Characterization of tryptanthrin as an antibacterial reagent inhibiting Vibrio splendidus.

Isolates of Vibrio splendidus are ubiquitously presented in various marine environments, and they can infect diverse marine culture animals, leading to high mortality and economic loss. Therefore, a control strategy of the infection caused by V. splendidus is urgently recommended. Tryptanthrin is a naturally extracted bioactive chemical with antimicrobial activity to other bacteria. In this study, the effects of tryptanthrin on the bacterial growth and virulence-related factors of one pathogenic strain V. splendidus AJ01 were determined. Tryptanthrin (10 µg/mL) could completely inhibit the growth of V. splendidus AJ01. The virulence-related factors of V. splendidus AJ01 were affected in the presence of tryptanthrin. Tryptanthrin resulted an increase in biofilm formation, but lead to reduction in the motility and hemolytic activity of V. splendidus cells. In the cells treated with tryptanthrin, two distinctly differentially expressed extracellular proteins, proteases and flagellum, were identified using SDS-PAGE combined with LC-MS. Real-time reverse transcriptase PCR confirmed that the genes involved in the flagellar formation and hemolysin decreased, whereas specific extracellular proteases and the genes involved in the biofilm formation were upregulated. Two previously annotated luxOVs genes were cloned, and their expression levels were analyzed at different cell densities. Molecular docking was performed to predict the interaction between LuxOVs and ATP/tryptanthrin. The two sigma-54-dependent transcriptional regulators showed similar ATP or tryptanthrin binding capacity but with different sites, and the direct competitive binding between ATP and tryptanthrin was present only in their binding to LuxO1. These results indicated that tryptanthrin can be used as a bactericide of V. splendidus by inhibiting the growth, bacterial flagella, and extracellular proteases, but increasing the biofilm. Sigma-54-dependent transcriptional regulator, especially the quorum sensing regulatory protein LuxO1, was determined to be the potential target of tryptanthrin. KEY POINTS: • Tryptanthrin inhibited the growth of V. splendidus in a dose-dependent manner. • The effect of tryptanthrin on the virulence factors of V. splendidus was characterized. • LuxO was the potential target for tryptanthrin based on molecular docking.

Expression of the AHPND Toxins PirAvp and PirBvp Is Regulated by Components of the Vibrio parahaemolyticus Quorum Sensing (QS) System.

Acute hepatopancreatic necrosis disease (AHPND) in shrimp is caused by Vibrio strains that harbor a pVA1-like plasmid containing the pirA and pirB genes. It is also known that the production of the PirA and PirB proteins, which are the key factors that drive the observed symptoms of AHPND, can be influenced by environmental conditions and that this leads to changes in the virulence of the bacteria. However, to our knowledge, the mechanisms involved in regulating the expression of the pirA/pirB genes have not previously been investigated. In this study, we show that in the AHPND-causing Vibrio parahaemolyticus 3HP strain, the pirAvp and pirBvp genes are highly expressed in the early log phase of the growth curve. Subsequently, the expression of the PirAvp and PirBvp proteins continues throughout the log phase. When we compared mutant strains with a deletion or substitution in two of the quorum sensing (QS) master regulators, luxO and/or opaR (luxOD47E, ΔopaR, ΔluxO, and ΔopaRΔluxO), our results suggested that expression of the pirAvp and pirBvp genes was related to the QS system, with luxO acting as a negative regulator of pirAvp and pirBvp without any mediation by opaRvp. In the promoter region of the pirAvp/pirBvp operon, we also identified a putative consensus binding site for the QS transcriptional regulator AphB. Real-time PCR further showed that aphBvp was negatively controlled by LuxOvp, and that its expression paralleled the expression patterns of pirAvp and pirBvp. An electrophoretic mobility shift assay (EMSA) showed that AphBvp could bind to this predicted region, even though another QS transcriptional regulator, AphAvp, could not. Taken together, these findings suggest that the QS system may regulate pirAvp/pirBvp expression through AphBvp.

Tryptanthrin, a potential biofilm inhibitor against toxigenic Vibrio cholerae, modulating the global quorum sensing regulator, LuxO.

