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The ISME Journal Jan 2024Intestinal microbial disturbance is a direct cause of host disease. The bacterial Type VI secretion system (T6SS) often plays a crucial role in the fitness of pathogenic...
Intestinal microbial disturbance is a direct cause of host disease. The bacterial Type VI secretion system (T6SS) often plays a crucial role in the fitness of pathogenic bacteria by delivering toxic effectors into target cells. However, its impact on the gut microbiota and host pathogenesis is poorly understood. To address this question, we characterized a new T6SS in the pathogenic Aeromonas veronii C4. First, we validated the secretion function of the core machinery of A. veronii C4 T6SS. Second, we found that the pathogenesis and colonization of A. veronii C4 is largely dependent on its T6SS. The effector secretion activity of A. veronii C4 T6SS not only provides an advantage in competition among bacteria in vitro, but also contributes to occupation of an ecological niche in the nutritionally deficient and anaerobic environment of the host intestine. Metagenomic analysis showed that the T6SS directly inhibits or eliminates symbiotic strains from the intestine, resulting in dysregulated gut microbiome homeostasis. In addition, we identified three unknown effectors, Tse1, Tse2, and Tse3, in the T6SS, which contribute to T6SS-mediated bacterial competition and pathogenesis by impairing targeted cell integrity. Our findings highlight that T6SS can remodel the host gut microbiota by intricate interplay between T6SS-mediated bacterial competition and altered host immune responses, which synergistically promote pathogenesis of A. veronii C4. Therefore, this newly characterized T6SS could represent a general interaction mechanism between the host and pathogen, and may offer a potential therapeutic target for controlling bacterial pathogens.
Topics: Type VI Secretion Systems; Gastrointestinal Microbiome; Aeromonas veronii; Symbiosis; Ecosystem; Bacterial Proteins
PubMed: 38531781
DOI: 10.1093/ismejo/wrae053 -
Fish & Shellfish Immunology Aug 2023Aeromonas veronii is a zoonotic agent capable of infecting fish and mammals, including humans, posing a serious threat to the development of aquaculture and public...
Immunological effects of recombinant Lactobacillus casei expressing pilin MshB fused with cholera toxin B subunit adjuvant as an oral vaccine against Aeromonas veronii infection in crucian carp.
Aeromonas veronii is a zoonotic agent capable of infecting fish and mammals, including humans, posing a serious threat to the development of aquaculture and public health safety. Currently, few effective vaccines are available through convenient routes against A. veronii infection. Herein, we developed vaccine candidates by inserting MSH type VI pili B (MshB) from A. veronii as an antigen and cholera toxin B subunit (CTB) as a molecular adjuvant into Lactobacillus casei and evaluated their immunological effect as vaccines in a crucian carp (Carassius auratus) model. The results suggested that recombinant L. casei Lc-pPG-MshB and Lc-pPG-MshB-CTB can be stably inherited for more than 50 generations. Oral administration of recombinant L. casei vaccine candidates stimulated the production of high levels of serum-specific immunoglobulin M (IgM) and increased the activity of acid phosphatase (ACP), alkaline phosphatase (AKP) superoxide dismutase (SOD), lysozyme (LZM), complement 3 (C3) and C4 in crucian carp compared to the control group (Lc-pPG612 group and PBS group) without significant changes. Moreover, the expression levels of interleukin-10 (IL-10), interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α) and transforming growth factor-β (TGF-β) genes in the gills, liver, spleen, kidney and gut of crucian carp orally immunized with recombinant L. casei were significantly upregulated compared to the control groups, indicating that recombinant L. casei induced a significant cellular immune response. In addition, viable recombinant L. casei can be detected and stably colonized in the intestine tract of crucian carp. Particularly, crucian carp immunized orally with Lc-pPG-MshB and Lc-pPG-MshB-CTB exhibited higher survival rates (48% for Lc-pPG-MshB and 60% for Lc-pPG-MshB-CTB) and significantly reduced loads of A. veronii in the major immune organs after A. veronii challenge. Our findings indicated that both recombinant L. casei strains provide favorable immune protection, with Lc-pPG-MshB-CTB in particular being more effective and promising as an ideal candidate for oral vaccination.
Topics: Humans; Animals; Lacticaseibacillus casei; Cholera Toxin; Fimbriae Proteins; Aeromonas veronii; Carps; Bacterial Vaccines; Vaccines, Synthetic; Fish Diseases; Mammals
PubMed: 37419434
DOI: 10.1016/j.fsi.2023.108934 -
Frontiers in Veterinary Science 2024is a significant pathogen to various aquatic life. Infections in fish can lead to high mortality rates, causing substantial economic losses in aquaculture. Vaccination...
