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Frontiers in Veterinary Science 2022The fast-growing demand for aquatic products has led to the rapid development of aquaculture. However, diseases caused by bacterial pathogens result in severe economic...
The fast-growing demand for aquatic products has led to the rapid development of aquaculture. However, diseases caused by bacterial pathogens result in severe economic losses all over the world. Although the introduction of antibiotics to aquaculture decreased the mortality of infectious diseases, the emergence of antibiotic resistance caused treatment failure. Therefore, drugs with novel strategies are needed for combatting infections caused by resistant bacterial strains. In the present study, aerolysin was identified as a target for developing drugs from natural compounds against () infections. We found that polydatin without an inhibitory effect against growth could decrease the hemolysis mediated by aerolysin. In both western blot and qPCR assays, the addition of polydatin decreased the production of aerolysin by downregulating the aerolysin encoding gene. Moreover, cell viability and animal studies found that polydatin could reduce the pathogenesis of both and . Taken together, these findings provided a novel approach and candidate for treating resistant infections in aquaculture.
PubMed: 35909695
DOI: 10.3389/fvets.2022.937463 -
Veterinary World Jan 2022Antibiotic resistance has been a progressively documented problem, resulting in treatment failure in humans and animals. This study aimed to investigate the...
BACKGROUND AND AIM
Antibiotic resistance has been a progressively documented problem, resulting in treatment failure in humans and animals. This study aimed to investigate the antimicrobial susceptibility and virulence of extensively drug-resistant (XDR) spp. in wild and its surrounding seawater along the coastal road of Port Said, Egypt.
MATERIALS AND METHODS
Specimens were examined bacteriologically, confirmed biochemically, and tested for their sensitivity against 11 antimicrobial agents. Molecular confirmation of the obtained isolates by was performed, followed by the detection of antimicrobial resistance and virulence genes.
RESULTS
spp. was recovered from fish (44%) and water samples (36%). was the most prevalent identified strain, followed by , , and . Moreover, 90% of the tested isolates were multidrug-resistant (MDR), while 26.67% were XDR. Tested isolates were resistant to b-lactams and sulfonamides (100%), oxytetracycline (90%), and streptomycin (62.22%) but completely susceptible to cefotaxime. XDR isolates successfully amplified resistance genes (, and ()) but not the () gene, although there was phenotypic resistance to streptomycin on plates. All XDR isolates carry the cytotoxic enterotoxin gene (), but gene was detected in only one isolate (12.5%).
CONCLUSION
Data in this study provide a recent update and highlight the role of wild mullet and seawater as reservoirs for MDR and XDR spp. that may pose a risk to humans as food-borne infection or following direct contact.
PubMed: 35369605
DOI: 10.14202/vetworld.2022.55-64 -
Frontiers in Microbiology 2022is an important zoonotic pathogen responsible for septicemia, diarrhea and gastroenteritis, and has attracted considerable attention. The EnvZ/OmpR two-component system...
is an important zoonotic pathogen responsible for septicemia, diarrhea and gastroenteritis, and has attracted considerable attention. The EnvZ/OmpR two-component system (TCS) mediates environmental stress responses in gram-negative bacteria. We investigated the role of the TCS in by comparing the characteristics of the parental (), EnvZ/OmpR knockout (), and complemented strains (). Under non-stress conditions, the strain showed a significant decrease in growth rate compared to that of . Transcriptome and metabonomic analysis indicated that many metabolic pathways were remarkably affected in the ΔEnvZ/OmpR strain, including the TCA cycle and arginine biosynthesis. In addition, the virulence of the ΔEnvZ/OmpR strain was attenuated in a Kunming mouse model. The ΔEnvZ/OmpR strain exhibited notably reduced tolerance to environmental stresses, including high temperature, different pH conditions, oxidative stress, and high osmotic stress. The downregulated expression of genes related to cell metabolism, motility, and virulence in the ΔEnvZ/OmpR mutant strain was further validated by real-time quantitative PCR. Consequently, our data suggest that the EnvZ/OmpR TCS is required for growth, motility, virulence, and stress response in , which has significant implications in the development of novel antibacterial and vaccine therapies targeting EnvZ/OmpR against .
