Project description:Antibiotic resistance associated with the expression of the clinically significant carbapenemases, IMP, KPC, and NDM and OXA-48 in Enterobacteriaceae is emerging as a worldwide calamity to health care. In Australia, IMP-producing Enterobacteriaceae is the most prevalent carbapenemase-producing Enterobacteriaceae (CPE). Genomic characteristics of such carbapenemase-producing Enterobacteriaceae (CPE) are well described, but the corresponding proteome is poorly characterised. We have thus developed a method to analyse dynamic changes in the proteome of CPE under antibiotic pressure. Specifically, we have investigated the effect of meropenem at sub-lethal concentrations to develop a better understanding of how antibiotic pressure leads to resistance. Escherichia coli, producing either NDM, IMP or KPC type carbapenemase were included in this study, and their proteomes were analysed in growth conditions with or without meropenem.
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:The study aimed to characterize plasmids mediating carbepenem resistance in Klebsiella pneumoniae in Pretoria, South Africa. We analysed 56 K. pneumoniae isolates collected from academic hospital around Pretoria. Based on phenotypic and molecular results of these isolates, 6 representative isolates were chosen for further analysis using long reads sequencing platform. We observed multidrug resistant phenotype in all these isolates, including resistance to aminoglycosides, tetracycline, phenicol, fosfomycin, floroquinolones, and beta-lactams antibiotics. The blaOXA-48/181 and blaNDM-1/7 were manily the plasmid-mediated carbapenemases responsible for carbapenem resistance in the K. pneumoniae isolates in these academic hospitals. These carbapenemase genes were mainly associated with plasmid replicon groups IncF, IncL/M, IncA/C, and IncX3. This study showed plasmid-mediated carbapenemase spread of blaOXA and blaNDM genes mediated by conjugative plasmids in Pretoria hospitals.
2019-10-17 | GSE138949 | GEO
Project description:OXA-48 carbapenemase-producing Salmonella enterica serovar Kentucky sequence type 198 isolated from Saudi Arabia
Project description:Gene expression profiles of two Pseudomonas aeruginosa taxonomic outlier clinical isolates, CLJ1 and CLJ3 [CLJ3] Pseudomonas aeruginosa taxonomic outliers emerged recently as infectious for humans, provoking hemorrhagic pneumonia. Those bacteria lack classical type III secretion system, and utilize the pore-forming toxin for infection. Two clones CLJ1 and CLJ3 belonging to these taxonomic outliers have been isolated from the same patient at two different times during hospitalization. P. aeruginosa CLJ3 displays antibiotic resistance phenotype, while CLJ1 is more cytotoxic on epithelial and endothelial cells.
Project description:Gene expression profiles of two Pseudomonas aeruginosa taxonomic outlier clinical isolates, CLJ1 and CLJ3 [CLJ1] Pseudomonas aeruginosa taxonomic outliers emerged recently as infectious for humans, provoking hemorrhagic pneumonia. Those bacteria lack classical type III secretion system, and utilize the pore-forming toxin for infection. Two clones CLJ1 and CLJ3 belonging to these taxonomic outliers have been isolated from the same patient at two different times during hospitalization. P. aeruginosa CLJ3 displays antibiotic resistance phenotype, while CLJ1 is more cytotoxic on epithelial and endothelial cells.
Project description:In the Pseudomonas aeruginosa type strain PA14, 40 genes are known to encode for diguanylate cyclases (DGCs) and/or phosphodiesterases (PDEs), which modulate the intracellular pool of the nucleotide second messenger c-di-GMP. While in general, high levels of c-di-GMP drive the switch from highly motile phenotypes towards a sessile lifestyle, the different c-di-GMP modulating enzymes are responsible for smaller and in parts non-overlapping phenotypes. In this study, we sought to utilize previously recorded P. aeruginosa gene expression datasets on 414 clinical isolates to uncover transcriptional changes as a result of a high expression of genes encoding diguanylate cyclases. We demonstrate that the selection of sub-groups of clinical isolates with high versus low expression of regulatory genes served the identification of their downstream regulons. Thus, analyzing transcriptional profiles of clinical isolates with variant expression of diguanylate cyclase genes might provide a unique opportunity to bypass the problem that for many c-di-GMP modulating enzymes it is not known under which conditions their expression is activated. However, because the high c-di-GMP associated phenotypes were rapidly lost in the clinical isolates, we were unable to confirm diguanylate specific gene regulation. It is possible that the elevated c-di-GMP concentrations observed in the clinical P. aeruginosa isolates were due to a memory response, in which the bacteria maintain a certain level of c-di-GMP even after being removed from the conditions that induced the production of c-di-GMP. Further studies would be needed to determine the specific mechanisms underlying this memory response in P. aeruginosa.
Project description:The Pseudomonas aeruginosa PAO1 gene phaF (PA5060) is a transcriptional regulator in the closely related pseudomonad P. putida. phaF is expressed at higher levels in P. aeruginosa clinical isolates from the cystic fibrosis respiratory tract. To determine the role of phaF in regulating P. aeruginosa gene expression, we cloned it under control of the pBAD promoter in expression vector pJN105 and compared expression in this strain relative to an empty vector control strain. We used microarrays to study overall gene expression in a P. aeruginosa PAO1 phaF overexpression strain.