-
International Journal of Molecular... Dec 2019is one of the main pathogens causing freshwater fish sepsis and ulcer syndrome. This bacterium has caused serious economic losses in the aquaculture industry worldwide,...
is one of the main pathogens causing freshwater fish sepsis and ulcer syndrome. This bacterium has caused serious economic losses in the aquaculture industry worldwide, and it has become an important zoonotic and aquatic agent. However, little is known about the molecular mechanism of pathogenesis of . In this study, we first constructed an unmarked mutant strain (Δ) by generating an in-frame deletion of the gene, which encodes a periplasmic binding protein, to investigate its role in TH0426. Our results showed that the motility and biofilm formation ability of Δ were similar to those of the wild-type strain. However, the adhesion and invasion ability in (EPC) cells were significantly enhanced (2.0-fold). Furthermore, the median lethal dose (LD) of Δ was 7.6-fold higher than that of the wild-type strain, which illustrates that the virulence of the mutant was significantly enhanced. This finding is also supported by the cytotoxicity test results, which showed that the toxicity of Δ to EPC cells was enhanced 1.3-fold relative to the wild type. Conversely, tolerance test results showed that oxidative stress resistance of Δ decreased 5.9-fold compared to with the wild-type strain. The results suggest that may negatively regulate the virulence of TH0426 through the regulation of resistance to oxidative stress. These insights will help to further elucidate the function of and understand the pathogenesis of
Topics: Aeromonas veronii; Animals; Bacterial Proteins; Carps; Cell Line, Tumor; Cell Proliferation; Oxidative Stress; Virulence; Zebrafish
PubMed: 31877791
DOI: 10.3390/ijms21010098 -
Applied and Environmental Microbiology Mar 2021is included in the Dutch Drinking Water Decree as an indicator for elevated microbial regrowth in non-chlorinated drinking water distribution systems (DWDS). The...
is included in the Dutch Drinking Water Decree as an indicator for elevated microbial regrowth in non-chlorinated drinking water distribution systems (DWDS). The temporal and spatial diversity of species in ten DWDS and their planktonic growth characteristics for different carbon sources was investigated. Genotyping of the B gene of isolates showed a non-systematic temporal and spatial variable prevalence of seven different species in these DWDS and no correlation with AOC-P17/NOX and concentrations. Pure cultures of these seven species showed a high affinity to low concentrations (μg/L) of individual amino acids and fatty acids, compounds associated with biomass. Growth occurred at 0.5 μg-C/L of an amino acid mixture. Growth of a mixed community of , , and in drinking water occurred in pasteurized samples, however, no growth and decay occurred in competition with the autochthonous bacteria (non-pasteurized samples). This community also failed to grow in non-pasteurized distribution samples from a location with clear increase in planktonic concentrations in the transported drinking water. For competitive planktonic growth of an amino acid concentration of ≥5 μg-C/L is required. AOC-P17/NOX concentrations showed that such concentrations are not expected in Dutch drinking water. Therefore, we suspect that competitive planktonic growth is not the major cause of the observed non-compliance with the standard in non-chlorinated DWSD. The occurrence of the bacterial genus in non-chlorinated drinking water in the Netherlands is regarded as an indication for elevated microbial regrowth in the distribution system. Identification of the prevalent species in ten distribution systems by genotyping yielded seven different species, with , and as the most dominant ones. Planktonic growth experiments of pure cultures confirmed former published affinity of for certain biomass compounds (amino and fatty acids). In competition with the autochthonous microflora, however, planktonic growth was not observed, only after addition of a threshold amino acid concentration of 5 μg-C/L. Based on our results and further observations we deduced that planktonic growth of in the DWDS is not very likely. Benthic growth in loose deposits and planktonic release is a more plausible explanation for the observed planktonic increase of .
PubMed: 33310721
DOI: 10.1128/AEM.02867-20 -
Animals : An Open Access Journal From... Jan 2024The ubiquitous Gram-negative bacterial pathogen () can easily cause inflammatory reactions in aquatic organisms, resulting in high mortality and huge economic losses....