Cholera caused by the Gram-negative bacterium Vibrio cholerae still remains a major health burden in developing countries due to its high transmissibility and multidrug resistance. Alternative strategies are in quest to curtail the disease focusing on antivirulent approaches, such as biofilm inhibition, which make bacteria more susceptible to antibiotic therapies. The biofilm state is important for V. cholerae pathogenesis and its persistence in the environment. In the present study, tryptanthrin, a phytochemical, has been identified as possessing strong anti-biofilm activity at sub MIC (2 µg ml-1) against V. cholerae. LuxO was identified as the putative target of tryptanthrin by molecular docking and real time analysis. The phytochemical was identified as safe and possessed synergistic action with ciprofloxacin, a commonly used quinolone antibiotic to treat cholera. Collectively, the study establishes the first report on the anti-biofilm property of tryptanthrin by targeting LuxO, which could serve as a potential antivirulent therapy to combat V. cholerae infections.

Characterization of quorum regulatory small RNAs in an emerging pathogen Vibrio fluvialis and their roles toward type VI secretion system VflT6SS2 modulation.

The type VI secretion system (T6SS) is essential for Gram-negative bacteria to antagonize a wide variety of prokaryotic and eukaryotic competitors and thus gain survival advantages. Two sets of T6SS have been found in Vibrio fluvialis, namely VflT6SS1 and VflT6SS2, among which VflT6SS2 is functionally expressed. The CqsA/LuxS-HapR quorum sensing (QS) system with CAI-1 and AI-2 as signal molecules can regulate VflT6SS2 by regulators LuxO and HapR, with LuxO repressing while HapR activating VflT6SS2. Quorum regulatory small RNAs (Qrr sRNAs) are Hfq-dependent trans-encoded sRNAs that control Vibrio quorum sensing. In V. fluvialis, Qrr sRNAs have not been characterized and their regulatory function is unknown. In this study, we first identified four Qrr sRNAs in V. fluvialis and demonstrated that these Qrr sRNAs are regulated by LuxO and involved in the modulation of VflT6SS2 function. On the one hand, Qrr sRNAs act on HapR, the activator of both the major and the auxiliary clusters of VflT6SS2, and then indirectly repress VflT6SS2. On the other hand, they directly repress VflT6SS2 by acting on tssB2 and tssD2_a, the first gene of the major cluster and the highly transcriptional one among the two units of the first auxiliary cluster, respectively. Our results give insights into the role of Qrr sRNAs in CAI-1/AI-2 based QS and VflT6SS2 modulation in V. fluvialis and further enhance understandings of the network between QS and T6SS regulation in Vibrio species.

Design of novel anti-quorum sensing peptides targeting LuxO to combat Vibrio cholerae pathogenesis.

Vibrio cholerae, the Gram-negative bacterium abruptly colonizes the human intestine causing diarrhea, employing quorum sensing (QS) system as the major survival technique for mediating biofilm formation, virulence, competence, etc. Two distinct QS systems coordinated by the auto-inducer molecules, cholera-specific CqsA/S system and universal LuxS/PQ system, operate in parallel converging into a common phosphorelay pathway involving LuxU and LuxO. The master regulatory proteins of the QS system, AphA and HapR regulate the biofilm formation based on cell density, whose expression is controlled by the global response regulator LuxO. At low cell density, activated LuxO indirectly represses HapR, favoring the virulence cascade expression. Rather at high cell densities, LuxO represses AphA expression subsequently blocking the expression of virulence factors. Hence, targeting LuxO would be a promising strategy to downregulate the virulence pathway and modulate the QS system. With this insight, the present study has been designed to intrude the interaction between LuxU and LuxO through in silico design of novel peptides and validation of these peptides through molecular simulations. QS peptides were designed using QSPred server by altering the template sequence representing the LuxU-LuxO interaction, among which PEP8 exhibited better interaction and stability with the target protein LuxO. These in silico designed novel peptides would serve as potential target-specific molecules that would inhibit the LuxU-LuxO interaction and modulate the QS system to restrict Vibrio cholerae pathogenesis. However, further in vitro validations would substantiate the efficacy of these novel QS peptides. Supplementary Information: The online version contains supplementary material available at 10.1007/s40203-023-00172-2.

CqsA/LuxS-HapR Quorum sensing circuit modulates type VI secretion system VflT6SS2 in Vibrio fluvialis.

