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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 -
Frontiers in Immunology 2022are autochthonous bacteria of aquatic environments that are considered to be emerging pathogens to humans, producing diarrhea, bacteremia, and wound infections. Genetic...
are autochthonous bacteria of aquatic environments that are considered to be emerging pathogens to humans, producing diarrhea, bacteremia, and wound infections. Genetic identification shows that 95.4% of the strains associated with clinical cases correspond to the species (37.26%), (23.49%), (21.54%), and (13.07%). However, few studies have investigated the human immune response against some spp. such as , , and . The present study aimed to increase the knowledge about the innate human immune response against six species, using, for the first time, an infection model with the monocytic human cell line THP-1, and to evaluate the intracellular survival, the cell damage, and the expression of 11 immune-related genes (, , , , , , , , , , and ). Transcriptional analysis showed an upregulated expression of a variety of the monocytic immune-related genes, with a variable response depending upon the species. The species that produced the highest cell damage, independently of the strain origin, coincidentally induced a higher expression of immune-related genes and corresponded to the more prevalent clinical species , , and . Additionally, monocytic cells showed an overexpression of the apoptotic and pyroptotic genes involved in cell death after , , and infection. However, the apoptosis route seemed to be the only way of producing cell damage and death in the case of the species and , while apparently only used the pyroptosis route.
Topics: Aeromonas; Aeromonas hydrophila; Cell Line; Gram-Negative Bacterial Infections; Humans; Immunity
PubMed: 35874671
DOI: 10.3389/fimmu.2022.875689 -
Veterinary World Jan 2017This study was conducted to evaluate the presence of spp. in raw and ready-to-eat (RTE) fish commonly consumed in Assiut city, Egypt, and to determine virulence factors...
AIM
This study was conducted to evaluate the presence of spp. in raw and ready-to-eat (RTE) fish commonly consumed in Assiut city, Egypt, and to determine virulence factors due to they play a key role in their pathogenicity.
MATERIALS AND METHODS
A total of 125 samples of raw and RTE fish samples were taken from different fish markets and fish restaurants in Assiut Governorate and screened for the presence of spp. by enrichment on tryptic soy broth then incubated at 30°C for 24 h. Plating unto the sterile Petri dishes containing agar base to which selective supplement was added. The plates were incubated at 37°C for 24 h. Presumptive colonies were biochemically confirmed and analyzed for pathogenicity by hemolysin production, protease, and lipase detection.
RESULTS
The results indicated that raw fish were contaminated with spp. (40% in wild and 36% in cultured Nile tilapia). Regarding RTE, spp. could be isolated with the percentage of 16%, 28% and 20% in fried Bolti, grilled Bolti and fried Bayad, respectively. Out of 35 isolates obtained, 22 were categorized as , 12 were classified as and were found in only one isolate. The virulence factors of spp. were detected and the results showed that all isolates produced of hemolysin (91.4%), protease (77.1%), and lipase enzyme (17.1%).
CONCLUSION
This study indicates that the presence of with virulence potential in fresh and RTE fish may be a major threat to public health.
PubMed: 28246446
DOI: 10.14202/vetworld.2017.34-37 -
Food Science & Nutrition Feb 2020, an inhabitant in the aquatic ecosystem is considered as an important foodborne bacterial zoonotic pathogen in aquaculture. The present study aimed to identify virulent...
, an inhabitant in the aquatic ecosystem is considered as an important foodborne bacterial zoonotic pathogen in aquaculture. The present study aimed to identify virulent from naturally infected in river Cauvery and in vitro evaluation of shrimp chitosan. Rimler Shotts (RS) and blood agar medium identified the presence of pathogenic sp. from the infected . Ah17 was identified using 16S rRNA nucleotide sequence. Extracellular enzymes such as amylase, lipase, and protease were screened in Ah17. Antibiotic susceptibility tests showed Ah17 was highly resistant against -lactam, glycopeptide, macrolides, phosphonic, fucidin, and oxazolidinone classes of antibiotics. Virulent genes such as hemolysin ( and , heat-labile enterotoxin (), cytotonic heat-stable enterotoxin (), elastase (), and lipase () were identified. Growth and the viable cell population of virulent Ah17 were significantly reduced in a dose-dependent manner against shrimp chitosan (CHS) from (). Thus, the present study isolated virulent Ah17 from the environmental source and characterized in vitro with shrimp chitosan.
PubMed: 32148833
DOI: 10.1002/fsn3.1416 -
Virulence Dec 2022The molecular mechanisms underlying -pathogenesis are not well understood. Using head kidney macrophages (HKM) of , we previously reported the role of ER-stress in...