The ubiquitous Gram-negative bacterial pathogen () can easily cause inflammatory reactions in aquatic organisms, resulting in high mortality and huge economic losses. MicroRNAs (miRNAs) participate in immune regulation and have certain conserved properties. MiRNAs are involved in the immune responses of a variety of teleost fish infected with bacteria, whereas there is no related report in silver carp (). Therefore, we identified the expression profiles of miRNA in silver carp stimulated by and LPS. Among them, the quantity of differentially expressed miRNAs (DEmiRNAs) obtained in the silver carp challenge group was 73 () and 90 (LPS). The GO enrichment and analysis of KEGG pathways have shown that the predicted target genes are mainly associated with lipid metabolism and the immune response in silver carp. This indicates the possibility that miRNAs play a role in regulating immune-related pathways. In addition, a total of eight DEmiRNAs validated the accuracy of the sequencing result via quantitative real-time PCR (qRT-PCR). Finally, we selected the silver carp head kidney macrophage cells (HKCs) as model cells and proved that miR-30b-5p can regulate the inflammatory response in silver carp HKCs. This study lays the foundation for exploring miRNA regulation in silver carp during pathogenic bacterial infection. In addition, it provides a reference for the future development of non-coding RNA antibacterial drugs.
PubMed: 38254454
DOI: 10.3390/ani14020285 -
Applied and Environmental Microbiology Feb 2002Sparse information is available on the virulence factors of Aeromonas strains isolated from diseased fish, from the environment, and from humans. In the present study,...
Sparse information is available on the virulence factors of Aeromonas strains isolated from diseased fish, from the environment, and from humans. In the present study, 52 Aeromonas isolates obtained from epizootic ulcerative syndrome (EUS) lesions in fish, from the aquatic environment, and from children with diarrhea in Bangladesh were identified by biochemical phenotyping (i.e., PhenePlate [PhP] typing) and DNA fingerprinting and then characterized with respect to certain putative virulence factors. The isolates from the fish exhibiting EUS symptoms were identified to be Aeromonas veronii biovar sobria by fatty acid methyl ester analysis and amplified fragment length polymorphism fingerprinting. Biochemical phenotyping revealed that all EUS-associated isolates belonged to a unique phenotype which was not identified among more than 1,600 environmental and diarrheal isolates in a previously collected database of PhP types of Bangladeshi Aeromonas isolates. The 52 Aeromonas isolates were investigated for the production of hemolysin and cytotoxin; for hemagglutination with erythrocytes from fish, human, and rabbit sources; for the presence of a cytolytic enterotoxin gene; and for adhesion to and invasion into fish cell lines. All of the EUS isolates produced all of the virulence factors investigated, as did also some of the environmental isolates, but the isolates from EUS were unique in their ability to agglutinate fish erythrocytes. Our results suggest that a clonal group of A. veronii biovar sobria is associated with, and may be a causative agent of, EUS in fish in Bangladesh.
Topics: Aeromonas; Animals; Bacterial Adhesion; Bacterial Toxins; Bacterial Typing Techniques; Bangladesh; Catfishes; Diarrhea; Fish Diseases; Fishes; Gram-Negative Bacterial Infections; Hemagglutination Tests; Humans; Polymerase Chain Reaction; Rabbits; Virulence
PubMed: 11823203
DOI: 10.1128/AEM.68.2.650-655.2002 -
Antimicrobial Resistance and Infection... Feb 2021The study aimed to elucidate the species taxonomy, clinical manifestations, virulence gene profiles and antimicrobial susceptibilities of Aeromonas strains isolated from...
BACKGROUND
The study aimed to elucidate the species taxonomy, clinical manifestations, virulence gene profiles and antimicrobial susceptibilities of Aeromonas strains isolated from life-threatening bacteremia in southeastern China.
METHODS
Clinical samples of Aeromonas causing bacteremia were isolated from a teaching hospital in Wenzhou from 2013 to 2018 and a retrospective cohort study was performed. Aeromonas strains were identified at species level by housekeeping gene gyrB. Virulence and drug resistance-associated genes were screened by polymerase chain reaction (PCR) and antimicrobial susceptibility testing (AST) was performed by the VITEK 2 Compact system.
RESULTS
A total of 58 Aeromonas isolated from patients with bacteremia were collected during 6 years (2013-2018). 58 isolates were identified to five different species, where Aeromonas dhakensis appeared to be the predominant species (26/58), followed by Aeromonas veronii (13/58), Aeromonas caviae (10/58), Aeromonas hydrophila (7/58) and Aeromonas jandaei (2/58). 16 of 58 patients had poor prognosis. Poor prognosis was significantly associated with liver cirrhosis and inappropriate empirical antimicrobials therapy. The progression of bacteremia caused by Aeromonas was extremely fast, especially in A. dhakensis infections. Virulence genes aer, lip, hlyA, alt, ast, and act, were detected at ratios of 24.1% (14/58), 62.1% (36/58), 65.5% (38/58), 58.6% (34/58), 15.5% (9/58) and 65.5% (38/58), respectively. Antimicrobial susceptibility testing exhibited that 9 out of 58 isolates were identified as multi-drug resistant (MDR) organism. The bla gene was identified in all 9 MDR isolates. bla, bla, bla, bla, bla and aac(6')-Ib-cr were detected in 4 isolates, 2 isolates, 1 isolate, 3 isolates, 8 isolates, and 3 isolates, respectively. The majority of Aeromonas strains maintained susceptible to 3rd generation cephalosporins, aminoglycosides, fluoroquinolones and furantoin.
