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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 -
FEMS Microbiology Letters Aug 2022Worldwide, Aeromonas salmonicida is a major bacterial pathogen of fish in both marine and freshwater environments. Despite psychrophilic growth being common for this...
Worldwide, Aeromonas salmonicida is a major bacterial pathogen of fish in both marine and freshwater environments. Despite psychrophilic growth being common for this species, the number of characterized mesophilic strains is increasing. Thus, this species may serve as a model for the study of intraspecies lifestyle diversity. Although bacteria are preyed upon by protozoan predators, their interaction inside or outside the phagocytic pathway of the predator can provide several advantages to the bacteria. To correlate intraspecies diversity with predation outcome, we studied the fate of psychrophilic and mesophilic strains of A. salmonicida cocultured with the ciliate Tetrahymena pyriformis. A total of three types of outcome were observed: digestion, resistance to phagocytosis, and pathogenicity. The psychrophilic strains are fully digested by the ciliate. In contrast, the mesophilic A. salmonicida subsp. pectinolytica strain is pathogenic to the ciliate. All the other mesophilic strains display mechanisms to resist phagocytosis and/or digestion, which allow them to survive ciliate predation. In some cases, passage through the phagocytic pathway resulted in a few mesophilic A. salmonicida being packaged inside fecal pellets. This study sheds light on the great phenotypic diversity observed in the complex range of mechanisms used by A. salmonicida to confront a predator.
Topics: Aeromonas; Aeromonas salmonicida; Animals; Fish Diseases; Fishes; Tetrahymena pyriformis; Virulence
PubMed: 35883218
DOI: 10.1093/femsle/fnac067 -
Infection and Immunity Sep 1993The virulent fish pathogen Aeromonas salmonicida was rapidly killed in vivo when restricted inside a diffusion chamber implanted intraperitoneally in rainbow trout....
The virulent fish pathogen Aeromonas salmonicida was rapidly killed in vivo when restricted inside a diffusion chamber implanted intraperitoneally in rainbow trout. After a period of regrowth, the survivors had acquired resistance to host-mediated bacteriolysis, phagocytosis, and oxidative killing, properties which were subsequently lost by growth in vitro. Resistance to bacteriolysis and phagocytosis was associated with a newly acquired capsular layer revealed by acidic polysaccharide staining and electron microscopy. This capsular layer shielded the underlying, regular surface array (S-layer) from immunogold labeling with a primary antibody to the S-layer protein. Resistance to oxidative killing was mediated by a mechanism not associated with the presence of the capsular layer. An attenuated vaccine strain of A. salmonicida grown in vivo failed to express the capsular layer. Consequently, the in vivo-grown cells of this attenuated strain remained as sensitive to bacteriolysis, and as avidly adherent to macrophages, as the in vitro-grown cells. The importance of these new virulence determinants and their relation to the known virulence factors of A. salmonicida are discussed.
Topics: Aeromonas; Animals; Bacterial Adhesion; Bacterial Capsules; Diffusion Chambers, Culture; Immunohistochemistry; Macrophages; Microscopy, Electron; Trout; Virulence
PubMed: 8359906
DOI: 10.1128/iai.61.9.3854-3862.1993 -
BMC Microbiology Apr 2012Aeromonas spp. are versatile bacteria that exhibit a wide variety of lifestyles. In an attempt to improve the understanding of human aeromonosis, we investigated whether...
BACKGROUND
Aeromonas spp. are versatile bacteria that exhibit a wide variety of lifestyles. In an attempt to improve the understanding of human aeromonosis, we investigated whether clinical isolates displayed specific characteristics in terms of genetic diversity, population structure and mode of evolution among Aeromonas spp. A collection of 195 Aeromonas isolates from human, animal and environmental sources was therefore genotyped using multilocus sequence analysis (MLSA) based on the dnaK, gltA, gyrB, radA, rpoB, tsf and zipA genes.
RESULTS
The MLSA showed a high level of genetic diversity among the population, and multilocus-based phylogenetic analysis (MLPA) revealed 3 major clades: the A. veronii, A. hydrophila and A. caviae clades, among the eleven clades detected. Lower genetic diversity was observed within the A. caviae clade as well as among clinical isolates compared to environmental isolates. Clonal complexes, each of which included a limited number of strains, mainly corresponded to host-associated subsclusters of strains, i.e., a fish-associated subset within A. salmonicida and 11 human-associated subsets, 9 of which included only disease-associated strains. The population structure was shown to be clonal, with modes of evolution that involved mutations in general and recombination events locally. Recombination was detected in 5 genes in the MLSA scheme and concerned approximately 50% of the STs. Therefore, these recombination events could explain the observed phylogenetic incongruities and low robustness. However, the MLPA globally confirmed the current systematics of the genus Aeromonas.
