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Brazilian Journal of Microbiology :... Sep 2020This study was aimed to understand the expression of miR-146a in zebrafish (Danio rerio) and its role in regulating immune responses during Aeromonas hydrophila and...
This study was aimed to understand the expression of miR-146a in zebrafish (Danio rerio) and its role in regulating immune responses during Aeromonas hydrophila and Edwardsiella piscicida infections. The miR-146a expression was observed from the 1-h post fertilization (hpf) stage and gradually increased up to the early larval stage of zebrafish. The ubiquitous expression of miR-146a was detected in all tested tissues, with the highest level in gills. The expression of miR-146a was significantly increased in larvae when exposed to E. piscicida infection at 24 and 48 h post exposure (hpe). Intraperitoneally (i.p.) injected A. hydrophila and E. piscicida into adult zebrafish showed significant upregulation of miR-146a in gills. Furthermore, immune-related genes, toll-like receptor, tlr-4, transducing signaling pathway molecules, traf-6 and myd88 (bacteria-infected larvae and adults), transcription factor relA and mcp-1b (bacteria-infected adults), pro-inflammatory, il-6 (A. hydrophila-exposed larvae) and mmp-9 (bacteria-exposed larvae) were significantly repressed. In contrast, il-1β, tnf-α, cxcl-18b, and ccl-34a.4 were induced in both bacteria-challenged larvae and adults. Based on the results, it is suggested that endogenous miR-146a could act as an infection inducible miRNA in zebrafish upon A. hydrophila and E. piscicida infections; also, it could potentially regulate the immune responses in zebrafish.
Topics: Aeromonas hydrophila; Animals; Edwardsiella; Fish Diseases; Gene Expression Regulation; Gram-Negative Bacterial Infections; Immunity; Life Cycle Stages; MicroRNAs; Zebrafish
PubMed: 32067211
DOI: 10.1007/s42770-020-00237-w -
Frontiers in Microbiology 2022, a ubiquitous bacterium in aquatic habitats with broad host ranges, has earned the nickname of a 'Jack-of-all-trades'. However, there is still a limited understanding...
, a ubiquitous bacterium in aquatic habitats with broad host ranges, has earned the nickname of a 'Jack-of-all-trades'. However, there is still a limited understanding of the mechanism of how this bacterium fit the competition with other species in dynamic surroundings. The type VI secretion system (T6SS) is macromolecular machinery found in Gram-negative bacteria's cell envelope that is responsible for bacterial killing and/or pathogenicity toward different host cells. In this study, the depression of T6SS under iron-limiting conditions was detected. The ferric uptake regulator (Fur) was then found to act as an activator of T6SS by directly binding to the Fur box region in A promoter in the T6SS gene cluster. The transcription of A was repressed in Δ. Moreover, the inactivation of Fur resulted in considerable defects in the interbacterial competition activity and pathogenicity of and . These findings provide the first direct evidence that Fur positively regulates the expression and functional activity of T6SS in Gram-negative bacteria and will help to understand the fascinating mechanism of competitive advantage for in different ecological niches.
PubMed: 36845974
DOI: 10.3389/fmicb.2022.1099611 -
Microbiology Spectrum Feb 2023Hypervirulent Aeromonas hydrophila (vAh) has emerged as the etiologic agent of epidemic outbreaks of motile septicemia (MAS) in high-density aquaculture of farmed carp...
A Global Survey of Hypervirulent Aeromonas hydrophila (vAh) Identified vAh Strains in the Lower Mekong River Basin and Diverse Opportunistic Pathogens from Farmed Fish and Other Environmental Sources.