Vibrio fluvialis is an emerging enteric pathogen of increasing public health threat. Two quorum sensing (QS) systems, VfqI-VfqR and CqsA/LuxS-HapR, and two type VI secretion systems (T6SSs), VflT6SS1 and VflT6SS2, have been identified in V. fluvialis. Whether there exists any correlation between the two systems is unclear. In this study, we found that CqsA/LuxS-HapR circuit regulator LuxO represses while HapR activates VflT6SS2. The effect of LuxO is more pronounced at low cell density and is HapR-dependent. Deletion of hapR abolished Hcp expression and alleviated antibacterial virulence. However, these effects were rescued by HapR-expressing plasmid. Reporter fusion analyses showed that HapR is required for the promoter activities of VflT6SS2. Sequence inspection of the major cluster promoter revealed two potential Motif 1 HapR binding sites, and their bindings to HapR were confirmed by both electrophoretic mobility shift assay (EMSA) and DNase I footprinting assay. Meanwhile, two single Motif 2 sites were identified in tssD2_a (hcpA) and tssD2_b (hcpB) promoter regions of the orphan cluster which are less conserved and displayed lower affinities to HapR. Together, our study demonstrated that CqsA/LuxS-HapR QS manipulate VflT6SS2 in V. fluvialis, and this finding will enhance our understanding of possible crosstalk between T6SS and QS in microbes.

Luxación de cadera asociada a fractura del extremo proximal de fémur: reporte de caso y revisión del tema / Hip dislocation associated with fracture of the proximal end of the femur: case report and literature review / Luxação do quadril associada a fratura da extremidade proximal do fêmur: relato de caso e revisão da literatura

Las luxaciones traumáticas de cadera son poco frecuentes, y es excepcional la asociación lesional con fracturas del extremo proximal de fémur, habitualmente producidas por accidentes de alta energía. Un correcto diagnóstico, y tratamiento adecuado de la fractura, es la conducta ideal para disminuir las complicaciones. Presentamos el caso de un paciente masculino 49 años trabajador de la construcción que, en un accidente de tránsito, sufre una luxación de cadera asociado a fractura de cuello femoral, con excepcional presentación radiológica, con lesión del nervio CPE (ciático poplíteo externo), en que se realizó artroplastia total de cadera, con buena evolución y rehabilitación, retornando a su actividad laboral a los 11 meses del accidente. A propósito de este caso, realizamos una revisión bibliográfica para evaluar el tratamiento propuesto, el ideal, y pronóstico funcional de estas lesiones.

Traumatic hip dislocations are rare, and associated injuries involving fractures of the proximal end of the femur, usually as a result of high-energy accidents, are exceptional. A correct diagnosis and adequate treatment of the fracture is the most appropriate way to reduce complications. We present the case of a 49-year-old male construction worker who, as a result of a traffic accident, suffers from a hip dislocation associated with a femoral neck fracture, with exceptional radiological presentation, with injury to the EPS (External Popliteal Sciatic) nerve. Total hip arthropathy was performed, with good evolution and rehabilitation, and patient returned to work 11 months after the accident. In this particular case, we carried out a bibliographic review to evaluate the proposed treatment, the ideal treatment, and the functional prognosis of these injuries.

As luxações traumáticas do quadril são raras, e a associação de lesão com fraturas da extremidade proximal do fêmur, geralmente causada por acidentes de alta energia, é excepcional. O diagnóstico correto e o tratamento adequado da fratura é a abordagem ideal para reduzir as complicações. Apresentamos o caso de um operário da construção civil, 49 anos, que, em acidente de trânsito, sofre luxação de quadril associada a fratura do colo do fêmur, com apresentação radiológica excepcional, com lesão do nervo ciático poplíteo externo (CPE), em onde foi realizada a artroplastia total do quadril, com boa evolução e reabilitação, retornando ao trabalho 11 meses após o acidente. Em relação a este caso, realizamos uma revisão bibliográfica para avaliar o tratamento proposto, o ideal e o prognóstico funcional dessas lesões.

Circulation of a Quorum-Sensing-Impaired Variant of Vibrio cholerae Strain C6706 Masks Important Phenotypes.