PubMed: 36312957
DOI: 10.3389/fmicb.2022.1032969 -
Frontiers in Veterinary Science 2022is a ubiquitous bacterium with various hosts that causes mass mortality in farm-raised fish species and significant economic losses. The current antibiotic treatment is... (Review)
Review
is a ubiquitous bacterium with various hosts that causes mass mortality in farm-raised fish species and significant economic losses. The current antibiotic treatment is ineffective in controlling this bacterium infection in aquaculture species. Therefore, an evaluation of potential phytobiotics is needed to find an alternative antimicrobial agent to reduce the over-reliance on antibiotics in aquaculture and safeguard public and environmental health. Furthermore, the rise in antibiotic resistance cases among pathogenic bacteria indicates an urgent need for new fish and shellfish health management solutions. In this context, phytobiotics applications in aquaculture can be defined as any medicinal plant-based antimicrobial agent used in fish and shellfish health management. This review will focus on the impacts of Motile Aeromonas Septicemia (MAS) due to in aquaculture, the potential of phytobiotics in enhancing the tolerance of aquaculture species against MAS and the combination of phytobiotics with other antimicrobial and therapeutic agents against MAS.
PubMed: 36277060
DOI: 10.3389/fvets.2022.1023784 -
International Journal of Molecular... Jun 2024Grass Carp Reovirus (GCRV) and (Ah) are the causative agents of haemorrhagic disease in grass carp. This study aimed to investigate the molecular mechanisms and immune... (Comparative Study)
Comparative Study
Grass Carp Reovirus (GCRV) and (Ah) are the causative agents of haemorrhagic disease in grass carp. This study aimed to investigate the molecular mechanisms and immune responses at the miRNA, mRNA, and protein levels in grass carp kidney cells (CIK) infected by Grass Carp Reovirus (GCRV, NV) and (Bacteria, NB) to gain insight into their pathogenesis. Within 48 h of infection with Grass Carp Reovirus (GCRV), 99 differentially expressed microRNA (DEMs), 2132 differentially expressed genes (DEGs), and 627 differentially expressed proteins (DEPs) were identified by sequencing; a total of 92 DEMs, 3162 DEGs, and 712 DEPs were identified within 48 h of infection with . It is worth noting that most of the DEGs in the NV group were primarily involved in cellular processes, while most of the DEGs in the NB group were associated with metabolic pathways based on KEGG enrichment analysis. This study revealed that the mechanism of a grass carp haemorrhage caused by GCRV infection differs from that caused by the infection. An important miRNA-mRNA-protein regulatory network was established based on comprehensive transcriptome and proteome analysis. Furthermore, 14 DEGs and 6 DEMs were randomly selected for the verification of RNA/small RNA-seq data by RT-qPCR. Our study not only contributes to the understanding of the pathogenesis of grass carp CIK cells infected with GCRV and but also serves as a significant reference value for other aquatic animal haemorrhagic diseases.
Topics: Aeromonas hydrophila; Animals; Carps; MicroRNAs; Transcriptome; RNA, Messenger; Reoviridae; Proteomics; Fish Diseases; Gene Expression Profiling; Gram-Negative Bacterial Infections; Cell Line; Reoviridae Infections; Gene Regulatory Networks
PubMed: 38928143
DOI: 10.3390/ijms25126438 -
The Journal of Veterinary Medical... Dec 2019Aeromonas hydrophila causes disease in fish known as Motile Aeromonas Septicemia (MAS), also named as bacterial hemorrhagic septicemia. In this study, a pathogenic A....