Hypervirulent Aeromonas hydrophila (vAh) has emerged as the etiologic agent of epidemic outbreaks of motile septicemia (MAS) in high-density aquaculture of farmed carp in China and catfish in the United States, which has caused millions of tons of lost fish. We conducted a global survey to better understand the evolution, geographical distribution, and phylogeny of vAh. isolates were isolated from fish that showed clinical symptoms of MAS, and pure cultures were screened for the ability to utilize -inositol as the sole carbon source. A total of 113 inositol-utilizing bacterial strains were included in this study, including additional strains obtained from previously published culture collections. Based on a phylogeny, this collection included 66 A. hydrophila isolates, 48 of which were vAh. This collection also included five new vAh isolates from diseased Pangas catfish (Pangasius pangasius) and striped catfish (Pangasianodon hypophthalmus) obtained in Cambodia and Vietnam, respectively. Genome sequences were generated from representative vAh and non-vAh isolates to evaluate the potential for lateral genetic transfer of the inositol catabolism pathway. Phylogenetic analyses of each of the nine genes required for -inositol utilization revealed the close affiliation of vAh strains regardless of geographic origin and suggested lateral genetic transfer of this catabolic pathway from an Enterobacter species. Prediction of virulence factors was conducted to determine differences between vAh and non-vAh strains in terms of virulence and secretion systems. Core genome phylogenetic analyses on vAh isolates and spp. disease isolates (55 in total) were conducted to evaluate the evolutionary relationships among vAh and other sp. isolates, which supported the clonal nature of vAh isolates. This global survey of vAh brought together scientists that study fish disease to evaluate the evolution, geographical distribution, phylogeny, and hosts of vAh and other sp. isolates. In addition to vAh isolates from China and the United States, four new vAh isolates were isolated from the lower Mekong River basin in Cambodia and Vietnam, indicating the significant threat of vAh to modern aquaculture and the need for improved biosecurity to prevent vAh spread.
PubMed: 36815836
DOI: 10.1128/spectrum.03705-22 -
Antioxidants (Basel, Switzerland) Nov 2022The oxidative stress facing fish during intensive production brings about diseases and mortalities that negatively influence their performance. Along with that, the...
Impacts of Fortifying Nile Tilapia () Diet with Different Strains of Microalgae on Its Performance, Fillet Quality and Disease Resistance to Considering the Interplay between Antioxidant and Inflammatory Response.
The oxidative stress facing fish during intensive production brings about diseases and mortalities that negatively influence their performance. Along with that, the increased awareness of omega-3 polyunsaturated fatty acids (omega-3-PUFAs) health benefits has been triggered the introduction of alternative additives in aqua feed that cause not only modulation in fish immune response but also fortification of their fillet. In this context, the role of microalgae mix (NSS) containing Nannochloropsis oculate and Schizochytrium and Spirulina species, which were enriched with bioactive molecules, especially EPA and DHA, was assessed on Nile tilapia's performance, fillet antioxidant stability, immune response, and disease resistance. Varying levels of NSS (0.75, 1.5, and 3%) were added to Nile tilapia's diet for 12 weeks and then a challenge of fish with virulent Aeromonas hydrophila (A. hydrophila) was carried out. Results showed that groups fed NSS, especially at higher levels, showed an improved WG and FCR, which corresponded with enhanced digestive enzymes' activities. Higher T-AOC was detected in muscle tissues of NSS. fed fish with remarkable reduction in ROS, HO, and MDA contents, which came in parallel with upregulation of GSH-Px, CAT, and SOD genes. Notably, the contents of EPA and DHA in fillet were significantly increased with increasing the NSS levels. The mean log counts of pathogenic Vibrio and Staphylococcus species were reduced, and conversely, the populations of beneficial Lactobacillus and Bacillus species were increased more eminent after supplementation of NSS. and NSS.. Moreover, regulation of the immune response (lysozyme, IgM, ACH50, NO, and MPO), upregulation of , , and , and downregulation of , , ,and were observed following dietary higher NSS levels. After challenge, reduction in A. hydrophila counts was more prominent, especially in NSS. supplemented group. Taken together, the current study encourages the incorporation of such microalgae mix in Nile tilapia's diet for targeting maximum performance, superior fillet quality, and protection against A. hydrophila.
PubMed: 36358553
DOI: 10.3390/antiox11112181 -
Animals : An Open Access Journal From... Feb 2021was isolated from an African black-footed penguin () that died while in zoo captivity. At necropsy, the virulence of appeared to be enhanced by stress, so was assessed...
was isolated from an African black-footed penguin () that died while in zoo captivity. At necropsy, the virulence of appeared to be enhanced by stress, so was assessed in the presence of in vitro and in vivo stressors and serial passaging in mice. Virulence genes from the isolate were amplified by PCR. In vitro assays were conducted to test the hemolytic activity, cytotoxicity, and effect of stress hormones on virulence. In vivo assays were conducted to test the stress effect on mortality of -infected mice and virulence in mice. Two virulence genes coding for hemolysin () and aerolysin () were detected, and the cytotoxic potential of the isolate was demonstrated in baby hamster kidney and Vero cells. Some or all mice inoculated with and exposed to stress hormones (epinephrine and norepinephrine) or low temperature died, while mice inoculated with and exposed to fasting or agitation stressors or no stressors survived. We concluded that stress can be fatal in mice experimentally infected with and that serial passaging in mice dramatically enhances the virulence of .
