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Microorganisms May 2023For a long time, the bacterial species seemed to be limited to a regrouping of psychrophilic subspecies that infect fish, particularly salmonids [...].
For a long time, the bacterial species seemed to be limited to a regrouping of psychrophilic subspecies that infect fish, particularly salmonids [...].
PubMed: 37317163
DOI: 10.3390/microorganisms11051189 -
Journal of Microbiology and... Oct 2020The emergence and spread of antimicrobial resistance in pathogenic bacteria of fish and shellfish have caused serious concerns in the aquaculture industry, owing to the... (Review)
Review
The emergence and spread of antimicrobial resistance in pathogenic bacteria of fish and shellfish have caused serious concerns in the aquaculture industry, owing to the potential health risks to humans and animals. Among these bacteria, , which is one of the most important primary pathogens in salmonids, is responsible for significant economic losses in the global aquaculture industry, especially in salmonid farming because of its severe infectivity and acquisition of antimicrobial resistance. Therefore, interest in the use of alternative approaches to prevent and control infections has increased in recent years, and several applications of bacteriophages (phages) have provided promising results. For several decades, and phages infecting this fish pathogen have been thoroughly investigated in various research areas including aquaculture. The general overview of phage usage to control bacterial diseases in aquaculture, including the general advantages of this strategy, has been clearly described in previous reviews. Therefore, this review specifically focuses on providing insights into the phages infecting , from basic research to biotechnological application in aquaculture, as well as recent advances in the study of .
Topics: Aeromonas salmonicida; Animals; Aquaculture; Bacterial Infections; Bacteriophages; Fish Diseases; Fishes
PubMed: 32807762
DOI: 10.4014/jmb.2005.05040 -
Diseases of Aquatic Organisms Jun 2016Aeromonas salmonicida is the oldest known infectious agent to be linked to fish disease and constitutes a major bacterial pathogen of fish, in particular of salmonids.... (Review)
Review
Aeromonas salmonicida is the oldest known infectious agent to be linked to fish disease and constitutes a major bacterial pathogen of fish, in particular of salmonids. This bacterium can be found almost worldwide in both marine and freshwater environments and has been divided into several sub-species. In this review, we present the most recent developments concerning our understanding of this pathogen, including how the characterization of new isolates from non-salmonid hosts suggests a more nuanced picture of the importance of the so‑called 'atypical isolates'. We also describe the clinical presentation regarding the infection across several fish species and discuss what is known about the virulence of A. salmonicida and, in particular, the role that the type 3 secretion system might play in suppressing the immune response of its hosts. Finally, isolates have displayed varied levels of antibiotic resistance. Hence, we review a number of solutions that have been developed both to prevent outbreaks and to treat them once they occur, including the application of pre- and probiotic supplements.
Topics: Aeromonas salmonicida; Animals; Fish Diseases; Fishes; Furunculosis; Gram-Negative Bacterial Infections
PubMed: 27304870
DOI: 10.3354/dao03006 -
Antibiotics (Basel, Switzerland) Aug 2022subsp. is a pathogenic bacterium responsible for furunculosis in salmonids. Following an outbreak of furunculosis, the infection can be treated with antibiotics, but...
subsp. is a pathogenic bacterium responsible for furunculosis in salmonids. Following an outbreak of furunculosis, the infection can be treated with antibiotics, but it is common to observe ineffective treatment due to antibiotic resistance. This bacterium has a wide variety of plasmids responsible for this resistance. Among them, pRAS3 carries a tetracycline resistance gene. Several variants of this plasmid have been discovered over the years (pRAS3-3432 and pRAS3.1 to 3.4). During the present study, two new variants of the plasmid pRAS3 were identified (pRAS3.5 and pRAS3-3759) in strains of subsp. . Plasmid pRAS3-3759, which has been found in many strains from the same region over the past three years, has an additional genetic element identical to one found in pRAS3-3432. This genetic element was also found in , a swine pathogen. In this study, we analyzed the bacteria's resistance to tetracycline, the number of copies of the plasmids, and the growth of the strains that carry five of the pRAS3 variants (pRAS3.3 to 3.5, pRAS3-3432, and pRAS3-3759). The results show no particular trend despite the differences between the plasmids, except for the resistance to tetracycline when analyzed in an isogenic background. Blast analysis also revealed the presence of pRAS3 plasmids in other bacterial species, which suggests that this plasmid family has widely spread. This study once again highlights the ability of subsp. to adapt to furunculosis antibiotic treatments, and the still-growing family of pRAS3 plasmids.
