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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 -
Revista Chilena de Infectologia :... Aug 2016
Topics: Humans; Polymerase Chain Reaction; Vibrio
PubMed: 27905630
DOI: 10.4067/S0716-10182016000400011 -
Archives of Microbiology Apr 2023The type VI secretion system (T6SS) is important for interbacterial competition and virulence in Vibrio species. It is generally agreed that T6SS provides a fitness...
The type VI secretion system (T6SS) is important for interbacterial competition and virulence in Vibrio species. It is generally agreed that T6SS provides a fitness advantage to Vibrios. Some Vibrio species possess one, while others possess two T6SSs. Even within the same Vibrio species, different strains can harbor a variable number of T6SSs. Such is the case in V. fluvialis, an opportunistic human pathogen, that some V. fluvialis strains do not harbor T6SS1. This study found that Amphritea, Marinomonas, Marinobacterium, Vibrio, Photobacterium, and Oceanospirillum species have genes encoding V. fluvialis T6SS1 homologs. The cladogram of T6SS1 genes suggested that these genes appeared to be horizontally acquired by V. fluvialis, V. furnissii, and some other Vibrio species, when compared with the species tree. Codon insertions, codon deletions, nonsense mutations, and the insertion sequence are found in many genes, such as clpV1, tssL1, and tssF1, which encode structure components of T6SS1 in V. furnissii and V. fluvialis. Codon deletion events are more common than codon insertion, insertion sequence disruption, and nonsense mutation events in genes that encode components of T6SS1. Similarly, codon insertions and codon deletions are found in genes relevant to T6SS2, including tssM2, vgrG2 and vasH, in V. furnissii and V. fluvialis. These mutations are likely to disable the functions of T6SSs. Our findings indicate that T6SS may have a fitness disadvantage in V. furnissii and V. fluvialis, and the loss of function in T6SS may help these Vibrio species to survive under certain conditions.
Topics: Humans; DNA Transposable Elements; Vibrio; Genomics; Mutation
PubMed: 37101014
DOI: 10.1007/s00203-023-03557-1 -
International Journal of Food... Jun 2022Vibrio fluvialis is an emerging foodborne pathogen that causes severe infections. Serotyping based on surface polysaccharide antigens is important for the clinical...
Vibrio fluvialis is an emerging foodborne pathogen that causes severe infections. Serotyping based on surface polysaccharide antigens is important for the clinical detection and epidemiological surveillance of pathogens such as V. fluvialis. For example, variation of the O-antigen, which is highly polymorphic and is responsible for the majority of antigenic variability on the bacterial cell surface, provides the basis for serotyping of Gram-negative bacteria. Currently, there has been no analysis of the O-antigen gene clusters in V. fluvialis. In this study, the putative O-antigen gene clusters of 18 V. fluvialis serogroups (O1-O18), which exhibit a high level diversity, were analyzed by whole-genome sequencing. A microsphere-based suspension array (MSA) based on O-serogroup-specific genes was developed for identification of V. fluvialis strains O1-O18 and evaluated for specificity and sensitivity in double-blind tests. Furthermore, analysis of 62 publicly available V. fluvialis genomes identified 13 new O-antigen gene cluster types. The detection sensitivity was determined to be 10 ng for genomic DNA and 10 CFU for pure cultures. When testing simulated samples in an oyster background, 2 to 20 CFU per gram inoculated could be detected after enrichment using this method. Our work provides an efficient tool for rapid detection and identification of V. fluvialis serogroups from clinical and environmental samples, with the potential for use in epidemiological investigations and food safety applications.
Topics: Multigene Family; O Antigens; Serotyping; Vibrio
PubMed: 35395487
DOI: 10.1016/j.ijfoodmicro.2022.109665 -
Archives of Microbiology Jul 2022Vibrio fluvialis is an opportunistic waterborne and seafood-borne enteric pathogen capable of causing severe diarrhea leading to death. This pathogen is endemic to...
Draft-genome analysis provides insights into the virulence properties and genome plasticity of Vibrio fluvialis organisms isolated from shrimp farms and Turag river in Bangladesh.
Vibrio fluvialis is an opportunistic waterborne and seafood-borne enteric pathogen capable of causing severe diarrhea leading to death. This pathogen is endemic to Bangladesh, a country which is a major producer of cultured shrimp and wild-caught prawns. In this study, we carried out whole-genome sequencing of three V. fluvialis organisms isolated from shrimp farm and river sediment showing strong pathogenic characteristics in vivo and in vitro and compared their genomes against other V. fluvialis and related pathogenic species to glean insights into their potential as pathogens. Numerous virulence-associated genes including hemolysins, cytolysins, three separate Type IV pili, Types II and VI secretion systems, biofilm, and the V. cholerae pathogenesis regulating gene, toxR, were identified. Moreover, we found strain S-10 to have the propensity to acquire antibiotic resistance genes through horizontal gene transfer. These findings indicate that shrimp farms and rivers could be potential sources of V. fluvialis organisms which are an infection threat of public health concern.
Topics: Aquaculture; Bangladesh; Rivers; Seafood; Vibrio; Vibrio cholerae; Virulence
PubMed: 35895240
DOI: 10.1007/s00203-022-03128-w -
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 -
Frontiers in Microbiology 2017is an emerging foodborne pathogen of increasing public health concern. The mechanism(s) that contribute to the bacterial survival and disease are still poorly...
is an emerging foodborne pathogen of increasing public health concern. The mechanism(s) that contribute to the bacterial survival and disease are still poorly understood. In other bacterial species, type VI secretion systems (T6SSs) are known to contribute to bacterial pathogenicity by exerting toxic effects on host cells or competing bacterial species. In this study, we characterized the genetic organization and prevalence of two T6SS gene clusters (VflT6SS1 and VflT6SS2) in . VflT6SS2 harbors three "orphan" modules and was more prevalent than VflT6SS1 in our isolates. We showed that VflT6SS2 is functionally active under low (25°C) and warm (30°C) temperatures by detecting the secretion of a T6SS substrate, Hcp. This finding suggests that VflT6SS2 may play an important role in the survival of the bacterium in the aquatic environment. The secretion of Hcp is growth phase-dependent and occurs in a narrow range of the growth phase (OD from 1.0 to 2.0). Osmolarity also regulates the function of VflT6SS2, as evidenced by our finding that increasing salinity (from 170 to 855 mM of NaCl) and exposure to high osmolarity KCl, sucrose, trehalose, or mannitol (equivalent to 340 mM of NaCl) induced significant secretion of Hcp under growth at 30°C. Furthermore, we found that although VflT6SS2 was inactive at a higher temperature (37°C), it became activated at this temperature if higher salinity conditions were present (from 513 to 855 mM of NaCl), indicating that it may be able to function under certain conditions in the infected host. Finally, we showed that the functional expression of VflT6SS2 is associated with anti-bacterial activity. This activity is Hcp-dependent and requires , a transcriptional regulator of T6SS. In sum, our study demonstrates that VflT6SS2 provides with an enhanced competitive fitness in the marine environment, and its activity is regulated by environmental signals, such as temperature and osmolarity.
PubMed: 28424671
DOI: 10.3389/fmicb.2017.00528 -
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