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Archives of Microbiology May 2016In a study where the prevalence of Aeromonas in shellfish was analysed, three isolates of Aeromonas schubertii were identified, representing this the first report of... (Review)
Review
In a study where the prevalence of Aeromonas in shellfish was analysed, three isolates of Aeromonas schubertii were identified, representing this the first report of this species from mussels. This species was originally described in 1988 from strains isolated from extra-intestinal human infections and since then has been cited in only 18 occasions. For many years, A. schubertii was the only mannitol-negative species of the genus. However, three additional mannitol-negative species (Aeromonas simiae, Aeromonas diversa and Aeromonas australiensis) have been described. This, together with the fact that A. schubertii is a rare human pathogenic species, motivated the present study to characterize its biochemical behaviour and differentiation from the other mannitol-negative species. The molecular similarity (16S rRNA, rpoD and gyrB genes) of the strains, presence of virulence genes and antimicrobial resistance were determined. All A. schubertii strains showed the same phenotypic behaviour, i.e. they use citrate, are positive for lysine decarboxylase and DL-lactate, but negative for production of mannitol, indole and acid from sucrose and could be easily differentiated from other mannitol-negative species. All strains carried the aerA and lafA virulence genes and showed susceptibility to all antibiotics tested. Seafood could be a transmission route of this bacterium to humans.
Topics: Aeromonas; Animals; Anti-Bacterial Agents; Bivalvia; Carboxy-Lyases; Citric Acid; DNA Gyrase; DNA-Directed RNA Polymerases; Food Microbiology; Humans; Lactic Acid; RNA, Ribosomal, 16S; Sigma Factor; Species Specificity
PubMed: 26825089
DOI: 10.1007/s00203-016-1189-5 -
Pathogens (Basel, Switzerland) Aug 2021is the etiological pathogen of internal organ nodules in snakehead fish. Infections with produce a significant economic loss in aquaculture. Therefore, it is important...
is the etiological pathogen of internal organ nodules in snakehead fish. Infections with produce a significant economic loss in aquaculture. Therefore, it is important to examine the immune mechanisms by which snakeheads defend against infection. In this study, we established a hybrid snakehead infection model by intraperitoneal injection of that produced internal organ nodules. The splenic immune response of infected fish was examined at the transcriptome level by Illumina-seq analysis. Results showed 14,796 differentially expressed genes (DEGs) following infection, including 4441 up-regulated unigenes and 10,355 down-regulated unigenes. KEGG analysis showed 2084 DEGs to be involved in 192 pathways, 14 of which were immune-related. Twelve DEGs were used to validate quantitative real-time PCR results with RNA-seq data. Time-course expression analysis of six genes demonstrated modulation of the snakehead immune response by Furthermore, transcriptome analysis identified a substantial number of DEGs that were involved in the apoptosis signaling pathway. TUNEL analysis of infected spleens confirmed the presence of apoptotic cells. This study provided new information for a further understanding of the pathogenesis of in snakeheads, which can be used to prevent and possibly treat infections.
PubMed: 34451461
DOI: 10.3390/pathogens10080997 -
Journal of Fish Diseases Jan 2019Aeromonas schubertii is a major epidemiological agent that threatens cultured snakeheads (Channidae) and has caused great economic losses in fish-farming industries in...
Aeromonas schubertii is a major epidemiological agent that threatens cultured snakeheads (Channidae) and has caused great economic losses in fish-farming industries in China in recent years. In present study, a specific TaqMan minor groove binder (MGB) probe fluorescence real-time quantitative PCR (qPCR) assay was developed to rapidly detect and quantify A. schubertii. A pair of qPCR primers and a TaqMan MGB probe were selected from the rpoD gene, which were shown to be specific for A. schubertii. A high correlation coefficient (R = 0.9998) in a standard curve with a 103% efficiency was obtained. Moreover, the qPCR method's detection limit was as low as 18 copies/μl, which was 100 times more sensitive than that of conventional PCR. The detection results for the A. schubertii in pond water and fish tissue were consistent with those of the viable counts. Bacterial load changes detected by qPCR in different tissues of snakeheads infected with A. schubertii showed that the gills and intestines may be the entry for A. schubertii, and the spleen and kidney are major sites for A. schubertii replication. The established method in present study should be a useful tool for the early surveillance and quantitation of A. schubertii.