CONCLUSIONS
Evolution in the genus Aeromonas has resulted in exceptionally high genetic diversity. Emerging from this diversity, subsets of strains appeared to be host adapted and/or "disease specialized" while the A. caviae clade displayed an atypical tempo of evolution among aeromonads. Considering that A. salmonicida has been described as a genetically uniform pathogen that has adapted to fish through evolution from a variable ancestral population, we hypothesize that the population structure of aeromonads described herein suggested an ongoing process of adaptation to specialized niches associated with different degrees of advancement according to clades and clusters.
Topics: Aeromonas; Animals; Cluster Analysis; DNA, Bacterial; Environmental Microbiology; Evolution, Molecular; Fishes; Genetic Variation; Genotype; Gram-Negative Bacterial Infections; Humans; Molecular Sequence Data; Multilocus Sequence Typing; Phylogeny; Sequence Analysis, DNA
PubMed: 22545815
DOI: 10.1186/1471-2180-12-62 -
Journal of Global Antimicrobial... Dec 2023
Topics: Aeromonas caviae; beta-Lactamases; Aeromonas
PubMed: 37918788
DOI: 10.1016/j.jgar.2023.10.020 -
Brazilian Journal of Microbiology :... Mar 2021Aeromonas are bacteria broadly spread in the environment, particularly in aquatic habitats and can induce human infections. Several virulence factors have been described... (Comparative Study)
Comparative Study
Aeromonas are bacteria broadly spread in the environment, particularly in aquatic habitats and can induce human infections. Several virulence factors have been described associated with bacterial pathogenicity, such as the Type VI Secretion System (T6SS). This system translocates effector proteins into target cells through a bacteriophage-like contractile structure encoded by tss genes. Here, a total of 446 Aeromonas genome sequences were screened for T6SS and the proteins subjected to in silico analysis. The T6SS-encoding locus was detected in 243 genomes and its genes are encoded in a cluster containing 13 core and 5 accessory genes, in highly conserved synteny. The amino acid residues identity of T6SS proteins ranges from 78 to 98.8%. In most strains, a pair of tssD and tssI is located upstream the cluster (tssD-2, tssI-2) and another pair was detected distant from the cluster (tssD-1, tssI-1). Significant variability was seen in TssI (VgrG) C-terminal region, which was sorted in four groups based on its sequence length and protein domains. TssI containing ADP-ribosyltransferase domain are associated exclusively with TssI-1, while genes coding proteins carrying DUF4123 (a conserved domain of unknown function) were observed downstream tssI-1 or tssI-2 and escort of possible effector proteins. Genes coding proteins containing DUF1910 and DUF1911 domains were located only downstream tssI-2 and might represent a pair of toxin/immunity proteins. Nearly all strains display downstream tssI-3, that codes for a lysozyme family domain protein. These data reveal that Aeromonas T6SS cluster synteny is conserved and the low identity observed for some genes might be due to species heterogeneity or its niche/functionality.
Topics: Aeromonas; Bacterial Proteins; Computer Simulation; Genome, Bacterial; Multigene Family; Sequence Analysis, Protein; Type VI Secretion Systems; Virulence Factors
PubMed: 33410103
DOI: 10.1007/s42770-020-00405-y -
Journal of Global Antimicrobial... Mar 2018The 'One Health' concept recognises that the health of humans, animals and the environment are interconnected. Therefore, knowledge on the behaviour of micro-organisms...
OBJECTIVES
The 'One Health' concept recognises that the health of humans, animals and the environment are interconnected. Therefore, knowledge on the behaviour of micro-organisms from the most diverse environmental niches is important to prevent the emergence and dissemination of antimicrobial resistance. Wild animals are known to carry antimicrobial-resistant micro-organisms with potential public health impact. However, no data are available on the behaviour of sessile bacteria from wild animals, although antimicrobial resistance is amplified in biofilms. This study characterised the ciprofloxacin susceptibility and the adhesion and biofilm formation abilities of 14 distinct Aeromonas spp. (8 Aeromonas salmonicida, 3 Aeromonas eucrenophila, 2 Aeromonas bestiarum and 1 Aeromonas veronii) isolated from wild animals and already characterised as resistant to β-lactam antibiotics.
METHODS
The ciprofloxacin MIC was determined according to CLSI guidelines. A biofilm formation assay was performed by a modified microtitre plate method. Bacterial surface hydrophobicity was assessed by sessile drop contact angle measurement.
RESULTS
All Aeromonas spp. strains were resistant to ciprofloxacin (MICs of 6-60μg/mL) and had hydrophilic surfaces (range 2-37mJ/m). These strains were able to adhere and form biofilms with distinct magnitudes. Biofilm exposure to 10×MIC of ciprofloxacin only caused low to moderate biofilm removal.