INTRODCTION
is a significant pathogen to various aquatic life. Infections in fish can lead to high mortality rates, causing substantial economic losses in aquaculture. Vaccination is proposed as a substitute for antibiotics in aquaculture to decrease disease-related mortality and morbidity. Our study previously constructed a -deleted strain of , which provided protective effect to .
METHODS
To further assess the vaccine's applicability, this study evaluated its genetic stability and safety, and the immune protective effects in through four distinct administration routes: intraperitoneal injection, intramuscular injection, oral administration, and immersion, to determine the efficacy of these administration routes.
RESULTS
The results showed that the vaccine remained genetically stable after 45 generations. Immunization via these administration routes was safe for , with intraperitoneal and intramuscular injections causing stronger adverse reactions. Immersion immunization resulted in mild adverse reactions, and no significant adverse reactions were observed following oral immunization. Immunizing at safe concentrations via these routes enhanced the phagocytic activity in serum, increased the levels of non-specific immune-related enzymes (ACP, AKP, C3, C4, LZM, SOD, and IgM), and improved specific serum antibody levels. It also elevated levels of cytokines related to inflammatory responses (IL-1β, IL-10, TNF-α, TGF-β) in organ tissues (liver, spleen, kidney, mid-post intestine, and gills). The survival rates of were measured after challenging with the virulent strain , resulting in the relative survival rates of 64% for Intraperitoneal vaccine group, 56% for Intramuscular vaccine group, 52% for oral vaccine group, and 48% for immersion vaccine group. Analysis of bacterial load in the liver, spleen, and kidney post-challenge showed a decreasing trend in the control group, indicating that the vaccine strain could gradually restrict the rapid proliferation of bacteria in these tissues, thereby providing a certain level of immune protection against .
DISCUSSION
In brief, the vaccine strain can serve as a safe live attenuated vaccine for , and this study lays the foundation for the development of live attenuated vaccines against .
PubMed: 38577546
DOI: 10.3389/fvets.2024.1378448 -
Virulence Dec 2023The emergence of antibiotic-resistant strains in clinical settings has presented an escalating burden on human and public health. The dissemination of antibiotic...
The emergence of antibiotic-resistant strains in clinical settings has presented an escalating burden on human and public health. The dissemination of antibiotic resistance in is predominantly facilitated by chromosome-borne accessory genetic elements, although the existing literature on this subject remains limited. Hence, the primary objective of this study is to comprehensively investigate the genomic characteristics of chromosome-borne accessory genetic elements in . Moreover, the study aims to uncover novel genetic environments associated with antibiotic resistance on these elements. were screened from nonduplicated strains collected from two tertiary hospitals in China. Complete sequencing and population genetics analysis were performed. BLAST analysis was employed to identify related elements. All newly identified elements were subjected to detailed sequence annotation, dissection, and comparison. We identified and newly designated 19 chromosomal elements, including 18 integrative and mobilizable elements (IMEs) that could be classified into four categories: Tn-related, Tn-related, Tn-related, and Tn-related IMEs. Each class exhibited a distinct pattern in the types of resistance genes carried by the IMEs. Several novel antibiotic resistance genetic environments were uncovered in these elements. Notably, we report the first identification of the gene and gene in clinical genome, the first presence of a (E)-(E) resistance gene environment within the backbone region in IMEs, and a new resistance gene environment. The implications of these findings are substantial, as they provide new insights into the evolution, structure, and dissemination of chromosomal-borne accessory elements.
Topics: Humans; Aeromonas; Drug Resistance, Microbial; Anti-Bacterial Agents; Chromosomes; China
PubMed: 37848422
DOI: 10.1080/21505594.2023.2271688 -
BMC Veterinary Research Jan 2024Aeromonas species are one of the most important etiologies of diseases in fish farms, leading to clinical manifestation and mortality and are associated with public...
BACKGROUND
Aeromonas species are one of the most important etiologies of diseases in fish farms, leading to clinical manifestation and mortality and are associated with public health risks. This study aimed to investigate the prevalence, phenotypic and molecular characteristics of Aeromonas species isolated from farmed Clarias gariepinus using 16 S rRNA sequencing. Additionally, their antibiogram and multiple antibiotic resistance index were determined using a disc diffusion test.
RESULTS
A total of 230 Aeromonas strains were isolated from Clarias gariepinus with 40.9% obtained from diseased fish, and 25% isolated from apparently healthy ones. Five different species including Aeromonas caviae, Aeromonas veronii, Aeromonas hydrophila, Aeromonas dhakensis and Aeromonas enteropelogenes were fully identified and genetically characterized. Based on the available literature, this is the first report of Aeromonas enteropelogenes from the study area. The phylogenetic analysis showed genetic heterogeneity and distance within the species and the reference strains. The multiple resistant Aeromonas species were susceptible to ciprofloxacin, gentamycin, and florfenicol. The Aeromonas species' multiple antibiotic resistance index values varied between 0.20 and 0.80 and were isolated from the farms where antibiotics were intensively used.