CONCLUSIONS
The prevalence and dangerousness of Aeromonas infections, especially A. dhakensis, are underestimated in clinic. Continuous monitoring is essential to keep track of MDR Aeromonas due to the increasing prevalence recently and a more effective measure is required to control the spread of resistance determinants.
Topics: Adult; Aeromonas; Aged; Anti-Bacterial Agents; Bacteremia; China; Female; Gram-Negative Bacterial Infections; Hospitals, Teaching; Humans; Male; Microbial Sensitivity Tests; Middle Aged; Phylogeny; Retrospective Studies; Virulence; Virulence Factors
PubMed: 33640019
DOI: 10.1186/s13756-021-00911-0 -
Journal of Applied Microbiology 2002To evaluate the public health significance of representative strains of two Aeromonas spp., mainly from freshwater fish, on the basis of production of...
AIMS
To evaluate the public health significance of representative strains of two Aeromonas spp., mainly from freshwater fish, on the basis of production of virulence-associated factors and presence of the haemolytic genes aerA and hlyA.
METHODS AND RESULTS
Eleven strains of Aer. hydrophila, three strains of Aer. veronii biovar sobria (all from freshwater fish) and one strain of Aer. hydrophila from human diarrhoea were tested for potential virulence traits and for the presence of the haemolytic genes aerA and hlyA. Ten Aer. hydrophila isolates were aerA(+)hlyA(+) and two aerA(+)hlyA(-). Aeromonas veronii biovar sobria isolates were aerA(-)hlyA(-). Strains from the three genotypes showed enterotoxic activity in the suckling mouse assay. At 28 degrees C, four Aer. hydrophila fish strains could be considered as potentially virulent (possessing at least two of these characteristics: haemolytic, cytotoxic and enterotoxic). One Aer. veronii biovar sobria strain and the clinical isolate were cytotoxic on Vero cells. When grown at 4 degrees C, these six isolates fulfilled virulence criterion, but at 37 degrees C, only one fish strain, an Aer. hydrophila, did.
CONCLUSIONS
The potential health risk derived from the presence of Aer. hydrophila and Aer. veronii biovar sobria in ice-stored freshwater fish should not be underestimated.
SIGNIFICANCE AND IMPACT OF THE STUDY
Expression of virulence factors is affected by temperature incubation and not always related to the presence of haemolytic genes.
Topics: Aeromonas; Aeromonas hydrophila; Animals; Animals, Suckling; Bacterial Proteins; Bacterial Toxins; Chlorocebus aethiops; Diarrhea; Esocidae; Fish Diseases; Fresh Water; Gram-Negative Bacterial Infections; Hemolysin Proteins; Humans; Mice; Oncorhynchus mykiss; Pore Forming Cytotoxic Proteins; Temperature; Toxicity Tests; Vero Cells; Virulence
PubMed: 12174039
DOI: 10.1046/j.1365-2672.2002.01705.x -
Antibiotics (Basel, Switzerland) Feb 2024spp. are environmental bacteria able to infect animals and humans. Here, we aim to evaluate the role of biofilms in persistence in freshwater. were isolated from...
spp. are environmental bacteria able to infect animals and humans. Here, we aim to evaluate the role of biofilms in persistence in freshwater. were isolated from water and biofilm samples and identified by Vitek-MS and sequencing. Antibiotic susceptibility profiles were determined according to EUCAST, and a crystal violet assay was used to assess biofilm assembly. MTT and the enumeration of colony-forming units were used to evaluate biofilm and planktonic susceptibility to chlorination, respectively. Identification at the species level was challenging, suggesting the need to improve the used methodologies. Five different species (, , , and ) were identified from water, and one species was identified from biofilms (). and presented resistance to different antibiotics, whith the highest resistance rate observed for (multiple antibiotic resistance index of 0.25). Of the 21 isolates, 11 were biofilm producers, and 10 of them were strong biofilm producers (SBPs). The SBPs presented increased tolerance to chlorine disinfection when compared with their planktonic counterparts. In order to elucidate the mechanisms underlying biofilm tolerance to chlorine and support the importance of preventing biofilm assembly in water reservoirs, further research is required.
