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Gut Microbes 2022is a halophilic Gram-negative bacterium regarded as an emerging unusual enteric pathogen of increasing public health concern. Our previous work has identified two type...
is a halophilic Gram-negative bacterium regarded as an emerging unusual enteric pathogen of increasing public health concern. Our previous work has identified two type VI secretion systems (T6SSs) in , VflT6SS1, and VflT6SS2, and the latter is functional in mediating interbacterial competitiveness. However, its antibacterial effectors remain to be clarified. In this work, we focused on a new potential effector/immunity pair TssI2/TsiI2. Bioinformatics analysis revealed that the C-terminal domain of TssI2 belongs to a widespread family of pesticin, and its antibacterial toxicity and corresponding protection by TsiI2 were proved via bacterial killing assays, and their action sites were localized to the periplasm of bacterial cells. The interaction of TssI2 and TsiI2 was demonstrated by the bacterial adenylate cyclase two-hybrid, protein pull-down and isothermal titration calorimetry assays. Site-directed mutagenesis demonstrated that, in addition to Glu-844, Thr-863, and Asp-869, which correspond to three reported residues in pesticin of , additional residues including Phe-837, Gly-845, Tyr-851, Gly-867, Gln-963, Trp-975, and Arg-1000 were also proved to be crucial to the bactericidal activity of TssI2. Muramidase/lysozyme-related peptidoglycan (PG) hydrolase activities of TssI2 and its variants were validated with permeabilized cells and purified PG substrate. Based on sequence homologies at C-terminals in various isolates, TssI2 was subdivided into five clusters (12-22% identity among them), and the antibacterial activities of representative effectors from other four Clusters were also confirmed through periplasmic over-expression in host. Two selected cognate immunities were proved to confer protection against the toxicities of their effectors. Additionally, TsiI2, which belongs to Cluster I, exhibited cross-protection to effector from Cluster V. Together, current findings expand our knowledge of the diversity and consistency of evolved VgrG effectors in and on how VflT6SS2 mediates a competitive advantage to gain a better survival.
Topics: Type VI Secretion Systems; Periplasm; Muramidase; Escherichia coli; Peptidoglycan; Adenylyl Cyclases; Gastrointestinal Microbiome; Bacterial Proteins; Anti-Bacterial Agents
PubMed: 36288406
DOI: 10.1080/19490976.2022.2136460 -
Iranian Journal of Microbiology Oct 2022is a Gram-negative, bacillus-shaped, curved bacterium known as an emerging pathogen. There are reports of outbreaks caused by this bacterium worldwide. Iran, especially...
BACKGROUND AND OBJECTIVES
is a Gram-negative, bacillus-shaped, curved bacterium known as an emerging pathogen. There are reports of outbreaks caused by this bacterium worldwide. Iran, especially Qom province, is an endemic region for gastrointestinal diseases caused by species. So, the aim was to isolate from clinical and environmental samples.
MATERIALS AND METHODS
During six months, 363 clinical and surface water samples were evaluated. The samples were cultured on specific media, and all incubated for 24 hours at 37°C. Suspicious colonies were evaluated by Gram staining and biochemical tests. The BD Phoenix automated microbiology system was used for the final confirmation of the isolated bacteria. Evaluation of antibiotic resistance of isolated strains was also performed according to CLSI standard.
RESULTS
Eight cases (2.2%) of , including seven from surface water samples (87.5%) and one from clinical samples (12.5%), were isolated. Based on antimicrobial susceptibility testing, all isolates were susceptible to amikacin, gentamicin, trimethoprim/sulfamethoxazole, ciprofloxacin, tetracycline, ceftazidime, and chloramphenicol. High-level resistance to ampicillin and amoxicillin/clavulanate was also observed. -infected patient had a mild fever, watery diarrhea, vomiting, nausea, and abdominal cramps that were manifested after drinking contaminated water or eating contaminated vegetables. The patient's symptoms recovered without antibiotic therapy after four days, resulting in self-limiting disease.
CONCLUSION
The current study is the first human case of infection isolated in Iran. Therefore, monitoring of water and food samples should be done routinely.
PubMed: 36531817
DOI: 10.18502/ijm.v14i5.10962 -
Frontiers in Cellular and Infection... 2021The study investigated the occurrence of antimicrobial resistance genes and virulence determinants in species recovered from different freshwater sheds in rustic...
