Project description:Carbapenem-resistant Acinetobacter baumannii (CRAB) is a critical nosocomial pathogen with limited treatment options. Although antibiotic resistance in CRAB is well-characterized, its interactions with host immunity and the contribution of outer membrane vesicles (OMVs) to pathogenesis remain poorly understood. We examined a clinical CRAB isolate and compared it with the reference strain A19606. Antimicrobial susceptibility testing revealed complete resistance of CRAB to commonly used antibiotics in clinical practice, while A19606 remained susceptible to most agents. In murine intranasal infection models and bone marrow-derived macrophages, CRAB induced significantly stronger activation of inflammatory signaling pathways and elevated levels of pro-inflammatory cytokines relative to A19606. Transcriptomic analysis of infected lung tissue identified differentially expressed genes, enriched for inflammatory response pathways. proteomics showed upregulated proteins in CRAB related to secretion systems. OMVs characterization revealed that CRAB-derived OMVs highly enriched in proteins associated with periplasmic and outer membrane spaces, and more potent in triggering macrophage inflammatory signaling. CRAB displays expansive antibiotic resistance and enhanced pro-inflammatory potential mediated in part by unique OMVs properties. Targeting OMVs formation or host immune modulation may represent effective strategies for combating CRAB infections.
Project description:Carbapenem-resistant Acinetobacter baumannii (CRAB) is a recognized nosocomial pathogen with limited therapeutics options. Lactic acid bacteria (LAB) constitute a promising therapeutic alternative. Here we aimed to study the antibacterial properties of a collection of LAB strains using phenotypic and transcriptomic analysis against A. baumannii clinical strains. One strain, Lacticaseibacillus rhamnosus CRL 2244, exerts a strong inhibitory capacity on A. baumannii with a strong killing activity. Scanning electron microscopy images showed changes in the morphology of A. baumannii with an increase formation of outer membrane vesicles. Significant changes in the expression levels a wide variety of genes were observed. Interestingly, most of the modified genes were involved in metabolic pathway known to be associated with bacterial survival. The paa operon, Hut system, and fatty acid degradation were some of the pathways that have been induced. The data reveals the impact of Lcb. rhamnosus CRL 2244 on A. baumannii response, resulting in bacterial stress and subsequent cell death. These findings highlight the antibacterial properties of Lcb. rhamnosus CRL 2244 and its potential as an alternative or complementary strategy for treating infections. Further exploration and development of this LAB as a treatment option could provide valuable alternatives for combating CRAB infections.
Project description:Carbapenem-resistant Acinetobacter baumannii (CRAb) is an urgent public health threat, according to the CDC. This pathogen has few treatment options and causes severe nosocomial infections with >50% fatality rate. Although previous studies have examined the proteome of CRAb, there have been no focused analyses of dynamic changes to β-lactamase expression that may occur due to drug exposure. Here, we present our initial proteomic study of variation in β-lactamase expression that occurs in CRAb with different β-lactam antibiotics. Briefly, drug resistance to Ab (ATCC 19606) was induced by the administration of various classes of β-lactam antibiotics, and the cell-free supernatant was isolated, concentrated, separated by SDS-PAGE, digested with trypsin, and identified by label-free LC-MS-based quantitative proteomics. Thirteen proteins were identified and evaluated using a 1789 sequence database of Ab β-lactamases from UniProt, the majority of which were Class C β-lactamases (≥80%). Importantly, different antibiotics, even those of the same class (e.g. penicillin and amoxicillin), induced non-equivalent responses comprising various isoforms of Class C and D serine-β-lactamases, resulting in unique resistomes. These results open the door to a new approach of analyzing and studying the problem of multi-drug resistance in bacteria that rely strongly on β-lactamase expression.
Project description:Crab is one of the major source for V. parahaemolyticus outbreak among aquatic products in Northeast Asian due to improperly cooking and wound infection by mishandling. However, there is no report on whole genome sequence of V. parahaemolyticus isolated from contaminated crab, thus no information is available for major virulence factors about V. parahaemolyticus obtained from crab. Therefore, the analysis of transcriptome of isolated V. parahaemolyticus from crab products are necessary to investigate potential risk of foodborne illness by contaminated products.
Project description:The emergence of multi-drug resistant pathogens is a major public health problem, leading to rethink and innovate in our bacterial control strategies. Here, we explore the anti-biofilm and anti-virulence activities of nineteen 6-polyaminosterol derivatives (squalamine-based), presenting a modulation of their polyamine side chain, on 4 major pathogens, i.e. carbapenem-resistant A. baumannii (CRAB) and P. aeruginosa (CRPA), a methicillin-resistant S. aureus (MRSA) and a vancomycin-resistant E. faecium (VRE) strains. We screened the effect of these derivatives on biofilm formation and eradication. 4e (for CRAB, VRE and MRSA) and 4f (for all the strains) were the most potent one and displayed activities as good as conventional antibiotics. We also identified 11 compounds able to decrease by more than 40% the production of pyocyanin, a major virulence factor of P. aeruginosa. We demonstrated that 4f treatment acts against bacterial infections in Galleria mellonella and significantly prolonged the larvae survival (from 50% to 80%) after 24 h of CRAB, VRE and MRSA infections. As shown by proteomic studies, 4f triggered distinct cellular responses depending on the bacterial species, but essentially related to the cell envelop. Its interesting anti-biofilm and anti-virulence properties make it promising candidate for use in therapeutics.