Topics: Aeromonas; Animals; Bacterial Load; DNA Primers; Fish Diseases; Fishes; Fluorescence; Gram-Negative Bacterial Infections; Ponds; Real-Time Polymerase Chain Reaction; Sensitivity and Specificity; Water Microbiology
PubMed: 30474192
DOI: 10.1111/jfd.12911 -
Animals : An Open Access Journal From... Mar 2024is a pathogen that severely affects aquatic animals, including the snakehead, . Lytic bacteriophages have been recognized as effective alternatives to antibiotics for...
is a pathogen that severely affects aquatic animals, including the snakehead, . Lytic bacteriophages have been recognized as effective alternatives to antibiotics for controlling bacterial infections. However, there have been no reports of phages as far as we know. In this study, a lytic bacteriophage SD04, which could effectively infect , was isolated from pond water cultured with diseased snakehead. The SD04 phage formed small, round plaques on Petri dishes. Electron microscopy revealed a hexagonal head and a contractile tail. Based on its morphology, it may belong to the Myoviridae family. Two major protein bands with molecular weights of 50 and 38 kilodaltons were observed after the phage was subjected to SDS-PAGE. The phage showed a large average burst size, high specificity, and a broad host range. When stored at 4 °C, phage SD04 had high stability over 12 months and showed almost no variation within the first six months. All fish were healthy after both intraperitoneal injection and immersion administration of SD04, indicating the safety of the phage. After treatment with SD04, in both phage therapy groups and prevention groups showed high survival rates (i.e., 83.3 ± 3.3% and 100 ± 1.3%, respectively). Phage therapy inhibits bacterial growth in the liver, the target organ of the infected . The experimental results indicate the potential use of phage SD04 for preventing infection in .
PubMed: 38540055
DOI: 10.3390/ani14060957 -
Molecular Immunology Sep 2021As a proinflammatory cytokine of the interleukin-1 (IL-1) family, IL-18 plays important roles in host protection against bacterial, viral, and fungal infection. We...
As a proinflammatory cytokine of the interleukin-1 (IL-1) family, IL-18 plays important roles in host protection against bacterial, viral, and fungal infection. We cloned the open reading frame of snakehead (Channa argus) IL-18 (shIL-18) and found that it contained 609 base pairs and encoded 202 amino acid residues. The shIL-18 included a conserved IL-1-like family signature and two potential IL-1β-converting enzyme cutting sites; one was conserved in all analyzed IL-18s, but the other was unique to shIL-18. Unlike other IL-18s, shIL-18 also contained a predicted signal peptide. In this study, shIL-18 was constitutively expressed in all tested tissues, and its expression was induced by Aeromonas schubertii and Nocardia seriolae in the head kidney and spleen in vivo and by lipoteichoic acid, lipopolysaccharides, and polyinosinic-polycytidylic acid in head kidney leukocytes in vitro. Moreover, recombinant shIL-18 upregulated the expression of interferon-γ, IL-1β, and tumor necrosis factor-α1 and -α2 and promoted the proliferation of leukocytes. Taken together, these results showed that IL-18 played crucial roles in host defense against bacterial infection in fish, as it does in mammals.
Topics: Aeromonas; Animals; Cloning, Molecular; Fish Diseases; Fish Proteins; Fishes; Gram-Negative Bacterial Infections; Head Kidney; Interleukin-18; Lipopolysaccharides; Nocardia; Nocardia Infections; Spleen; Teichoic Acids
PubMed: 34280771
DOI: 10.1016/j.molimm.2021.07.013 -
Comparative Biochemistry and... 2021Mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase 3 (MEKK3) is a serine/threonine protein kinase that acts as a key regulator and is...
MEKK3 in hybrid snakehead (Channa maculate ♀ ×Channa argus ♂): Molecular characterization and immune response to infection with Nocardia seriolae and Aeromonas schubertii.
Mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase 3 (MEKK3) is a serine/threonine protein kinase that acts as a key regulator and is widely involved in various innate and acquired immune signaling pathways. In this study, we first cloned the complete open reading frame (ORF) of the MEKK3 gene (named CcMEKK3) in a hybrid snakehead (Channa maculate ♀ × Channa argus ♂). The full-length ORF of CcMEKK3 is 1851 bp, and encodes a putative protein of 616 amino acids containing a serine/threonine kinase catalytic (S-TKc) domain and a Phox and Bem1p (PB1) domain. A sequence alignment and phylogenetic tree analysis showed that CcMEKK3 is highly conserved relative to the MEKK3 proteins of other teleost species. CcMEKK3 was constitutively expressed in all the healthy hybrid snakehead tissues tested, with greatest expression in the immune tissues, such as the head kidney and spleen. The expression of CcMEKK3 was usually upregulated in the head kidney, spleen, and liver at different time points after infection with Nocardia seriolae or Aeromonas schubertii. Similarly, the dynamic expression levels of CcMEKK3 in head kidney leukocytes after stimulation revealed that CcMEKK3 was induced by LTA, LPS, and poly(I:C). In the subcellular localization analysis, CcMEKK3 was evenly distributed in the cytoplasm of HEK293T cells, and its overexpression significantly promoted the activities of NF-κB and AP-1. These results suggest that CcMEKK3 is involved in the immune defense against these two pathogens, and plays a crucial role in activating the NF-κB and MAPK signaling pathways.
Topics: Aeromonas; Animals; Fish Diseases; Fish Proteins; Fishes; Gram-Negative Bacterial Infections; Immunity, Innate; MAP Kinase Kinase Kinase 3; Nocardia; Nocardia Infections
PubMed: 34186154
DOI: 10.1016/j.cbpb.2021.110643 -
Microbial Pathogenesis Dec 2020Retrospective diagnosis of a bacterial collection (n = 31) originated from five farms reportedly affected by early mortality syndrome (EMS) in Southeast Asia in 2016...
Retrospective diagnosis of a bacterial collection (n = 31) originated from five farms reportedly affected by early mortality syndrome (EMS) in Southeast Asia in 2016 revealed that 9/31 isolates from two farms tested positive for V. parahaemolyticus causing acute hepatopancreatic necrosis disease (VP). Molecular analysis of the 22 remaining isolates showed that 21 isolates belong to Vibrio species including VP, V. vulnificus, V. cholerae, V. owensii and V. alginolyticus. One isolate from an AHPND farm was preliminarily identified as Aeromonas schubertii based on 99.43% nucleotide identity of 16S rRNA to the reference strain ATCC 43700 (X60416). Diseases caused by Vibrio bacteria have been well-studied in shrimp while pathogenic potential of non-Vibrio species has been relatively overlooked. Since the description of A. schubertii present in shrimp farms is rare, this study therefore focused on species identification and its pathogenic potential to shrimp based on a combination of multiple approaches i.e. multilocus sequence analysis (MLSA), challenge test, histopathology and in situ hybridization (ISH). Based on MLSA of 2464 bp derived from 16S rRNA (1346 bp), gyrB (568 bp) and rpoB (550 bp), this isolate was confirmed as A. schubertii. Immersion challenge using three successive 10-fold serial dilutions (2 × 10 to 2 × 10 CFU/mL) revealed that A. schubertii was pathogenic to shrimp and cumulative mortalities were dose-dependent (45-70%). The diseased shrimp exhibited gross sign of reddish body and remarkable histopathological lesion of collapsed hepatopancreatic tubules and typical encapsulation. ISH using A. schubertii-specific probe confirmed localization of bacteria in the hepatopancreas of the infected shrimp. In summary, this study reported a novel pathogenic, non-Vibrio species, A. schubertii recovered from an AHPND-affected farm causing up to 70% mortality in immersion challenge. Since A. schubertii is relatively new to shrimp, this may pose a potential risk for low salinity shrimp farming areas, active surveillance of this pathogen, therefore, should not be overlooked.