PubMed: 38391552
DOI: 10.3390/antibiotics13020166 -
Animals : An Open Access Journal From... Apr 2020is an important pathogen causing freshwater fish sepsis and ulcer syndrome. An increasing number of cases have demonstrated its significance as an aquatic zoonotic...
is an important pathogen causing freshwater fish sepsis and ulcer syndrome. An increasing number of cases have demonstrated its significance as an aquatic zoonotic agent. The purpose of this study was to ensure the safety of freshwater products by evaluating the infection status of edible freshwater fish. In this experiment, we isolated from several species of apparently healthy freshwater fish, including , , , and . was identified through bacterial staining, culture characteristics, and 16S rDNA gene sequence. In addition, polymerase chain reaction (PCR) was used to investigate the distribution of seven major virulence genes, including aerolysin (: 88.51%), cytotoxic enterotoxin (: 71.26%), serine proteinase (: 54.02%), adhesin (: 40.23%), phospholipase (: 45.98%), nuclease (: 51.72%), and quorum sensing-controlled virulence factor (: 59.77%). In total, 496 strains of were isolated, including 87 strains of . The isolates of were Gram-negative, rod-shaped bacteria, and the colonies are yellow on Rimler-Shotts (RS) medium and showed greater than 99% homology with ATCC35624 according to analyses of the 16S rDNA sequence. Nearly 50% of the isolates carried at least four or more virulence genes, 25% of the isolates carried at least five types of virulence genes, and 59.77% isolates carried the gene, and the isolates carrying more virulence genes were found to be more virulent. These results are of great significance for further improving the food safety assessment of freshwater aquatic products.
PubMed: 32252334
DOI: 10.3390/ani10040608 -
Antibiotics (Basel, Switzerland) Aug 2022A patient with oral squamous cell carcinoma (OSCC) underwent complex surgical tumor therapy, including the reconstruction of soft tissues using a radial forearm flap....
A patient with oral squamous cell carcinoma (OSCC) underwent complex surgical tumor therapy, including the reconstruction of soft tissues using a radial forearm flap. Due to venous congestion that could only partly be resolved by revision surgery, leech therapy was started on the second postoperative day. The patient developed pneumonia and sepsis and died as a result of septic shock, despite having received targeted broad-spectrum antibiotic therapy since day 5. spp. were cultured from both the patient's specimens and unused leeches. Biochemical identification and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) yielded inconsistent identification results. Finally, microbiological identification of spp. was performed via 16S rDNA sequencing and use of the basic local alignment search tool (BLAST), and strains from both the patient and the leeches were identified as . spp. strains derived from the patient and leeches and independent laboratory strains were submitted to randomly amplified polymorphic DNA (RAPD) subtyping. RAPD of strains from both sources revealed an identical pattern, strongly suggesting the transmission of from the leeches to the patient. Physicians should be aware of the potential for severe lethal infections as a fatal side-effect of leech therapy in critically ill patients, which should be addressed using antibiotic prophylaxis.
PubMed: 36139958
DOI: 10.3390/antibiotics11091180 -
Frontiers in Microbiology 2022The aquatic environment is an important medium for the accumulation and dissemination of antibiotic-resistant bacteria as it is often closely related to human...
The aquatic environment is an important medium for the accumulation and dissemination of antibiotic-resistant bacteria as it is often closely related to human activities. Previous studies paid little attention to the prevalence and mechanism of polymyxin-resistant bacteria in the aquatic environment. As a Gram-negative opportunistic pathogen widely distributed in aquatic ecosystems, the antibiotic-resistant profile of spp. deserves much attention. In this study, we identified 61 spp. isolates from water samples in the section of the Yangtze River. The total polymyxin B (PMB) resistance rate of these strains was 49.18% (30/61), showing a high level of polymyxin resistance in spp. The MIC and MIC for PMB exhibited a significant discrepancy among different species ( < 0.001). The MIC and MIC for PMB in the were 128 mg/L and above 128 mg/L while in and , the MIC and MIC value were both 2 mg/L. Only two . strains (MIC = 2 mg/L) and one . strain (MIC = 0.5 mg/L) were identified as carrying mobilized polymyxin resistant gene ., and .. All genes were located in the chromosome. This is the first report that the downstream region of -3.42 was the truncated -like gene separated by the insertion sequences of IS (1,674 bp) and IS (1,084 bp). Analysis of epidemiology of -positive genomes from GenBank database showed that the genus and the aquatic environment might be the potential container and reservoir of . By the whole-genome sequencing and qRT-PCR, we inferred that the sequence differences in the AAA domain of MlaF protein and its expression level among these three species might be involved in the development of polymyxin resistance. Our study provided evidences of the possible mechanism for the variety of polymyxin susceptibility in different species of the genus and a theoretical basis for the surveillance of the aquatic environment.
PubMed: 36386612
DOI: 10.3389/fmicb.2022.1030564