Aeromonas hydrophila causes disease in fish known as Motile Aeromonas Septicemia (MAS), also named as bacterial hemorrhagic septicemia. In this study, a pathogenic A. hydrophila strain was isolated from common carp Cyprinus carpio L., which were suffering from severe hemorrhagic septicemia. According to the phylogenetic analysis derived from 16S rDNA sequence, the isolate formed a single branch in the A. hydrophila group, named AhHN1. Artificial infection results indicated that AhHN1 showed strong pathogenicity in C. carpio and the LD was 1.38 × 10 CFU/fish, the clinical symptoms and pathological features of infected fish were similar to those observed in natural infections. The antimicrobial susceptibility testing revealed that AhHN1 resistance to more than 13 kinds of antimicrobial agents. However, the AhHN1 strain exhibited an extremely sensitivity to enrofloxacin, the in vitro activities of enrofloxacin were subsequently investigated and drug selection window (MSW) was 0.0016-0.0125 µg/ml. Pharmacokinetics data showed that plasma concentration of enrofloxacin was 0.0016, 0.0148 and 0.0282 µg/ml at 24 hr after orally administered with 2.5, 5 and 10 mg/kg enrofloxacin. Moreover, dosing once a day of 2.5, 5 and 10 mg/kg enrofloxacin, which the relative protection ratio (RPS) was amounted to 33.3, 66.7, and 83.3%, respectively. Therefore, 5 mg/kg enrofloxacin was considered to be the rational regimen for controlling AhHN1 infection in C. carpio in the countries where the use of enrofloxacin is permitted in aquaculture. The aim of this study was to establish a scientific medication regimen for the prevention and therapy of the mutidrug-resistant A. hydrophila infection.
Topics: Aeromonas hydrophila; Animals; Anti-Bacterial Agents; Aquaculture; Carps; Drug Resistance, Multiple; Enrofloxacin; Fish Diseases; Gram-Negative Bacterial Infections; Hemorrhagic Septicemia
PubMed: 31406034
DOI: 10.1292/jvms.19-0025 -
Microorganisms Feb 2024, a Gram-negative bacterium widely found in freshwater environments, acts as a common conditional pathogen affecting humans, livestock, and aquatic animals. In this...
, a Gram-negative bacterium widely found in freshwater environments, acts as a common conditional pathogen affecting humans, livestock, and aquatic animals. In this study, the impact of oridonin, an -kaurane diterpenoid compound derived from , on the virulence factors of AS 1.1801 and its antibacterial mechanism was elucidated. The minimum inhibitory concentration (MIC) of oridonin against AS 1.1801 was 100 μg/mL. Oridonin at inhibitory concentrations could significantly increase the electrical conductivity in the supernatant and escalate nucleic acid leakage ( < 0.01). This effect was concomitant with observed distortions in bacterial cells, the formation of cytoplasmic cavities, cellular damage, and pronounced inhibition of protein and nucleic acid synthesis. Additionally, oridonin at inhibitory levels exhibited a noteworthy suppressive impact on AS 1.1801 across biofilm formation, motility, hemolytic activity, lipase activity, and protease activity ( < 0.05), demonstrating a dose-dependent enhancement. qRT-PCR analysis showed that the gene expression of , and were significantly downregulated after oridonin treatment in AS 1.1801 ( < 0.05). Our results indicated that oridonin possessed significant antibacterial and anti-virulence effects on AS 1.1801.
PubMed: 38399819
DOI: 10.3390/microorganisms12020415 -
Virulence Dec 2022The immunogenicity of Aha1, an OMP of mediating the adhesion of bacteria onto the mucosal surface of hosts has been established. In this study, recombinant vectors,...
The immunogenicity of Aha1, an OMP of mediating the adhesion of bacteria onto the mucosal surface of hosts has been established. In this study, recombinant vectors, pPG1 and pPG2, carrying a 1366 bp DNA fragment that was responsible for encoding the 49 kDa Aha1 from were constructed, respectively, then electroporated into a probiotic strain CC16 separately to generate two types of recombinants, pPG1-Aha1 (Lc-pPG1-Aha1) and -pPG2-Aha1 (Lc-pPG2-Aha1). Subsequently, these were orally administered into common carps to examine their immunogenicity. The expression and localization of the expressed Aha1 protein relative to the carrier was validated via Western blotting, flow cytometry, and immune fluorescence separately. The recombinant vaccines produced were shown high efficacies, stimulated higher level of antibodies and AKP, ACP, SOD, LZM, C3, C4 in serum in hosts. Immune-related gene expressions of cytokines including IL-10, IL-1β, TNF-α, IFN-γ in the livers, spleens, HK, and intestines were up-regulated significantly. Besides, a more potent phagocytosis response was observed in immunized fish, and higher survival rates were presented in immunized with Lc-pPG1-Aha1 (60%) and Lc-pPG2-Aha1 (50%) after re-infection with virulent strain . Moreover, the recombinant were shown a stronger propensity for survivability in the intestine in immunized fish. Taken together, the recombinant strains might be promising candidates for oral vaccination against infections in common carps.