CONCLUSIONS
This study shows that the strains tested are of potential public health concern and emphasises that wild animals are potential reservoirs of multidrug-resistant strains. In fact, Aeromonas spp. are consistently considered opportunistic pathogens. Moreover, bacterial ability to form biofilms increases antimicrobial resistance and the propensity to cause persistent infections.
Topics: Aeromonas; Animals; Animals, Wild; Anti-Bacterial Agents; Biofilms; Ciprofloxacin; Deer; Drug Resistance, Bacterial; Microbial Sensitivity Tests; Snakes; Strigiformes
PubMed: 28951073
DOI: 10.1016/j.jgar.2017.09.010 -
Microbiological Sciences Jun 1986Comparisons between the ribonucleotide sequences of 5S rRNAs of the Gram-negative eubacteria indicate that several families, namely Enterobacteriaceae, Vibrionaceae and... (Review)
Review
Comparisons between the ribonucleotide sequences of 5S rRNAs of the Gram-negative eubacteria indicate that several families, namely Enterobacteriaceae, Vibrionaceae and Aeromonadaceae possess remarkably similar evolutionary histories. A study of the phylogenetic relationships among these groups, through cluster analysis and construction of evolutionary trees, suggests the existence of dissimilar rates of evolution along the several lineages. These dissimilarities are most evident in comparisons between the phylogenetic depths of the Enterobacteriaceae and Vibrionaceae. Detection of disparate rates of evolution, as well as their influence on the interpretation of the natural taxonomy of this group of bacteria, is discussed.
Topics: Aeromonas; Biological Evolution; Enterobacteriaceae; Phylogeny; RNA, Bacterial; RNA, Ribosomal, 5S; Vibrionaceae
PubMed: 2484672
DOI: No ID Found -
Journal of Fish Diseases Jan 2022Aeromonas salmonicida subspecies salmonicida, a fish pathogen, expresses various virulence factors such as an A-layer, lipases and proteases during the infection...
Aeromonas salmonicida subspecies salmonicida, a fish pathogen, expresses various virulence factors such as an A-layer, lipases and proteases during the infection process. Not all strains of this bacterium express the same virulence factors. It is important to be able to evaluate which factors are present when characterizing strains. The A-layer and secreted lipases and proteases are usually detected by agar-based tests that require long incubation (24 h and more) and may provide ambiguous results. In the present study, protocols have been optimized to determine the presence of these virulence factors using liquid tests. For A-layer detection, the optimized method stains the positive bacteria with Coomassie Brilliant Blue. The lipases are detected by a colorimetric biochemical reaction triggered by the degradation of p-nitrophenyl dodecanoate into a yellow product detectable by spectrophotometry, if the result is positive. Both of these tests show results in less than an hour. Finally, the protease activity is measured by clarification of a medium containing milk during an overnight bacterial growth. These new protocols provide opportunities for quicker characterization of A. salmonicida subsp. salmonicida strains and, particularly, provide more precise results.
Topics: Aeromonas; Aeromonas salmonicida; Animals; Fish Diseases; Virulence; Virulence Factors
PubMed: 34748248
DOI: 10.1111/jfd.13547 -
Journal of Fish Diseases May 2023Aeromonas salmonicida has long been known as psychrophiles since it is mainly isolated from cold water fish, and recent reports have revealed the existence of mesophilic...
Aeromonas salmonicida has long been known as psychrophiles since it is mainly isolated from cold water fish, and recent reports have revealed the existence of mesophilic strains isolated from warm sources. However, the genetic differences between mesophilic and psychrophilic strains remain unclear due to few complete genomes of mesophilic strain are available. In this study, six A. salmonicida (2 mesophilic and 4 psychrophilic) were genome-sequenced, and comparative analyses of 25 A. salmonicida complete genomes were conducted. The ANI values and phylogenetic analysis revealed that 25 strains formed three independent clades, which were referred as typical psychrophilic, atypical psychrophilic and mesophilic groups. Comparative genomic analysis showed that two chromosomal gene clusters, related to lateral flagella and outer membrane proteins (A-layer and T2SS proteins), and insertion sequences (ISAs4, ISAs7 and ISAs29) were unique to the psychrophilic groups, while the complete MSH type IV pili were unique to the mesophilic group, all of which may be considered as lifestyle-related factors. The results of this study not only provide new insights into the classification, lifestyle adaption and pathogenic mechanism of different strains of A. salmonicida, but also contributes to the prevention and control of disease caused by psychrophilic and mesophilic A. salmonicida.
Topics: Animals; Aeromonas salmonicida; Temperature; Phylogeny; Fish Diseases; Genomics; Aeromonas
PubMed: 36861816
DOI: 10.1111/jfd.13767