PubMed: 33669173
DOI: 10.3390/ani11020508 -
PloS One 2024Aeromonas hydrophila is one of the major pathogenic bacteria responsible for causing severe outbreaks at fish farms and is also a major global public health concern....
Aeromonas hydrophila is one of the major pathogenic bacteria responsible for causing severe outbreaks at fish farms and is also a major global public health concern. This bacterium harbors many virulence genes. The current study was designed to evaluate the antidrug and virulence potential of A. hydrophila by amplifying its antimicrobial resistance and virulence genes using PCR and examining their effects on fish tissues and organs. A total of 960 fish samples of Channa marulius and Sperata sarwari were collected from four sites of the rivers of the Punjab, Pakistan. A. hydrophila isolates were subjected to biochemical identification and detection of virulence and antimicrobial resistance (AMR) genes by PCR. We retrieved 181 (6.46%) A. hydrophila isolates from C. marulius and 177 (6.25%) isolates from S. sarwari. Amplification through PCR revealed the incidence of virulence genes in 95.7% of isolates in C. marulius and 94.4% in S. sarwari. Similarly, amplification through PCR also revealed occurrence of AMR genes in 87.1% of isolates in C. marulius and 83.9% in S. sarwari. Histopathological examination revealed congestion (5.2%) and hepatocyte necrosis (4.6%) in liver, lamellar fusion (3.3%) and the presence of bacterial colonies (3.7%) in gills, fin erosion (6%), and the presence of biofilms (3.5%) in tail fins of infected fish. Phylogenetic tree analysis of 16S rRNA and gyrB gene of A. hydrophila revealed 100% and 97% similarity, respectively, with 16S rRNA gene and gyrB of A. hydrophila isolated in previous studies. The results of antimicrobial susceptibility testing showed that all isolates demonstrated resistance to sulfamethoxazole, ampicillin, neomycin, and norfloxacin, while susceptibility to gentamicin, chloramphenicol, and tetracycline, and intermediate resistance was observed against cefotaxime. The results concluded that examined fish samples were markedly contaminated with virulent and multidrug strains of A. hydrophila which may be of a potential health risk. The study emphasizes the responsible antimicrobial use in aquaculture and the urgent need for effective strategies to control the spread of virulence and antimicrobial resistance genes in A. hydrophila.
Topics: Animals; Aeromonas hydrophila; Phylogeny; Pakistan; RNA, Ribosomal, 16S; Anti-Bacterial Agents; Catfishes; Aeromonas; Gram-Negative Bacterial Infections
PubMed: 38551906
DOI: 10.1371/journal.pone.0297979 -
Biomedicines Feb 2022The antimicrobial multidrug resistance (AMR) of pathogenic bacteria towards currently used antibiotics has a remarkable impact on the quality and prolongation of human...
The antimicrobial multidrug resistance (AMR) of pathogenic bacteria towards currently used antibiotics has a remarkable impact on the quality and prolongation of human lives. An effective strategy to fight AMR is the method PhotoDynamic Therapy (PDT). PDT is based on a joint action of a photosensitizer, oxygen, and light within a specific spectrum. This results in the generation of singlet oxygen and other reactive oxygen species that can inactivate the pathogenic cells without further regrowth. This study presents the efficacy of a new Pd(II)- versus Zn(II)-phthalocyanine complexes with peripheral positions of methylpyridiloxy substitution groups (pPdPc and ZnPcMe) towards Gram-negative bacteria (). Zn(II)-phthalocyanine, ZnPcMe was used as a reference compound for studies, bacause it is well-known with a high photodynamic inactivation ability for different pathogenic microorganisms. The studied new isolates of were antibiotic-resistant (R) and sensitive (S) strains. The photoinactivation results showed a full effect with 8 µM pPdPc for S strain and with 5 µM ZnPcMe for both R and S strains. Comparison between both new isolates of (S and R) suggests that the uptakes and more likely photoinactivation efficacy of the applied phthalocyanines are independent of the drug sensitivity of the studied strains.