Topics: Aeromonas hydrophila; Animals; Bacterial Vaccines; Carps; Lacticaseibacillus casei; Vaccination
PubMed: 35499101
DOI: 10.1080/21505594.2022.2063484 -
Pathogens (Basel, Switzerland) May 2023Virulent (vAh) strains that cause motile septicemia (MAS) in farmed channel catfish () have been an important problem for more than a decade. However, the routes of...
Virulent (vAh) strains that cause motile septicemia (MAS) in farmed channel catfish () have been an important problem for more than a decade. However, the routes of infection of vAh in catfish are not well understood. Therefore, it is critical to study the pathogenicity of vAh in catfish. To this goal, a new bioluminescence expression plasmid (pAK3) with the chloramphenicol acetyltransferase () gene was constructed and mobilized into vAh strain ML09-119, yielding bioluminescent vAh (BvAh). After determining optimal chloramphenicol concentration, plasmid stability, bacteria number-bioluminescence relationship, and growth kinetics, the catfish were challenged with BvAh, and bioluminescent imaging (BLI) was conducted. Results showed that 5 to 10 µg/mL chloramphenicol was suitable for stable bioluminescence expression in vAh, with some growth reduction. In the absence of chloramphenicol, vAh could not maintain pAK3 stably, with the half-life being 16 h. Intraperitoneal injection, immersion, and modified immersion (adipose fin clipping) challenges of catfish with BvAh and BLI showed that MAS progressed faster in the injection group, followed by the modified immersion and immersion groups. BvAh was detected around the anterior mouth, barbels, fin bases, fin epithelia, injured skin areas, and gills after experimental challenges. BLI revealed that skin breaks and gills are potential attachment and entry portals for vAh. Once vAh breaches the skin or epithelial surfaces, it can cause a systemic infection rapidly, spreading to all internal organs. To our best knowledge, this is the first study that reports the development of a bioluminescent vAh and provides visual evidence for catfish-vAh interactions. Findings are expected to provide a better understanding of vAh pathogenicity in catfish.
PubMed: 37242340
DOI: 10.3390/pathogens12050670 -
Antibiotics (Basel, Switzerland) Jul 2022The overuse or abuse of antimicrobial drugs in aquaculture, aggravates the generation of drug-resistant bacteria, which has caused potential risks to human health and...
The overuse or abuse of antimicrobial drugs in aquaculture, aggravates the generation of drug-resistant bacteria, which has caused potential risks to human health and the aquaculture industry. Flavonoid-antibiotic combinations have been shown to suppress the emergence of resistance in bacteria, and sometimes even reverse it. Here, the antibacterial activity of florfenicol in combination with quercetin, a potential drug to reverse multidrug resistance, was tested against (. ). Of eleven selected antimicrobial agents, quercetin and florfenicol showed the strongest bactericidal effect, and fractional inhibitory concentration (FIC) indices were 0.28, showing a highly synergistic effect. Then, the antibacterial activities of quercetin and florfenicol against were further tested in vitro and in vivo. Bacterial viability of decreased in a florfenicol dose-dependent manner, about 16.3-191.4-fold lower in the presence of 15 μg/mL quercetin and 0.156 to 1.25 μg/mL florfenicol than in the absence of quercetin, respectively. The cell killing was maximum at 45 μg/mL quercetin in the dose range tested plus 0.156 μg/mL florfenicol. The viability decreased over time during the combined treatment with quercetin and florfenicol by 60.5- and 115-fold in 0.156 μg/mL florfenicol and 0.625 μg/mL florfenicol, respectively. Additionally, the synergistic effect was confirmed by the bacterial growth curve. Furthermore, quercetin and florfenicol had an obvious synergistic activity in vivo, reducing the bacterial load in the liver, spleen and kidney tissues of up to 610.6-fold compared with the florfenicol group, and improving the survival rate of infected fish from 10% in the control group to 90% in drug combinations group. These findings indicated that quercetin could potentiate the antibacterial activity of florfenicol against infection and may reduce the use of antimicrobial drugs and improve the prevention and control capability of bacterial resistance.
PubMed: 35884183
DOI: 10.3390/antibiotics11070929