumannii in order to understand the cellular changes after inactivation of lipid A biosynthesis. Among all strains, genes in the Localization Of Lipoprotein (Lol) transport pathway were upregulated. This study provides a framework to understand how some Acinetobacter baumannii strains can survive without lipid A and lipopolysaccharide/lipooligosaccharide.
Project description:The spread of carbapenemase-producing Enterobacterales (CPE) is emerging as a significant clinical concern in tertiary hospitals and in particular, long-term care facilities with deficiencies in infection control. This study aims to evaluate an advanced matrix-assisted laser desorption/ionization mass spectrometry (A-MALDI) method for the identification of carbapenemases and further discrimination of their subtypes in clinical isolates. The A-MALDI method was employed to detect CPE target proteins. Enhancements were made to improve detectability and mass accuracy through the optimization of MALDI-TOF settings and internal mass calibration. A total of 581 clinical isolates were analyzed, including 469 CPE isolates (388 KPC, 51 NDM, 40 OXA, and 2 GES) and 112 carbapenemase-negative isolates. Clinical evaluation of the A-MALDI demonstrated 100% accuracy and precision in identifying all the collected CPE isolates. Additionally, A-MALDI successfully discriminated individual carbapenemase subtypes (KPC-2 or KPC-3/4; OXA-48 or OXA-181 or OXA-232; GES-5 or GES-24) and also differentiated co-producing carbapenemase strains (KPC & NDM; KPC & OXA; KPC & GES; NDM & OXA), attributed to its high mass accuracy and simultaneous detection capability. A-MALDI is considered a valuable diagnostic tool for accurately identifying CPE and carbapenemase’s subtypes in clinical isolates. It may also aid in selecting appropriate antibiotics for each carbapenemase subtype. Ultimately, we expect that the A-MALDI method will contribute to preventing the spread of antibiotic resistance and improving human public health.