PubMed: 36009916
DOI: 10.3390/antibiotics11081047 -
Microorganisms Nov 2023The plasmid known as pAsa5 is present in subsp. , a fish pathogen. The pAsa5 plasmid carries genes that are essential for the bacterium's virulence. Recombination...
The plasmid known as pAsa5 is present in subsp. , a fish pathogen. The pAsa5 plasmid carries genes that are essential for the bacterium's virulence. Recombination events are known to occur in pAsa5, resulting in the loss of certain segments or the acquisition of additional genetic elements. For example, the transposon carried by the large pAsa8 plasmid was found to be inserted into the pAsa5 plasmid in the SHY16-3432 strain, enabling the addition of antibiotic resistance genes to this plasmid, which does not normally possess any. In this study, we present the isolation of additional strains carrying pAsa8. Further analyses of these strains revealed that a fusion between pAsa5 and the complete version of pAsa8 is possible. The pAsa8 transposon insertion in pAsa5 seen in the SHY16-3432 strain appears to be an aberrant event compared to the fusion of the two full-length plasmids. A 22-nucleotide sequence, present in both plasmids, serves as the site for the fusion of the two plasmids. Moreover, it is possible to introduce pAsa8 through conjugation into naive strains of subsp. and once the plasmid is within a new strain, the fusion with pAsa5 is detectable. This study reveals a previously unexplored aspect of pAsa5 plasmid biology, highlighting an additional risk for the spread of antibiotic resistance genes in subsp.
PubMed: 38004697
DOI: 10.3390/microorganisms11112685 -
IDCases 2019is a facultative Gram-negative bacillus, inhabiting in water. It is a common source of furunculosis and septicemia in fish. Report on the human infection with this...
is a facultative Gram-negative bacillus, inhabiting in water. It is a common source of furunculosis and septicemia in fish. Report on the human infection with this organism is rare. A male farmer referred with weakness and intermittent fever. He had cardiac valves' regurgitation due to fever with rheumatic heart disease. He had a history of swimming in well water. Transthoracic echocardiography (TTE) revealed a mobile mass of 1.3 × 0.9 cm attached to the mitral valve chordae, suggestive of a vegetation. was isolated from the blood. After cardiac surgery and taking ceftriaxone for 4 weeks, he was discharged in good general condition. Five previous case reports of human infection with this organism were found. The patient was the sixth human case, and the first endocarditis, reported with this organism. is a rare agent for human infection. Contact with water is a risk factor for this type of infection. It seems that the use of modern diagnostic methods has been effective in identifying the microorganism.
PubMed: 31485414
DOI: 10.1016/j.idcr.2019.e00625 -
Scientific Reports Aug 2017Phages infecting Aeromonas salmonicida subsp. salmonicida, the causative agent of the fish disease furunculosis, have been isolated for decades but very few of them have...
Phages infecting Aeromonas salmonicida subsp. salmonicida, the causative agent of the fish disease furunculosis, have been isolated for decades but very few of them have been characterized. Here, the host range of 12 virulent phages, including three isolated in the present study, was evaluated against a panel of 65 A. salmonicida isolates, including representatives of the psychrophilic subspecies salmonicida, smithia, masoucida, and the mesophilic subspecies pectinolytica. This bacterial set also included three isolates from India suspected of being members of a new subspecies. Our results allowed to elucidate a lytic dichotomy based on the lifestyle of A. salmonicida (mesophilic or psychrophilic) and more generally, on phage types (lysotypes) for the subspecies salmonicida. The genomic analyses of the 12 phages from this study with those available in GenBank led us to propose an A. salmonicida phage pan-virome. Our comparative genomic analyses also suggest that some phage genes were under positive selection and A. salmonicida phage genomes having a discrepancy in GC% compared to the host genome encode tRNA genes to likely overpass the bias in codon usage. Finally, we propose a new classification scheme for A. salmonicida phages.