The study investigated the occurrence of antimicrobial resistance genes and virulence determinants in species recovered from different freshwater sheds in rustic milieu. A total of 118 isolates comprising (n=41), (n=40) and (n=37) was identified by amplification of , and genes. The amplification of virulence genes indicated that . (, , , , and ) genes were detected in 12.5%, 32.5%, 45%, 37.5% and 10% respectively. . genes (, and ) were harboured in 48.8%, 14.6% and 19.5% isolates congruently. The other virulence genes that include and were observed in 63.1% and 29% of isolates belonging to . . With the exceptions of imipenem, meropenem and ciprofloxacin, most isolates exhibited more than 50% resistance to antibiotics. The antimicrobial resistance was more prevalent for polymyxin B (100%), azithromycin (100%) and least in ciprofloxacin (16.1%). Multiple antibiotic resistance index range was 0.3 and 0.8 with most isolates showing MARI of 0.8. The TEM, AmpC, GES, IMP, OXA-48 and KPC genes were detected in 53.3%, 42%, 29.6%, 16.6%, 15%, 11.3% and 5.6% of the isolates. Non-beta lactamases such as streptomycin resistance ( and ), gentamicin resistance () and quinolone resistance gene () were found in 5.2%, 44.3%, 26% and 2.8%. Chloramphenicol resistance genes ( and ) were found in 5.2% and 44.3% among the isolates. Our findings reveal the presence of antimicrobial resistance genes and virulent species in aquatic environment which can have potential risk to human and animal's health.
Topics: Animals; Anti-Bacterial Agents; Drug Resistance, Microbial; Fresh Water; Humans; Microbial Sensitivity Tests; Vibrio; Virulence
PubMed: 34490150
DOI: 10.3389/fcimb.2021.732001 -
Biochemistry and Biophysics Reports Sep 2022V. fluvialis is an emerging foodborne pathogen and could cause cholera-like gastroenteritis syndrome and poses a potential threat to public health. VflT6SS2 is a...
V. fluvialis is an emerging foodborne pathogen and could cause cholera-like gastroenteritis syndrome and poses a potential threat to public health. VflT6SS2 is a functionally active type VI secretion system (T6SS) in which confers bactericidal activity. VflT6SS2 is composed of one major cluster and three - orphan clusters. Previously, we identified two quorum sensing (QS) systems CqsA/LuxS-HapR and VfqI-VfqR in and demonstrated that the former regulates VflT6SS2. However, whether VfqI-VfqR QS regulates VflT6SS2 is unknown. In this study, we showed that the mRNA abundances of VflT6SS2 2 (), 2 () and 2 () were all significantly decreased in VfqI or/and VfqR deletion mutant(s). Consistently, Hcp expression/secretion was reduced too in these mutants. Complementation assay with VfqR mutant further confirmed that the reduced Hcp expression/secretion and impaired antibacterial virulence are restored by introducing VfqR-expressing plasmid. Reporter fusion analyses revealed that VfqR modulates the promoter activities of VflT6SS2. Bioinformatical prediction and further reporter fusion assay in supported that VfqR acts as a transcriptional factor to bind and regulate the gene expression of the VflT6SS2 major cluster. However, VfqR seems to promote transcription of (2) in the orphan clusters through elevating the expression of which is encoded by the VflT6SS2 major cluster. Additionally, we found that the regulation intensity of VfqR on VflT6SS2 is weaker than that of HapR. In conclusion, our current study disclosed that in , VfqI-VfqR circuit upregulates the expression and function of VflT6SS2 by directly or indirectly activating its transcription. These findings will enhance our understanding of the complicated regulatory network between QS and T6SS in .
PubMed: 35669988
DOI: 10.1016/j.bbrep.2022.101282 -
IScience May 2024is an emerging foodborne pathogen that produces VFH ( hemolysin) and δVFH (delta- hemolysin). The function of δVFH is unclear. Currently, no pathogenic . from deep...
is an emerging foodborne pathogen that produces VFH ( hemolysin) and δVFH (delta- hemolysin). The function of δVFH is unclear. Currently, no pathogenic . from deep sea has been reported. In this work, a deep-sea . isolate (V13) was examined for pathogenicity. V13 was most closely related to ATCC 33809, a human isolate, but possessed 262 unique genes. V13 caused lethal infection in fish and induced pyroptosis involving activation of the NLRP3 inflammasome, caspase 1 (Casp1), and gasdermin D (GSDMD). V13 defective in VFH or VFH plus δVFH exhibited significantly weakened cytotoxicity. Recombinant δVFH induced NLRP3-Casp1-GSDMD-mediated pyroptosis in a manner that depended on K efflux and intracellular Ca accumulation. δVFH bound several plasma membrane lipids, and these bindings were crucial for δVFH cytotoxicity. Together these results provided new insights into the function of δVFH and the virulence mechanism of .
PubMed: 38650982
DOI: 10.1016/j.isci.2024.109558 -
Journal of Tropical Medicine 2023The noncholera spp. which cause vibriosis are abundantly found in our water ecosystem. These bacteria could negatively affect both humans and animals. To date, there is...
