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Journal of Bacteriology Jan 2002Swarming motility, a flagellum-dependent behavior that allows bacteria to move over solid surfaces, has been implicated in biofilm formation and bacterial virulence. In...
Swarming motility, a flagellum-dependent behavior that allows bacteria to move over solid surfaces, has been implicated in biofilm formation and bacterial virulence. In this study, light and electron microscopic analyses and genetic and functional investigations have shown that at least 50% of Aeromonas isolates from the species most commonly associated with diarrheal illness produce lateral flagella which mediate swarming motility. Aeromonas lateral flagella were optimally produced when bacteria were grown on solid medium for approximately 8 h. Transmission and thin-section electron microscopy confirmed that these flagella do not possess a sheath structure. Southern analysis of Aeromonas reference strains and strains of mesophilic species (n = 84, varied sources and geographic regions) with a probe designed to detect lateral flagellin genes (lafA1 and lafA2) showed there was no marked species association of laf distribution. Approximately 50% of these strains hybridized strongly with the probe, in good agreement with the expression studies. We established a reproducible swarming assay (0.5% Eiken agar in Difco broth, 30 degrees C) for Aeromonas spp. The laf-positive strains exhibited vigorous swarming motility, whereas laf-negative strains grew but showed no movement from the inoculation site. Light and scanning electron microscopic investigations revealed that lateral flagella formed bacterium-bacterium linkages on the agar surface. Strains of an Aeromonas caviae isolate in which lateral flagellum expression was abrogated by specific mutations in flagellar genes did not swarm, proving conclusively that lateral flagella are required for the surface movement. Whether lateral flagella and swarming motility contribute to Aeromonas intestinal colonization and virulence remains to be determined.
Topics: Aeromonas; Agar; Flagella; Flagellin; Genes, Bacterial; Microscopy, Electron; Mutagenesis
PubMed: 11751834
DOI: 10.1128/JB.184.2.547-555.2002 -
Applied and Environmental Microbiology Nov 2012Vertebrate metamorphosis is often marked by dramatic morphological and physiological changes of the alimentary tract, along with major shifts in diet following...
Vertebrate metamorphosis is often marked by dramatic morphological and physiological changes of the alimentary tract, along with major shifts in diet following development from larva to adult. Little is known about how these developmental changes impact the gut microbiome of the host organism. The metamorphosis of the sea lamprey (Petromyzon marinus) from a sedentary filter-feeding larva to a free-swimming sanguivorous parasite is characterized by major physiological and morphological changes to all organ systems. The transformation of the alimentary canal includes closure of the larval esophagus and the physical isolation of the pharynx from the remainder of the gut, which results in a nonfeeding period that can last up to 8 months. To determine how the gut microbiome is affected by metamorphosis, the microbial communities of feeding and nonfeeding larval and parasitic sea lamprey were surveyed using both culture-dependent and -independent methods. Our results show that the gut of the filter-feeding larva contains a greater diversity of bacteria than that of the blood-feeding parasite, with the parasite gut being dominated by Aeromonas and, to a lesser extent, Citrobacter and Shewanella. Phylogenetic analysis of the culturable Aeromonas from both the larval and parasitic gut revealed that at least five distinct species were represented. Phenotypic characterization of these isolates revealed that over half were capable of sheep red blood cell hemolysis, but all were capable of trout red blood cell hemolysis. This suggests that the enrichment of Aeromonas that accompanies metamorphosis is likely related to the sanguivorous lifestyle of the parasitic sea lamprey.
Topics: Aeromonas; Animals; Biodiversity; DNA Gyrase; Gastrointestinal Tract; Metagenome; Metamorphosis, Biological; Microbial Consortia; Molecular Sequence Data; Petromyzon; Phylogeny; RNA, Ribosomal, 16S; Sequence Analysis, DNA
PubMed: 22923392
DOI: 10.1128/AEM.01640-12 -
Toxins Jun 2020exotoxin A (AE) is a bacterial virulence factor recently discovered in a clinical case of necrotising fasciitis caused by the flesh-eating . Here, database mining shows...
exotoxin A (AE) is a bacterial virulence factor recently discovered in a clinical case of necrotising fasciitis caused by the flesh-eating . Here, database mining shows that AE is present in the genome of several emerging pathogenic species. The X-ray crystal structure of AE was solved at 2.3 Å and presents all the hallmarks common to diphthamide-specific mono-ADP-ribosylating toxins, suggesting AE is a fourth member of this family alongside the diphtheria toxin, exotoxin A and cholix. Structural homology indicates AE may use a similar mechanism of cytotoxicity that targets eukaryotic elongation factor 2 and thus inhibition of protein synthesis. The structure of AE also highlights unique features including a metal binding site, and a negatively charged cleft that could play a role in interdomain interactions and may affect toxicity. This study raises new opportunities to engineer alternative toxin-based molecules with pharmaceutical potential.