The molecular mechanisms underlying -pathogenesis are not well understood. Using head kidney macrophages (HKM) of , we previously reported the role of ER-stress in -induced pathogenesis. Here, we report that PI3K/PLC-induced cytosolic-Ca imbalance induces the expression of pro-apoptotic ER-stress marker, CHOP in infected HKM. CHOP promotes HKM apoptosis by inhibiting AKT activation and enhancing JNK signaling. Elevated mitochondrial ROS (mtROS) was recorded which declined significantly by ameliorating ER-stress and in the presence of ER-Ca release modulators (2-APB and dantrolene) and mitochondrial-Ca uptake inhibitor, Ru360, together suggesting the role of ER-mitochondrial Ca dynamics in mtROS generation. Inhibiting mtROS production reduced HKM death implicating the pro-apoptotic role of mtROS in -pathogenesis. The expression of autophagic proteins (LC3B, beclin-1, and atg 5) was suppressed in the infected HKM. Our results with autophagy-inducer rapamycin demonstrated that impaired autophagy favored the cytosolic accumulation of mitochondrial DNA (mtDNA) and the process depended on mtROS levels. Enhanced caspase-1 activity and IL-1β production was detected and transfection studies coupled with pharmacological inhibitors implicated mtROS/mtDNA axis to be crucial for activating the caspase-1/IL-1β cascade in infected HKM. RNAi studies further suggested the involvement of IL-1β in generating pro-apoptotic NO in -infected HKM. Our study suggests a novel role of ER-mitochondria cross-talk in regulating pathogenesis. Based on our observations, we conclude that induces ER-stress and inhibits mitophagy resulting in mitochondrial dysfunction which leads to mtROS production and translocation of mtDNA into cytosol triggering the activation of caspase-1/IL-1β-mediated NO production, culminating in HKM apoptosis.
Topics: Aeromonas hydrophila; Animals; Apoptosis; Autophagy; Caspase 1; Cytosol; DNA, Mitochondrial; Interleukin-1beta; Macrophages; Mitochondria; Nitric Oxide; Reactive Oxygen Species
PubMed: 34967692
DOI: 10.1080/21505594.2021.2018767 -
Frontiers in Immunology 2022In China, channel catfish () is an important aquaculture species; however, haemorrhagic disease ( induced disease) in these fish has caused tremendous economic loss due...
In China, channel catfish () is an important aquaculture species; however, haemorrhagic disease ( induced disease) in these fish has caused tremendous economic loss due to high morbidity and mass mortality in the breeding industry. The role of cortisol in bacterial diseases, particularly in the acute phase, remains unclear. In this study, liver transcriptome (RNA-seq) and chromatin accessibility (ATAC-seq) analyses were employed to investigate the early functional role of cortisol in -stimulated responses. Our experiments confirmed that infection can initially significantly increase serum cortisol levels at 1 h after infection. At this time point, the increased serum cortisol levels can significantly regulate -regulated genes by affecting both transcriptome and chromatin accessibility. Cross-analysis of RNA-seq and ATAC-seq revealed that a certain gene group (92 target_DEGs) was regulated at an early time point by cortisol. KEGG enrichment analysis revealed that the top three pathways according to target_DEGs were cancer, glutathione metabolism, and the Notch signalling pathway. The protein-protein interaction analysis of target_DEGs revealed that they may be primarily involved in cell proliferation, CD8 T cell function, glutathione synthesis, and activation of the NF-κB signalling pathway. This suggests that after the emergence of immune stress, the early regulation of cortisol is positive against the immune response. It is possible that in this situation, the animal is attempting to avoid dangerous situations and risks and then cope with the imbalance produced by the stressor to ultimately restore homeostasis. Our results will contribute to future research on fish and provide valuable insight regarding the mechanism of immune regulation by cortisol and the study of bacterial haemorrhagic disease in channel catfish.
Topics: Animals; Aeromonas hydrophila; Hydrocortisone; Transcriptome; Chromatin; Gram-Negative Bacterial Infections; Fish Diseases; Ictaluridae; Liver; Glutathione
PubMed: 36532002
DOI: 10.3389/fimmu.2022.989075 -
Microbiological Research Apr 2023Aeromonas hydrophila (Ah) is a zoonotic pathogen of great importance to aquaculture and human health. This study systematically evaluated the impact of salinity, sugar,...
Aeromonas hydrophila (Ah) is a zoonotic pathogen of great importance to aquaculture and human health. This study systematically evaluated the impact of salinity, sugar, ammonia nitrogen, and nitric nitrogen levels on the fitness of Ah by using Luria-Bertani (LB) broth supplemented with different concentrations of NaCl, sucrose, NHCl, urea, NaNO or NaNO. Results showed that the static biofilm formation of Ah was higher at 28 °C compared to 37 °C (P < 0.05). At 28 °C, as the NaCl (>1 %) and sucrose levels increased, the Ah biofilm formation and the binding between Ah cells and monoclonal antibodies (mAbs, for immunodetection) decreased. Elevated ammonia nitrogen and nitric nitrogen levels generated no significant impact on Ah biofilm formation or immunodetection (P > 0.05). The expression of mAbs-targeted Omp remained unchanged under high NaCl or sucrose conditions. Further analysis showed that high sucrose conditions led to the over-expression of the extracellular polysaccharides (PS) and promoted the formation of capsule-like structures. These over-expressed PS and capsule structures might be one reason explaining the inhibited immunodetection efficacy. Results generated from this study provide crucial insights for the design of recovery and detection protocols for Ah present in food or environmental samples.