BACKGROUND
The noncholera spp. which cause vibriosis are abundantly found in our water ecosystem. These bacteria could negatively affect both humans and animals. To date, there is a paucity of information available on the existence and pathogenicity of this particular noncholera spp. in Malaysia in comparison to their counterpart, .
METHODS
In this study, we extracted retrospective data from Malaysian surveillance database. Analysis was carried out using WHONET software focusing noncholera spp. including , , , , (), , , and .
RESULTS
Here, we report the first distribution and prevalence of these species isolated in Malaysia together with the antibiotic sensitivity profile based on the species. We found that is the predominant species isolated in Malaysia. Noticeably, across the study period, is becoming more prevalent, as compared to . In addition, this study also reports the first isolation of pathogenic from stool in Malaysia.
CONCLUSION
These data represent an important step toward understanding the potential emergence of noncholera spp. outbreaks.
PubMed: 37274080
DOI: 10.1155/2023/2716789 -
Plants (Basel, Switzerland) Aug 2022L. essential oil (cumin EO) was studied for its chemical composition, antioxidant and vibriocidal activities. Inhibition of biofilm formation and secretion of some...
L. essential oil (cumin EO) was studied for its chemical composition, antioxidant and vibriocidal activities. Inhibition of biofilm formation and secretion of some virulence properties controlled by the quorum sensing system in and strains were also reported. The obtained results showed that cuminaldehyde (44.2%) was the dominant compound followed by β-pinene (15.1%), γ-terpinene (14.4%), and -cymene (14.2%). Using the disc diffusion assay, cumin EO (10 mg/disc) was particularly active against all fifteen species, and the highest diameter of growth inhibition zone was recorded against (41.33 ± 1.15 mm), (39.67 ± 0.58 mm), and (36.67 ± 0.58 mm). At low concentration (MICs value from 0.023-0.046 mg/mL), cumin EO inhibited the growth of all strains, and concentrations as low as 1.5 mg/mL were necessary to kill them (MBCs values from 1.5-12 mg/mL). Using four antioxidant assays, cumin EO exhibited a good result as compared to standard molecules (DPPH = 8 ± 0.54 mg/mL; reducing power = 3.5 ± 0.38 mg/mL; β-carotene = 3.8 ± 0.34 mg/mL; chelating power = 8.4 ± 0.14 mg/mL). More interestingly, at 2x MIC value, cumin EO inhibited the formation of biofilm by (9.96 ± 1%), (15.45 ± 0.7%), (14.9 ± 0.4%), and (18.14 ± 0.3%). In addition, cumin EO and cuminaldehyde inhibited the production of violacein on Lauria Bertani medium (19 mm and 35 mm, respectively). Meanwhile, 50% of violacein inhibition concentration (VIC) was about 2.746 mg/mL for cumin EO and 1.676 mg/mL for cuminaldehyde. Moreover, elastase and protease production and flagellar motility in were inhibited at low concentrations of cumin EO and cuminaldehyde. The adopted in-silico approach revealed good ADMET properties as well as a high binding score of the main compounds with target proteins (1JIJ, 2UV0, 1HD2, and 3QP1). Overall, the obtained results highlighted the effectiveness of cumin EO to prevent spoilage with species and to interfere with the quorum sensing system in Gram-negative bacteria by inhibiting the flagellar motility, formation of biofilm, and the secretion of some virulence enzymes.
PubMed: 36079620
DOI: 10.3390/plants11172236 -
Microbial Genomics Feb 2022is a food-borne pathogen with epidemic potential that causes cholera-like acute gastroenteritis and sometimes extraintestinal infections in humans. However, research on...
is a food-borne pathogen with epidemic potential that causes cholera-like acute gastroenteritis and sometimes extraintestinal infections in humans. However, research on its genetic diversity and pathogenicity-related genetic elements based on whole genome sequences is lacking. In this study, we collected and sequenced 130 strains of from 14 provinces of China, and also determined the susceptibility of 35 of the strains to 30 different antibiotics. Combined with 52 publicly available genomes, we inferred the population structure and investigated the characteristics of pathogenicity-related factors. The strains exhibited high levels of homologous recombination and were assigned to two major populations, VflPop1 and VflPop2, according to the different compositions of their gene pools. VflPop2 was subdivided into groups 2.1 and 2.2. Except for VflPop2.2, which consisted only of Asian strains, the strains in VflPop1 and VflPop2.1 were distributed in the Americas, Asia and Europe. Analysis of the pathogenicity potential of showed that most of the identified virulence-related genes or gene clusters showed high prevalence in , except for three mobile genetic elements: pBD146, ICEInd1 and MGIInd1, which were scattered in only a few strains. A total of 21 antimicrobial resistance genes were identified in the genomes of the 182 strains analysed in this study, and 19 (90%) of them were exclusively present in VflPop2. Notably, the tetracycline resistance-related gene (35) was present in 150 (95%) of the strains in VflPop2, and in only one (4%) strain in VflPop1, indicating it was population-specific. In total, 91% of the 35 selected strains showed resistance to cefazolin, indicating has a high resistance rate to cefazolin. Among the 15 genomes that carried the previously reported drug resistance-related plasmid pBD146, 11 (73%) showed resistance to trimethoprim-sulfamethoxazole, which we inferred was related to the presence of the gene in the plasmid. On the basis of the population genomics analysis, the genetic diversity, population structure and distribution of pathogenicity-related factors of were delineated in this study. The results will provide further clues regarding the evolution and pathogenic mechanisms of , and improve our knowledge for the prevention and control of this pathogen.