Topics: Aeromonas salmonicida; Bacteriophages; Base Composition; Genetic Variation; Genome, Viral; Host Specificity; India; Selection, Genetic
PubMed: 28765570
DOI: 10.1038/s41598-017-07401-7 -
Microorganisms Jan 2022is a global distributed Gram-negative teleost pathogen, affecting mainly salmonids in fresh and marine environments. strains are classified as typical or atypical...
is a global distributed Gram-negative teleost pathogen, affecting mainly salmonids in fresh and marine environments. strains are classified as typical or atypical depending on their origin of isolation and phenotype. Five subspecies have been described, where subsp. is the only typical subspecies, and the subsp. , , , and are considered atypical. Genomic differences between subsp. isolates and their relationship with the current classification have not been explored. Here, we sequenced and compared the complete closed genomes of four virulent strains to elucidate their molecular diversity and pathogenic evolution using the more accurate genomic information so far. Phenotypes, biochemical, and enzymatic profiles were determined. PacBio and MiSeq sequencing platforms were utilized for genome sequencing. Comparative genomics showed that atypical strains belong to the subsp. with 99.55% ± 0.25% identity with each other, and are closely related to typical strains. The typical strain J223 is closely related to typical strains, with 99.17% identity with the A449. Genomic differences between atypical and typical strains are strictly related to insertion sequences (ISs) activity. The absence and presence of genes encoding for virulence factors, transcriptional regulators, and non-coding RNAs are the most significant differences between typical and atypical strains that affect their phenotypes. Plasmidome plays an important role in virulence and genome plasticity. Here, we determined that typical strains harbor a larger number of plasmids and virulence-related genes that contribute to its acute virulence. In contrast, atypical strains harbor a single, large plasmid and a smaller number of virulence genes, reflected by their less acute virulence and chronic infection. The relationship between phenotype and subspecies' taxonomy is not evident. Comparative genomic analysis based on completed genomes revealed that the subspecies classification is more of a reflection of the ecological niche occupied by bacteria than their divergences at the genomic level except for their accessory genome.
PubMed: 35056638
DOI: 10.3390/microorganisms10010189 -
Genome May 2023All the 36 known species to date of the genus are mesophilic except the species , which includes both psychrophilic and mesophilic subspecies. For 20 years, more and...
All the 36 known species to date of the genus are mesophilic except the species , which includes both psychrophilic and mesophilic subspecies. For 20 years, more and more mesophilic strains have been discovered. Only subsp. has officially been classified as a mesophilic subspecies. Most mesophiles have been isolated in hot countries. We present, for the first time, the characterization of two new mesophilic isolates from Quebec (Canada). Phenotypic and genomic characterizations were carried out on these strains, isolated from dead fish from a fish farm. Isolates 19-K304 and 19-K308 are clearly mesophiles, virulent to the amoeba , a surrogate host, and close to strain Y577, isolated in India. To our knowledge, this is the first time that mesophilic strains isolated from different countries are so similar. The major difference between the isolates is the presence of plasmid pY47-3, a cryptic plasmid that sometimes presents in mesophilic strains. More importantly, our extensive phylogenetic analysis reveals two well-defined clades of mesophilic strains with psychrophiles associated with one of these clades. This helps to have a better understanding of the evolution of this species and the apparition of psychrophilic subspecies.
Topics: Animals; Aeromonas salmonicida; Phylogeny; Dictyostelium; Canada; Cluster Analysis
PubMed: 36780641
DOI: 10.1139/gen-2022-0086 -
RNA (New York, N.Y.) Sep 2023Unique chemical and physical properties are introduced by inserting selenocysteine (Sec) at specific sites within proteins. Recombinant and facile production of...
Unique chemical and physical properties are introduced by inserting selenocysteine (Sec) at specific sites within proteins. Recombinant and facile production of eukaryotic selenoproteins would benefit from a yeast expression system; however, the selenoprotein biosynthetic pathway was lost in the evolution of the kingdom Fungi as it diverged from its eukaryotic relatives. Based on our previous development of efficient selenoprotein production in bacteria, we designed a novel Sec biosynthesis pathway in using translation components. tRNA was mutated to resemble tRNA to allow recognition by seryl-tRNA synthetase as well as selenocysteine synthase (SelA) and selenophosphate synthetase (SelD). Expression of these Sec pathway components was then combined with metabolic engineering of yeast to enable the production of active methionine sulfate reductase enzyme containing genetically encoded Sec. Our report is the first demonstration that yeast is capable of selenoprotein production by site-specific incorporation of Sec.
Topics: Codon, Terminator; Saccharomyces cerevisiae; Aeromonas salmonicida; Protein Engineering; RNA, Transfer, Cys; Humans; Nucleic Acid Conformation
PubMed: 37279998
DOI: 10.1261/rna.079658.123