CONCLUSIONS
The diversity of multidrug-resistant Aeromonas species isolated from fish farms is a major threat to fish production giving us more understanding of epidemiology and the multidrug Aeromonas species with a MAR index of greater than 0.2 were isolated from farms where antibiotic use was widespread. As a result, a considerably increased danger of multiple antibiotic resistance spreading to the fish culture environment may impact aquaculture production. Hence there is a need for appropriate and monitored drug usage.
Topics: Animals; Catfishes; Phylogeny; Aeromonas; Drug Resistance, Microbial; Anti-Bacterial Agents
PubMed: 38184574
DOI: 10.1186/s12917-023-03860-5 -
Open Forum Infectious Diseases Dec 2023The genus is increasingly implicated in human infections, but knowledge of its clinical characteristics and antimicrobial resistance profiles has been limited owing to...
BACKGROUND
The genus is increasingly implicated in human infections, but knowledge of its clinical characteristics and antimicrobial resistance profiles has been limited owing to its complex taxonomy.
METHODS
We conducted a multicenter prospective cohort study of patients with infections at hospitals across Japan. Patients were eligible for inclusion if they had an spp. strain in a clinical culture and were considered infected at the culture site. Clinical data were collected, and isolates underwent susceptibility testing and whole-genome sequencing.
RESULTS
A total of 144 patients were included. Hepatobiliary infection accounted for a majority of infections (73% [105 of 144]), which mostly occurred in elderly patients with comorbid conditions, including hepatobiliary complications. The all-cause 30-day mortality rate was 10.0% (95% confidence interval, 4.9%-14.8%). By whole-genome sequencing, 141 strains (98%) belonged to 4 species, , , and with significant intraspecies diversity. was predominant in all infection sites except skin and soft tissue, for which was the prevailing species. The genes encoding chromosomally mediated class B, C, and D β-lactamases were harbored by 92%-100% of the isolates in a species-specific manner, but they often lacked association with resistance phenotypes. The activity of cefepime was reliable. All isolates of and carried an like colistin resistance gene and showed reduced susceptibility to colistin.
CONCLUSIONS
Hepatobiliary tract was the most common infection site of spp., with being the dominant causative species. The resistance genotype and phenotype were often incongruent for β-lactam agents.
PubMed: 38156048
DOI: 10.1093/ofid/ofad587 -
Infection and Drug Resistance 2024Hospital wastewater (HWW) promotes the spread of carbapenem resistance genes (CRGs). carry a large number of CRGs in HWW, they may play a role as a suitable reservoir...
BACKGROUND
Hospital wastewater (HWW) promotes the spread of carbapenem resistance genes (CRGs). carry a large number of CRGs in HWW, they may play a role as a suitable reservoir for CRGs, while resistomes in HWW are still poorly characterized regarding carbapenem resistant . Thus, the aim of the study was to evaluate the molecular epidemiological characteristics of carbapenem resistant in HWW.
METHODS
A total of 33 carbapenem resistant were isolated from HWW. Antimicrobial susceptibility testing and polymerase chain reaction (PCR) were used to assess the antimicrobial resistance profiles. Molecular typing was performed using enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) and multilocus sequence typing (MLST). The horizontal transmission mode of was explored through conjugation and transformation experiments. The stability of -IncP-6 plasmids was assessed through plasmid stability and in vitro competition test. The PCR mapping method was used to investigate the structural diversity of .
RESULTS
The detection rates of and in were 97.0% and 39.4% respectively. were grouped into 13 clusters by ERIC-PCR and 12 STs by MLST. were grouped into 11 clusters by ERIC-PCR and 4 STs by MLST. 56.3% were located on mobilizable IncP-6 plasmids. -IncP-6 plasmid showed high stability and low cost fitness.
CONCLUSION
Carbapenem resistant from HWW mainly carried , which exhibited great structural diversity. might serve as reservoirs for and might spread mainly through transformation in HWW.
PubMed: 38912216
DOI: 10.2147/IDR.S460715 -
Journal of Advanced Veterinary and... Sep 2023Whole genome sequencing (WGS) of Alim_AV_1000 isolated from ulcerative lesions of Shing fish (stringing catfish; ) was performed during the outbreak year 2021.
OBJECTIVE
Whole genome sequencing (WGS) of Alim_AV_1000 isolated from ulcerative lesions of Shing fish (stringing catfish; ) was performed during the outbreak year 2021.