Topics: Humans; Aeromonas hydrophila; Osmotic Pressure; Sodium Chloride; Ammonia; Biofilms; Sucrose
PubMed: 36689842
DOI: 10.1016/j.micres.2023.127301 -
Veterinary World May 2020This study aimed to examine the intestinal histopathological lesions and mucous cell responses in the entire intestines of Nile tilapia administered with GG (LGG)-mixed...
AIM
This study aimed to examine the intestinal histopathological lesions and mucous cell responses in the entire intestines of Nile tilapia administered with GG (LGG)-mixed feed, after challenge.
MATERIALS AND METHODS
Intestinal samples from fish fed with control normal diet or LGG-mixed feed (10 colony-forming unit [CFU]/g feed) with or without in phosphate-buffered saline challenge (7.46 × 10 CFU/mL/fish) were collected and processed for histopathological study. The mucous cell responses were evaluated using histochemistry, using Alcian blue (AB) at pH 2.5, AB at pH 1.0, and periodic acid-Schiff-AB at pH 2.5. The quantification of the intestinal mucous cell size and the staining character of each mucin type from the entire intestine were recorded and counted.
RESULTS
Histopathological study showed remarkable lesions only in the proximal intestine in fish infected with , while LGG-fed fish had less intestinal damage, perhaps resulting from heterophil infiltration. Furthermore, a significant (p<0.01) increase in mixed mucous cell numbers was observed mainly in the proximal intestine of all challenged fish, compared with normal diet-fed fish without challenge, and also in LGG-fed fish with challenge compared with LGG-fed fish without challenge.
CONCLUSION
Dietary LGG-fed Nile tilapia showed improvements in host innate immunity. In addition, LGG was effective in decreasing intestinal lesions from a-induced intestinal damage. Moreover, increasing numbers of mixed mucous cells in the proximal intestine might be indicative of certain pathological conditions in Nile tilapia after infection.
PubMed: 32636595
DOI: 10.14202/vetworld.2020.967-974 -
Frontiers in Microbiology 2018Virulent causes severe motile septicemia in warmwater fishes. In recent years, channel catfish farming in the U.S.A. and carp farming in China have been affected by...
Virulent causes severe motile septicemia in warmwater fishes. In recent years, channel catfish farming in the U.S.A. and carp farming in China have been affected by virulent , and genome comparisons revealed that these virulent strains belong to the same clonal group. Bacterial secretion systems are often important virulence factors; in the current study, we investigated whether secretion systems contribute to the virulent phenotype of these strains. Thus, we conducted comparative secretion system analysis using 55 genomes, including virulent strains from U.S.A. and China. Interestingly, tight adherence (TaD) system is consistently encoded in all the vAh strains. The majority of U.S.A. isolates do not possess a complete type VI secretion system, but three core elements [ (), , and ()] are encoded. On the other hand, Chinese isolates have a complete type VI secretion system operon. None of the virulent isolates have a type III secretion system. Deletion of two genes encoding type VI secretion system proteins ( and ) from virulent isolate ML09-119 reduced virulence 2.24-fold in catfish fingerlings compared to the parent strain ML09-119. By determining the distribution of genes encoding secretion systems in strains, our study clarifies which systems may contribute to core functions and which may contribute to more specialized adaptations such as virulence. Our study also clarifies the role of type VI secretion system in virulence.
PubMed: 30687246
DOI: 10.3389/fmicb.2018.03216 -
International Journal of Molecular... Sep 2022is an important pathogen that mainly harms aquatic animals and has exhibited resistance to a variety of antibiotics. Here, to seek an effective alternative for...
is an important pathogen that mainly harms aquatic animals and has exhibited resistance to a variety of antibiotics. Here, to seek an effective alternative for antibiotics, the effects of umbelliferone (UM) at sub-MICs on virulence factors and the quorum-sensing system were studied. Subsequently, RNA sequencing was employed to explore the potential mechanisms for the antivirulence activity of umbelliferone. Meanwhile, the protective effect of umbelliferone on grass carp infected with was studied in vivo. Our results indicated that umbelliferone could significantly inhibit virulence such as hemolysis, biofilm formation, swimming and swarming motility, and their quorum-sensing signals AHL and AI-2. Transcriptomic analysis showed that umbelliferone downregulated expression levels of genes related to exotoxin, the secretory system (T2SS and T6SS), iron uptake, etc. Animal studies demonstrated that umbelliferone could significantly improve the survival of grass carps infected with , reduce the bacterial load in the various tissues, and ameliorate cardiac, splenic, and hepatopancreas injury. Collectively, umbelliferone can reduce the pathogenicity of and is a potential drug for treating infection.
Topics: Aeromonas hydrophila; Animals; Anti-Bacterial Agents; Carps; Exotoxins; Fish Diseases; Gram-Negative Bacterial Infections; Iron; Umbelliferones; Virulence Factors
PubMed: 36232424
DOI: 10.3390/ijms231911119