Topics: ADP Ribose Transferases; Aeromonas; Crystallization; Crystallography, X-Ray; Enterotoxins; Protein Conformation; Structure-Activity Relationship; Virulence Factors
PubMed: 32549399
DOI: 10.3390/toxins12060397 -
Journal of Applied Microbiology 2003The aim of the study was to type 52 Aeromonas spp. isolates from chicken carcasses, children with diarrhoea and a hospital environment in Libya, and to determine the...
AIMS
The aim of the study was to type 52 Aeromonas spp. isolates from chicken carcasses, children with diarrhoea and a hospital environment in Libya, and to determine the distribution of putative virulence genes amongst them.
METHODS AND RESULTS
Macrorestriction analysis using pulsed-field gel electrophoresis (PFGE) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of 16S rRNA and aroA genes were used to type the isolates. Whereas 30 of 32 chicken isolates were identified as Aeromonas veronii, eight of 12 environmental isolates were Aer. caviae. Three species were identified amongst the eight isolates from children. Aeromonas veronii and Aer. caviae isolates could be divided into eight and five PFGE types, respectively. All species could be further subtyped into one of 21 aroA PCR-RFLP groups. Aerolysin-like haemolysin or enterotoxin gene sequences were detected in all the isolates. Overall carriage rates for hlyA and alt were 77 and 75%, respectively.
CONCLUSIONS
Seven of eight isolates from children were of different subtypes, indicating a lack of any common source of acquisition. Isolates of common molecular type did not share identical distributions of putative virulence genes.
SIGNIFICANCE AND IMPACT OF THE STUDY
This study demonstrates the effectiveness of using molecular typing to identify and study genetic variation amongst Aeromonas isolates.
Topics: Aeromonas; Animals; Bacterial Typing Techniques; Chickens; Child; Diarrhea; Electrophoresis, Gel, Pulsed-Field; Endopeptidases; Enterotoxins; Genes, Bacterial; Hemolysis; Humans; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; RNA, Bacterial; RNA, Ribosomal, 16S; Virulence
PubMed: 14633028
DOI: 10.1046/j.1365-2672.2003.02092.x -
Journal of Food Protection Mar 2002Aeromonas species have been recognized as potential or emerging foodborne pathogens for more than 20 years. Aeromonads are estuarine bacteria and are ubiquitous in fresh... (Review)
Review
Aeromonas species have been recognized as potential or emerging foodborne pathogens for more than 20 years. Aeromonads are estuarine bacteria and are ubiquitous in fresh water, fish and shellfish, meats, and fresh vegetables. Actual sourced foodborne outbreaks are few, but epidemiological evidence suggests that the bacterium can cause self-limiting diarrhea, with children being the most susceptible population. Most aeromonads are psychrotrophic and can grow in foods during cold storage. Aeromonads are not resistant to food processing regimes and are readily killed by heat treatment. A host of virulence factors are present, but the exact role of each in human disease has not been fully elucidated.
Topics: Aeromonas; Animals; Disease Outbreaks; Food Contamination; Food Microbiology; Humans; Hydrogen-Ion Concentration; Seafood; Virulence
PubMed: 11899061
DOI: 10.4315/0362-028x-65.3.575 -
Journal of Applied Microbiology 2002To evaluate the relationship between the genomospecies, phenotypic profile and pathogenicity for carp of 37 motile Aeromonas strains.
AIMS
To evaluate the relationship between the genomospecies, phenotypic profile and pathogenicity for carp of 37 motile Aeromonas strains.
METHODS AND RESULTS
Aeromonas strains were identified to genomospecies level by the 16S rDNA restriction fragment length polymorphism (RFLP) method and characterized phenotypically by the API 20E and API Zym systems and by conventional tube or plate methods. 16S rDNA RFLP analysis showed that the strains belonged to five species, Aeromonas bestiarum (5), Aerom. salmonicida (13), Aerom. veronii (11), Aerom. sobria (6) and Aerom. encheleia (2). Most strains of Aerom. bestiarum (80%) and Aerom. salmonicida (85%) could be separated by growth at 4 and 42 degrees C, autoagglutination after boiling, reaction for lipase (C14) and naphthol-AS-BI-phosphohydrolase. All strains of Aerom. veronii corresponded to Aerom. veronii biotype sobria and could be separated from Aerom. sobria by citrate utilization, growth at 37 and 42 degrees C, amygdalin and cellobiose fermentation. All strains of Aerom. bestiarum and most strains of Aerom. salmonicida (76.9%) and Aerom. veronii (63.6%) were pathogenic for carp.
CONCLUSIONS
The biochemical identification of carp Aeromonas strains is not entirely clear. Some association between Aeromonas species, phenotypic profile and specific disease signs was observed.
SIGNIFICANCE AND IMPACT OF THE STUDY
The results will be useful for ichthyopathology laboratories in the diagnosis of motile aeromonad septicaemia in carp.
