Project description:Infections caused by carbapenem-resistant Acinetobacter baumannii (CRAb) are associated with high patient morbidity and mortality. The serious threat for human health imposed by CRAb was recently underscored by identification of close-to-untouchable carbapenem- and tetracycline-resistant isolates. Since outer membrane vesicles (OMVs) of Gram-negative bacteria may contribute to antimicrobial resistance, our present study was aimed at investigating OMVs produced by the first two carbapenem- and tetracycline-resistant CRAb isolates in Europe. These isolates, denoted CRAb1 and CRAb2 contain large, nearly identical plasmids that specify multiple resistances. Both isolates produce OMVs that were analyzed by differential light scattering, transmission electron microscopy and proteomics. By comparison with OMVs from the plasmid-free non-carbapenem-resistant A. baumannii isolate Ab1, which is an isogenic ancestor of the CRAb1 isolate, we show that plasmid carriage by the CRAb1 and CRAb2 isolates leads to an increased OMV size that is accompanied by increased diversity of the OMV proteome. Our analyses show that OMVs from CRAb1 and CRAb2 are major reservoirs of proteins involved in antimicrobial resistance, including the plasmid-encoded carbapenemases BlaNDM-1, and BlaOXA-97. We also show that these OMV-borne carbapenemases hydrolyze imipenem and protect otherwise carbapenem-sensitive A. baumannii and Escherichia coli isolates against this antibiotic. Altogether, our observations show that OMVs from highly drug-resistant CRAb confer tolerance against last-resort antibiotics to non-resistant bacterial pathogens.
Project description:Tandem duplication of carbapenemase genes amplifies the gene copy number and enhances carbapenem resistance. These amplifications are often heterogenous, transient, locate in plasmids, which often also contribute to heteroresistance. The duplication is especially important for low-hydrolysis activity enzymes, which is often overlooked or even under controversy. Here we reported an intrinsic oxacillinase duplication mediated by two neighbor ISAba1inserted in the same orientation. The duplication is relatively stable, located in chromosome, and the duplication times is up to twenty-five, much larger than previous reports. We provided genomic, transcriptomic, and proteomic evidence that the duplication resulted oxacillinase overproduction and thus contribute to carbapenem resistance. No other possible carbapenem resistance related changes (point mutations of oxaAb, disturbed expression of porin protein and efflux pump) were found during the duplication process. Furthermore, introducing oxaAb flanked by two ISAba1 to A. baumannii via plasmids, mimicked the in vivo duplication process under carbapenem stress. Taken together, ISAba1 mediated duplication of low activity intrinsic antibiotic hydrolysis enzymes could lead to antibiotic resistance for advanced-generation antibiotics.
Project description:Vibrio parahaemolyticus is the leading bacterial cause for seafood-related gastroenteritis worldwide. As an intestinal pathogen, V. parahaemolyticus competes with other commensal bacteria for the same pool of nutrients. The major source of nutrition for intestinal bacteria is intestinal mucus. We wanted to determine the expression profile of wild-type V. parahaemolyticus in mouse intestinal mucus and then perform a differential expression analysis in a ∆rpoN deletion mutant.
Project description:Background: Efflux pumps are important cofactors for carbapenem resistance in Enterobacter cloacae. The regulatory mechanism by which asmA influences efflux pump function in this species remains unclear. This study explored the regulatory role of asmA on efflux pumps in carbapenem-resistant Enterobacter cloacae. Results: Sixteen carbapenem-resistant Enterobacter cloacae were collected. All strains carried blaNDM, 87.5% of which were blaNDM-1 and 12.5% were blaNDM-5. PAβN had weak inhibition on carbapenem resistance in ST78 and strong inhibition in ST2260. ST2260(CY-8) was still resistant to carbapenems after elimination of blaNDM and could be inhibited by PAβN. However, ST78(CY-9) lost its resistance to carbapenems. Knockout of asmA reduced the MIC of ST2260 by 16-fold. ST78 showed no such changes. Growth curves revealed impaired growth only in ST2260ΔasmA. Transcriptomics/qRT-PCR revealed no significantly altered acrAB-tolC or marA expression in either strain. Membrane proteomics detected AcrB loss specifically in ST2260ΔasmA. The loss of asmA affected a wide range of membrane proteins, especially OmpW. Molecular docking predicted that AsmA could bind to AcrB, with stronger binding energy in ST78. The buried area of the CY-8 model involved 110 contact residues, while the number of contacts of the CY-9 model increased to 144. The AsmA chain of the two models had 46 common contact residues, and the AcrB chain had 60 common contact residues. AcrB of ST78 generally carries the I277V mutation. Conclusion: asmA is highly conserved in Enterobacter cloacae. It has functional heterogeneity in different ST types. In ST2260, asmA can affect efflux pump-mediated carbapenem resistance. AsmA can regulate AcrAB-TolC not by affecting marA. It is predicted that AsmA can maintain the carbapenem resistance of Enterobacter cloacae ST2260 by helping AcrB anchor to the inner membrane. The difference in carbapenem resistance mediated by efflux pumps between ST78 and ST2260 suggests that ST78 commonly carries the AcrB I277V mutation, which is a key site for efflux of β-lactams.