Project description:Pseudomonas aeruginosa is a leading cause of nosocomial infection and is responsible for severe acute and chronic infections such as pneumonia, urinary tract infections and lung infections in cystic fibrosis patients. The bacterium possesses a type 3 secretion system whose expression is linked with poor outcomes in both animal models and human patients. In particular, this syringe-like apparatus injects ExoU, the most toxic T3SS effector. However, the mechanism of ExoU in P. aeruginosa’s virulence remains elusive compare to the other T3SS toxins. It was previously suggested that the toxin uses a host trafficking system to reach the plasma membrane and to induce cell necrosis. In this work, we demonstrated that once injected into the cell cytoplasm, ExoU binds to DNAJC5+ vesicles to rapidly reach the plasma membrane.
Project description:The opportunistic bacterium Pseudomonas aeruginosa is a major nosocomial pathogen causing both devastating acute and chronic persistent infections. During the course of an infection, P. aeruginosa rapidly adapts to the specific conditions within the host. In the present study, we aimed at the identification of genes that are highly expressed during biofilm infections such as in chronically infected lungs of patients with cystic fibrosis (CF), burn wounds and subcutaneous mouse tumours. We found a common subset of differentially regulated genes in all three in vivo habitats and evaluated whether their inactivation impacts on the bacterial capability to form biofilms in vitro and to establish biofilm-associated infections in a murine model. Additive effects on biofilm formation and host colonization were discovered by the combined inactivation of several highly expressed genes. However, even combined inactivation was not sufficient to abolish the establishment of an infection completely. These findings can be interpreted as evidence that either redundant traits encode functions that are essential for in vivo survival and chronic biofilm infections and/or bacterial adaptation is considerably achieved independently of transcription levels. Supplemental screens, will have to be applied in order to identify the minimal set of key genes essential for the establishment of chronic infectious diseases. Ex-vivo samples were collected from burn wound, cystic fibrosis patients mucous and mice tumor and stabilized for the RNA extraction. Recovered clinical strains were cultivated in rich medium control conditions untill the early stationary phase and RNA was extracted. The murine tumors were infected with burn wound isolated strains
Project description:Background: The Scylla paramamosain is a very important aquaculture crustacean species in the southeast coastal areas of China including Shantou. For the past few years, mud crab cultured in Niutianyang of Shantou suffered from serious diseases, especially the bacterial diseases (such as Vibrio parahaemolyticus). In eukaryotes, small RNAs can regulate gene expression in post-transcription to act on host-pathogen interaction system. Aims: V.parahaemolyticus isolated from Shantou Niutianyang crab culture area was injected to S.paramamosains to carry out an essential analysis on global miRNA expression in diverse tissues between two groups by the Illumina Solex deep sequencing technology. Methodology:To examine the relationship between mud crab miRNA expression and the bacterial pathogen, we collected mixed two pools of equal amounts of RNA from 7 different mud crab tissues (mesenteron, heart, liver, gill, brain, muscle and blood) and sequencing by Illumine/Solexa deep sequencing technology under normal conditions and during infection with V.parahaemolyticus. The high throughput sequencing resulted in 19,144,358 and 18,559,070 raw reads corresponding to 17,496,577 and 16,888,096 high-quality mappable reads for the normal and infected mixed pools, respectively. Stem-loop RT-qPCRs were used to confirm the microRNAs expression in different tissues of two pools. The results show that miRNAs might play a key role in regulating gene expression during mud crab S.paramamosain infection with V.parahaemolyticus. Conclusions: We identified a large number of miRNAs during the mud crab Scylla paramamosain infection with V.parahaemolyticus, some of which are differentially expressed between the treatments and the controls. The study provides an opportunity for further understanding of small RNA function in the regulation of molecular response and gives us clues for further studies of the mechanisms of V.parahaemolyticus infection in mud crab.
Project description:Pseudomonas aeruginosa (Pa) is one of the main causative agents of nosocomial infections and the spread of multidrug-resistant strains is rising. The outer membrane composition of Pa restricts antibiotic entry and determines virulence. For efficient outer membrane protein biogenesis, the BAM complex and chaperones like Skp and SurA are crucial. Deletion mutants of bamB, bamC and the skp homolog hlpA as well as a conditional mutant of surA were investigated. The most profound effects were associated with a lack of SurA, characterized by increased membrane permeability, enhanced sensitivity to antibiotic treatment and attenuation of virulence in a Galleria mellonella infection model. Strikingly, the conditional deletion of surA in a multidrug-resistant bloodstream isolate re-sensitized the strain to antibiotic treatment. Mass spectrometry revealed striking alterations in the outer membrane composition. Thus, SurA of Pa is important for the insertion of many porins, type V secretion systems, TonB-dependent receptors, proteins involved in LPS transport and BAM complex components. Therefore, SurA of Pa serves as a promising target for developing a drug that shows antiinfective activity and sensitizes multidrug-resistant strains to antibiotics.