Topics: Aeromonas; Animals; Carps; Fish Diseases; Genome, Bacterial; Gram-Negative Bacterial Infections; Hemorrhagic Septicemia; Phenotype; Ribotyping; Species Specificity; Virulence
PubMed: 12452960
DOI: 10.1046/j.1365-2672.2002.01784.x -
Infection and Immunity Feb 1982To evaluate the enteropathogenicity of Aeromonas hydrophila and Plesiomonas shigelloides, the rate of isolation of these organisms was compared among individuals with...
To evaluate the enteropathogenicity of Aeromonas hydrophila and Plesiomonas shigelloides, the rate of isolation of these organisms was compared among individuals with and without diarrhea in Thailand. In two groups of American travelers, A. hydrophila, but not P. shigelloides, was associated with episodes of travelers diarrhea more often than when individuals did not have diarrhea (P less than 0.025). Among three populations of Thais, A. hydrophila and P. shigelloides were isolated with similar frequencies from individuals with and without diarrhea. The biochemical characteristics, production of cytotoxin, and ability to distend suckling mouse intestine were similar among A. hydrophila isolates from individuals with and without diarrhea. However, cytotoxic A. hydrophila strains distended rabbit and suckling mouse intestine and produced destructive lesions in intestinal mucosa of both species of animal. P. shigelloides strains produced neither cytotoxin nor distended intestine. Oral administration of whole cultures (10(9)) of cytotoxic A. hydrophila or P. shigelloides failed to cause diarrhea in rhesus monkeys. Volunteer studies or intestinal biopsies of patients with diarrhea may be required to establish whether A. hydrophila is a gastrointestinal pathogen in humans.
Topics: Adolescent; Adult; Aeromonas; Child; Child, Preschool; Diarrhea; Enterotoxins; Humans; Infant; Infant, Newborn; Thailand; United States; Vibrionaceae
PubMed: 7056580
DOI: 10.1128/iai.35.2.666-673.1982 -
Virulence Dec 2023The emergence of antibiotic-resistant strains in clinical settings has presented an escalating burden on human and public health. The dissemination of antibiotic...
The emergence of antibiotic-resistant strains in clinical settings has presented an escalating burden on human and public health. The dissemination of antibiotic resistance in is predominantly facilitated by chromosome-borne accessory genetic elements, although the existing literature on this subject remains limited. Hence, the primary objective of this study is to comprehensively investigate the genomic characteristics of chromosome-borne accessory genetic elements in . Moreover, the study aims to uncover novel genetic environments associated with antibiotic resistance on these elements. were screened from nonduplicated strains collected from two tertiary hospitals in China. Complete sequencing and population genetics analysis were performed. BLAST analysis was employed to identify related elements. All newly identified elements were subjected to detailed sequence annotation, dissection, and comparison. We identified and newly designated 19 chromosomal elements, including 18 integrative and mobilizable elements (IMEs) that could be classified into four categories: Tn-related, Tn-related, Tn-related, and Tn-related IMEs. Each class exhibited a distinct pattern in the types of resistance genes carried by the IMEs. Several novel antibiotic resistance genetic environments were uncovered in these elements. Notably, we report the first identification of the gene and gene in clinical genome, the first presence of a (E)-(E) resistance gene environment within the backbone region in IMEs, and a new resistance gene environment. The implications of these findings are substantial, as they provide new insights into the evolution, structure, and dissemination of chromosomal-borne accessory elements.
Topics: Humans; Aeromonas; Drug Resistance, Microbial; Anti-Bacterial Agents; Chromosomes; China
PubMed: 37848422
DOI: 10.1080/21505594.2023.2271688 -
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 -
Revista Da Sociedade Brasileira de... 2013The number of reports of intestinal infections caused by Aeromonas spp. has increased significantly in recent years. In most clinical laboratories, identification of...
INTRODUCTION
The number of reports of intestinal infections caused by Aeromonas spp. has increased significantly in recent years. In most clinical laboratories, identification of these bacteria is carried out by general phenotypic tests that sometimes do not accurately differentiate Aeromonas and Vibrio.
METHODS
A duplex-polymerase chain reaction (PCR) was developed directed to 2 targets identifying Aeromonas spp. pathogenic to humans.
RESULTS
The duplex-PCR results were reproducible and specific for Aeromonas spp. pathogenic to humans.
CONCLUSIONS
This method will allow differentiation between Vibrio and Aeromonas spp. in patients with in cholera-like symptoms and can also be used in water quality monitoring.
Topics: Aeromonas; Bacterial Typing Techniques; Diarrhea; Gram-Negative Bacterial Infections; Humans; Polymerase Chain Reaction; Reproducibility of Results; Vibrio
PubMed: 23681432
DOI: 10.1590/0037-8682-1344-2013