Topics: Aeromonas; Animals; Penaeidae; RNA, Ribosomal, 16S; Retrospective Studies; Vibrio; Vibrio parahaemolyticus
PubMed: 32950638
DOI: 10.1016/j.micpath.2020.104501 -
Microbiology Resource Announcements Jan 2022Aeromonas schubertii is a Gram-negative, rod-shaped bacterium. It is a rare species that has been reported in humans and aquatic animals. Here, we report the genome...
Aeromonas schubertii is a Gram-negative, rod-shaped bacterium. It is a rare species that has been reported in humans and aquatic animals. Here, we report the genome sequences of A. schubertii strains isolated from two mass mortality events in central Thailand that were associated with aquaculture of Asian seabass.
PubMed: 34989613
DOI: 10.1128/mra.01007-21 -
Journal of Fish Diseases Aug 2022Motile Aeromonas septicemia (MAS), a disease caused by Aeromonas spp., is recognized as a major disease in freshwater aquaculture. This study aimed to investigate the...
Motile Aeromonas septicemia (MAS), a disease caused by Aeromonas spp., is recognized as a major disease in freshwater aquaculture. This study aimed to investigate the distribution and diversity of Aeromonas spp. and their antimicrobial susceptibility patterns. A total of 86 isolates of Aeromonas spp. were recovered from diseased freshwater fishes from 13 farms in Thailand. All isolates were identified using biochemical characteristics, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), polymerase chain reaction assays, and the gyrB gene sequence analysis. The result of MALDI-TOF MS showed 100% (86 isolates) accuracy at genus-level identification, and 88.4% (76 isolates) accuracy at species-level identification. Six species of Aeromonas were confirmed through nucleotide sequencing and phylogenetic analysis of the gyrB gene Aeromonas veronii (72.1%), Aeromonas jandaei (11.6%), Aeromonas schubertii (9.3%), Aeromonas diversa (3.5%), Aeromonas hydrophila (2.3%), and Aeromonas punctata (1.2%). Antimicrobial susceptibility tests for all isolates revealed resistance against amoxicillin (99%), ampicillin (98%), oxolinic acid (81.4%), oxytetracycline (77%), trimethoprim-sulfamethoxazole (24%), and enrofloxacin (21%). The multiple antibiotic resistance (MAR) index varied between 0.14 and 0.86, with MAR values more than 0.2 in 99% of isolates. Furthermore, four diverse multidrug-resistant (MDR) patterns were found among Aeromonas isolates. Our finding show that A. veronii is the most abundant species in Thai cultured freshwater fish with the highest MDR patterns.
Topics: Aeromonas; Animals; Anti-Bacterial Agents; Fish Diseases; Fishes; Fresh Water; Microbial Sensitivity Tests; Phylogeny; Thailand
PubMed: 35598068
DOI: 10.1111/jfd.13650 -
Frontiers in Public Health 2021Aeromonads are aquatic bacteria associated with frequent outbreaks of diarrhea in coastal Bangladesh, but their potential risks from environmental sources have remained...
Aeromonads are aquatic bacteria associated with frequent outbreaks of diarrhea in coastal Bangladesh, but their potential risks from environmental sources have remained largely unexplored. This study, over 2 years, examined homestead pond waters in the region for monthly dynamics and diversity of spp. The bacterial counts showed bi-modal annual growth peak, pre- and post-monsoon, strongly correlating ( < 0.0005) with temperature. Of 200 isolates characterized, bv. sobria (27%) was predominant among co-existent (20%), (17%), (13%), and three more. PCR screening of virulence-related genes identified 15 genotypes (I to XV), however, enterotoxigenicity in animal model was observed for five genotypes, ca. 18% (nine of 50) strains, prevalent in bv. sobria, , and . Pathogenic strains were distinguishable by possessing at least three of the major virulence genes: , and , together with accessory virulence factors. PFGE of I-digested genomic DNA revealed high genetic diversity and distant lineage of potentially toxigenic clones. Therefore, along with increased global warming, spp. having multi-factorial virulence potential in coastal ponds that serve as drinking water sources pose a potential health risk, and underscores the need for routine monitoring.
Topics: Aeromonas; Animals; Bangladesh; Ponds; Virulence; Water
PubMed: 34307285
DOI: 10.3389/fpubh.2021.692166