MATERIALS AND METHODS
Using next-generation sequencing (Illumina) technology, WGS was accomplished, resulting in the sequencing, assembly, and analysis of the entire genome of the strain. Moreover, the genomic features, virulence factors, antimicrobial resistome, and phylogenetic analysis for the molecular evolution of this strain were also examined.
RESULTS
The genome size of the Alim_AV_1000 strain was 4,494,515 bp, with an average G+C content of 58.87%. Annotation revealed the known transporters and genes linked to virulence, drug targets, and antimicrobial resistance.
CONCLUSION
The findings of the phylogenetic analysis revealed that the strain of the present study has a close relationship with the China strain TH0426 and strain B56. This study provides novel information on isolated from Shing fish in Bangladesh.
PubMed: 37969805
DOI: 10.5455/javar.2023.j711 -
Environmental Research Oct 2023Finding effective methods for simultaneous removal of eutrophic nutrients and heavy metals has attracted increasing concerns for the environmental remediation. Herein, a...
Finding effective methods for simultaneous removal of eutrophic nutrients and heavy metals has attracted increasing concerns for the environmental remediation. Herein, a novel auto-aggregating aerobic denitrifying strain (Aeromonas veronii YL-41) was isolated with capacities for copper tolerance and biosorption. The denitrification efficiency and nitrogen removal pathway of the strain were investigated by nitrogen balance analysis and amplification of key denitrification functional genes. Moreover, the changes in the auto-aggregation properties of the strain caused by extracellular polymeric substances (EPS) production were focused on. The biosorption capacity and mechanisms of copper tolerance during denitrification were further explored by measuring changes in copper tolerance and adsorption indices, as well as by variations in extracellular functional groups. The strain showed extremely strong total nitrogen removal ability, with 67.5%, 82.08% and 78.48% of total nitrogen removal when NH-N, NO-N, and NO-N were used as the only initial nitrogen source, respectively. The successful amplification of napA, nirK, norR, and nosZ genes further demonstrated that the strain accomplished nitrate removal through a complete aerobic denitrification pathway. The production of protein-rich EPS of up to 23.31 mg/g and an auto-aggregation index of up to 76.42% may confer a strong biofilm-forming potential to the strain. Under the stress of 20 mg/L copper ions, the removal of nitrate-nitrogen was still as high as 71.4%. In addition, the strain could achieve an efficient removal of 96.9% of copper ions at an initial concentration of 80 mg/L. Scanning electron microscopy and deconvolution analysis of characteristic peaks confirmed that the strains encapsulate heavy metals by secreting EPS and, meanwhile, form strong hydrogen bonding structures to enhance intermolecular forces to resist copper ion stress. This study provides an innovative and effective biological approach for the synergistic bioaugmentation removal of eutrophic substances and heavy metals from aquatic environments.
Topics: Wastewater; Nitrates; Denitrification; Copper; Nitrogen; Aerobiosis; Bacteria; Organic Chemicals
PubMed: 37429397
DOI: 10.1016/j.envres.2023.116602 -
Virus Research Oct 2023Aeromonas is one of the most serious pathogens in freshwater aquaculture. Overuse of antibiotics for the treatment of fish diseases has led to the frequent occurrence of...
Aeromonas is one of the most serious pathogens in freshwater aquaculture. Overuse of antibiotics for the treatment of fish diseases has led to the frequent occurrence of drug-resistant strains. Phage therapy is an alternative approach to overcoming the multi-drug resistance associated with antibiotics. In this study, a novel phage phiA034 targeting the host A. veronii A034 was isolated. The phage could infect 14 strains of 4 species Aeromonas. The phage phiA034 displayed head-tail structure with an icosahedral head in the TEM image. At the optimal MOI of 1, it had a latent period of nearly 20 minutes and a burst size of 286 PFU/cell. Besides, the phage phiA034 exhibited high tolerance to a wide range of temperature (30-70 °C) and acid-base (pH 6.0-10.0). The whole genome of phage phiA034 was sequenced with a size of 61,443 bp and annotated with 82 ORFs, mainly related to structure, DNA replication, and lysis. Based on the analysis and comparison of the genomes and proteomes, phage phiA034 could be classified as a novel species of an existing genus Duplodnaviria Heunggongvirae, Uroviricota, Caudoviricetes, Casjensviridae, Sharonstreetvirus. These findings have expanded the species bank and genomes library of bacterial virus and will promote the application of phage therapy in Aeromonas disease.
Topics: Animals; Bacteriophages; Aeromonas; DNA, Viral; Genome, Viral; Anti-Bacterial Agents
PubMed: 37579848
DOI: 10.1016/j.virusres.2023.199193