Topics: Anti-Bacterial Agents; Cefazolin; Humans; Metagenomics; Vibrio; Virulence; Virulence Factors
PubMed: 35212619
DOI: 10.1099/mgen.0.000769 -
Microbiology Spectrum Feb 2023Vibrio cholerae can utilize a type VI secretion system (T6SS) to increase its intra- and interspecies competition. However, much still remains to be understood about the...
Vibrio cholerae can utilize a type VI secretion system (T6SS) to increase its intra- and interspecies competition. However, much still remains to be understood about the underlying mechanism of this intraspecies competition. In this study, we isolated an environmental V. cholerae strain E1 that lacked the typical virulence factors toxin-coregulated pilus and cholera toxin and that encoded a functional T6SS. We identified an evolved VgrG3 variant with a predicted C-terminal pesticin-like domain in V. cholerae E1, designated VgrG3. Using heterologous expression, protein secretion, and peptidoglycan-degrading assays, we demonstrated that VgrG3 is a T6SS-dependent effector harboring cell wall muramidase activity and that its toxicity can be neutralized by cognate immunity protein TsiV3. Site-directed mutagenesis proved that the aspartic acid residue at position 867 is crucial for VgrG3-mediated antibacterial activity. Bioinformatic analysis showed that genes encoding VgrG3-like homologs are distributed in species, are linked with T6SS structural genes and auxiliary genes, and the gene pair of V. cholerae probably evolved from Vibrio anguillarum and Vibrio fluvialis via homologous recombination. Through a time-lapse microscopy assay, we directly determined that cells accumulating VgrG3 disrupted bacterial division, while the cells continued to increase in size until the loss of membrane potential and cell wall breakage and finally burst. The results of the competitive killing assay showed that VgrG3 contributes to V. cholerae interspecies competition. Collectively, our study revealed a novel T6SS E-I pair representing a new T6SS toxin family which allows V. cholerae to gain dominance within polymicrobial communities by T6SS. The type VI secretion system used by a broad range of Gram-negative bacteria delivers toxic proteins to target adjacent eukaryotic and prokaryotic cells. Diversification of effector proteins determines the complex bacterium-bacterium interactions and impacts the health of hosts and environmental ecosystems in which bacteria reside. This work uncovered an evolved valine-glycine repeat protein G3, carrying a C-terminal pesticin-like domain (VgrG3), which has been suggested to harbor cell wall hydrolase activity and is able to affect cell division and the integrity of cell wall structure. Pesticin-like homologs constitute a family of T6SS-associated effectors targeting bacterial peptidoglycan which are distributed in species, and genetic loci of them are linked with T6SS structural genes and auxiliary genes. T6SS-delivered VgrG3 mediated broad-spectrum antibacterial activity for several microorganisms tested, indicating that VgrG3-mediated antimicrobial activity is capable of conferring bacteria a competitive advantage over competitors in the same niches.
Topics: Type VI Secretion Systems; Vibrio cholerae; Peptidoglycan; Ecosystem; Bacterial Proteins; Anti-Bacterial Agents; Cell Wall
PubMed: 36625646
DOI: 10.1128/spectrum.04267-22 -
Internal Medicine (Tokyo, Japan) Mar 2024Vibrio fluvialis is a bacterium that can be found in both seawater and freshwater, and it is responsible for causing gastroenteritis and cholangitis. V. fluvialis...
Vibrio fluvialis is a bacterium that can be found in both seawater and freshwater, and it is responsible for causing gastroenteritis and cholangitis. V. fluvialis bacteremia has rarely been reported. We report a case of V. fluvialis bacteremia due to cholangitis in an immunocompetent adult who was exposed to seawater regularly as a sushi chef. The increased risk of V. fluvialis entry into the body resulting from frequent consumption of raw fish and regular exposure to seawater, bile outflow impairment caused by transient inflammation of the bile duct, and the presence of multiple bile acid resistance-related genes in V. fluvialis may lead to the development of acute cholangitis and subsequent bacteremia in immunocompetent patients.
PubMed: 38432963
DOI: 10.2169/internalmedicine.3078-23