Project description:Carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a major global health threat, particularly in healthcare-associated infections. While carbapenemase- and porin-centered mechanisms are well characterized, how subinhibitory carbapenem exposure selects noncanonical adaptive routes remains unclear. Here, we show that subinhibitory meropenem promotes O_x001E_antigen loss in K. pneumoniae, predominantly mediated by insertion sequences (IS), thereby enhancing carbapenem resistance. O_x001E_antigen deficiency rewires metabolism under meropenem pressure, especially glycine, serine, and threonine pathways, dampening reactive oxygen species (ROS) accumulation and limiting oxidative killing; exogenous glycine restores ROS production and meropenem susceptibility. Genomic surveys reveal widespread O_x001E_antigen loss in K. pneumoniae, largely driven by IS, and also in Escherichia coli, and O_x001E_antigen–deficient mutants confirm its role in promoting carbapenem resistance. Importantly, this adaptation entails a trade-off: it improves survival under carbapenem pressure but increases serum susceptibility, destabilizes the capsule, attenuates virulence in murine infection models, and confers collateral sensitivity to aminoglycosides. These findings uncover a previously unrecognized route to carbapenem resistance that links O_x001E_antigen remodeling to metabolic rewiring, offering conceptual and therapeutic leverage points.
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.
2018-11-30 | GSE123106 | GEO
Project description:Comparison of biological traits in two non-intestinal Salmonella enterica strains from the same patient
Project description:Background: It remains unclear how high-risk Escherichia coli lineages, like sequence type (ST) 131, initially adapt to carbapenem exposure in its progression to becoming carbapenem resistant. Methods: Carbapenem mutation frequency was measured in multiple subclades of extended-spectrum β-lactamase (ESBL) positive ST131 clinical isolates using a fluctuation assay followed by whole genome sequencing (WGS) characterization. Genomic, transcriptomic, and porin analyses of ST131 C2/H30Rx isolate, MB1860, under prolonged, increasing carbapenem exposure was performed using two distinct experimental evolutionary platforms to measure fast vs. slow adaptation. Results: All thirteen ESBL positive ST131 strains selected from a diverse (n=184) ST131 bacteremia cohort had detectable ertapenem (ETP) mutational frequencies with a statistically positive correlation between initial ESBL gene copy number and mutation frequency (r = 0.87, P<1e-5). WGS analysis of mutants showed initial response to ETP exposure resulted in significant increases in ESBL gene copy numbers or mutations in outer membrane porin (Omp) encoding genes in the absence of ESBL gene amplification with subclade specific adaptations. In both experimental evolutionary platforms, MB1860 responded to initial ETP exposure by increasing blaCTX-M-15 copy numbers via modular, insertion sequence 26 (IS26) mediated pseudocompound transposons (PCTns). Transposase activity driven by PCTn upregulation was a conserved expression signal in both experimental evolutionary platforms. Stable mutations in Omp encoding genes were detected only after prolonged increasing carbapenem exposure consistent with clinical observations. Conclusions: ESBL gene amplification is a conserved response to initial carbapenem exposure, especially within the high-risk ST131 C2 subclade. Targeting such amplification could assist with mitigating carbapenem resistance development.
Project description:We performed RNA-Seq on acute promyelocytic leukemia (APL) cells treated with both all-trans retinoic acid (ATRA) and trichostatin A (TSA) to identify transcriptional changes potentially associated with changes in APL cell mechanical properties. As a control, we performed the same treatments and RNA-Seq analysis on HL-60 cells, which were derived from a patient diagnosed with APL but whose cells lacked the hallmark fusion gene associated with APL. We performed RNA-Seq on these three cell lines (AP-1060, NB4, HL-60) under different conditions (untreated, TSA, ATRA, TSA + ATRA), and identified differentially expressed genes between samples and conditions. This study identified differentially expressed genes and enriched gene sets associated with (1) a resistance to differentiation induced by ATRA or (2) changes in mechanical properties. Overall, we find evidence that ATRA resistance and mechanical properties may be linked by the degree of chromatin condensation in APL cells.