PubMed: 35203593
DOI: 10.3390/biomedicines10020384 -
Foods (Basel, Switzerland) Sep 2020The antimicrobial efficacy of novel photodynamic inactivation and nanobubble technologies was evaluated against and as two important aquatic microbial pathogens....
The antimicrobial efficacy of novel photodynamic inactivation and nanobubble technologies was evaluated against and as two important aquatic microbial pathogens. Photodynamic inactivation results showed that LED (470 nm) and UV-A (400 nm)-activated curcumin caused a complete reduction in at 4 and 22 °C, and a greater than 2 log cfu/mL reduction in , which was curcumin concentration-dependent ( < 0.05). Furthermore, the photodynamic approach caused a greater than 6 log cfu/mL reduction and more than 4 log cfu/mL of reduction in aquaponic water samples ( < 0.05). Our results with the nanobubble technology showed that the nanobubbles alone did not significantly reduce bacteria ( > 0.05). However, a greater than 6 log cfu/mL reduction and a greater than 3 log cfu/mL of reduction were achieved when nanobubble technology was combined with ultrasound ( < 0.05). The findings described in this study illustrate the potential of applying photodynamic inactivation and nanobubble-ultrasound antimicrobial approaches as alternative novel methods for inactivating fish and shellfish pathogens.
PubMed: 32947883
DOI: 10.3390/foods9091306 -
Journal of Infection and Public Health 2016Aeromonas hydrophila is a Gram-negative, oxidase-positive, facultative, anaerobic, opportunistic aquatic pathogen. A. hydrophila produces virulence factors, such as... (Review)
Review
Aeromonas hydrophila is a Gram-negative, oxidase-positive, facultative, anaerobic, opportunistic aquatic pathogen. A. hydrophila produces virulence factors, such as hemolysins, aerolysins, adhesins, enterotoxins, phospholipase and lipase. In addition to isolation from aquatic sources, A. hydrophila has been isolated from meat and meat products, milk and dairy products, and vegetables. However, various studies showed that this opportunistic pathogen is resistant to commercial antibiotics. This is attributed to factors such as the indiscriminate use of antibiotics in aquaculture, plasmids or horizontal gene transfer. In this report, we highlight the occurrence, prevalence and antimicrobial resistance of A. hydrophila isolated from different food samples. The presence of antimicrobial-resistant A. hydrophila in food poses threats to public and aquatic animal health.
Topics: Aeromonas hydrophila; Animals; Anti-Bacterial Agents; Drug Resistance, Bacterial; Food Microbiology; Humans
PubMed: 26588876
DOI: 10.1016/j.jiph.2015.10.006 -
Veterinary Research Forum : An... Mar 2022is a bacterium associated with many diseases and disorders such as fin rot, skin ulcers and lethal hemorrhagic septicemia in fish. It bears several virulence factors...
is a bacterium associated with many diseases and disorders such as fin rot, skin ulcers and lethal hemorrhagic septicemia in fish. It bears several virulence factors including type III secretion system (TSS), , and enzymes ( , lipase) that seem to play an important role in its pathogenesis. Detection of virulence markers by polymerase chain reaction (PCR) is a key procedure in defining the patho-genic ability of pathogenic bacteria and preparing a vaccine for its treatment. In this sense, this study was aimed to determine the frequency of virulence genes in isolates obtained from infected cultured carps in Khuzestan province. Out of 200 moribund carps with septicemic symptoms, 125 isolates were belonged to the motile aeromonads and 59 isolates were identified as by biochemical methods. Finally, using PCR analysis, 31 isolates were identified as . Five virulence genes were detected in these isolates including , , and TSS () by specific primers. Results showed that 23 (74.19%), 18 (58.06%), 16 (51.61%), 13 (41.63%) and 10 (32.25%) isolates possessed , , , and T3SS genes, respectively. The results of the present study showed that among 31 isolates, only five isolates had all of dominant virulence genes Thirteen other isolates had genotypes including , The remaining isolates had at least one virulence gene. This study showed that determination of the virulence genes by PCR can be a reliable method to identify a potential pathogenic strain.
PubMed: 35601789
DOI: 10.30466/vrf.2020.115998.2761