Vibrio cholerae, the causative agent of cholera, is a model organism for studying virulence regulation, biofilm formation, horizontal gene transfer, and the cell-to-cell communication known as quorum sensing (QS). As in any research field, discrepancies between data from diverse laboratories are sometimes observed for V. cholerae. Such discrepancies are often caused by the use of diverse patient or environmental isolates. In this study, we investigated the inability of a few laboratories to reproduce high levels of natural transformation, a mode of horizontal gene transfer that is specifically induced on chitinous surfaces. This irreproducibility was mostly related to one specific isolate of V. cholerae: the O1 El Tor C6706 strain. C6706 was previously described as QS proficient, an important prerequisite for the induction of natural competence for transformation. To elucidate the underlying problem, we collected seven isolates of the same C6706 strain from different research laboratories in North America and Europe and compared their phenotypes. Importantly, we observed a split response with respect to QS-related gene expression, including chitin-induced natural competence and type VI secretion (T6S). While approximately half of the strains behaved as reported for several other O1 El Tor pandemic isolates that are commonly studied in the laboratory, the other half were significantly impaired in QS-related expression patterns. This impairment was caused by a mutation in a QS-related gene (luxO). We conclude that the circulation of such QS-impaired wild-type strains is responsible for masking several important phenotypes of V. cholerae, including natural competence for transformation and T6S. IMPORTANCE Phenotypic diversity between laboratory-domesticated bacterial strains is a common problem and often results in the failed reproduction of published data. However, researchers rarely compare such strains to elucidate the underlying mutation(s). In this study, we tested one of the best-studied V. cholerae isolates, O1 El Tor strain C6706 (a patient isolate from Peru), with respect to two main phenotypes: natural competence for transformation and type VI secretion. We recently demonstrated that the two phenotypes are coregulated and specifically induced upon the growth of pandemic V. cholerae O1 El Tor strains on chitinous surfaces. We provide evidence that of seven C6706 strains collected from different laboratories, four were impaired in the tested phenotypes due to a mutation in a QS gene. Collectively, our data indicate that the circulation of such a mutated wild-type strain of C6706 might have had important consequences for QS-related data.

Single Nucleotide Polymorphisms in Regulator-Encoding Genes Have an Additive Effect on Virulence Gene Expression in a Vibrio cholerae Clinical Isolate.

Vibrio cholerae is the etiological agent of the infectious disease cholera, which is characterized by vomiting and severe watery diarrhea. Recently, V. cholerae clinical isolates have demonstrated increased virulence capabilities, causing more severe symptoms with a much higher rate of disease progression than previously observed. We have identified single nucleotide polymorphisms (SNPs) in four virulence-regulatory genes (hapR, hns, luxO, and vieA) of a hypervirulent V. cholerae clinical isolate, MQ1795. Herein, all SNPs and SNP combinations of interest were introduced into the prototypical El Tor reference strain N16961, and the effects on the production of numerous virulence-related factors, including cholera toxin (CT), the toxin-coregulated pilus (TCP), and ToxT, were analyzed. Our data show that triple-SNP (hapR hns luxO and hns luxO vieA) and quadruple-SNP combinations produced the greatest increases in CT, TCP, and ToxT production. The hns and hns luxO SNP combinations were sufficient for increased TCP and ToxT production. Notably, the hns luxO vieA triple-SNP combination strain produced TCP and ToxT levels similar to those of MQ1795. Certain SNP combinations (hapR and hapR vieA) had the opposite effect on CT, TCP, and ToxT expression. Interestingly, the hns vieA double-SNP combination strain increased TCP production while decreasing CT production. Our findings suggest that SNPs identified in the four regulatory genes, in various combinations, are associated with increased virulence capabilities observed in V. cholerae clinical isolates. These studies provide insight into the evolution of highly virulent strains. IMPORTANCE Cholera, an infectious disease of the small intestine caused by the aquatic bacterium Vibrio cholerae, often results in vomiting and acute watery diarrhea. If left untreated or if the response is too slow, the symptoms can quickly lead to extreme dehydration and ultimately death of the patient. Recent anecdotal evidence of cholera patients suffering from increasingly severe symptoms and of disease progression at a much higher rate than previously observed has emerged. As recent cholera outbreaks caused by increasingly virulent strains have resulted in higher mortality rates, the need to investigate the mechanism(s) allowing this observed increased virulence is apparent. The significance of our research is in identifying the mechanism for increased virulence capabilities, which will allow the development of a model that will greatly enhance our understanding of cholera disease and V. cholerae pathogenesis, leading to broader biomedical impacts, as cholera serves as a model for other enteric diarrheal diseases.

Importancia médico legal de las complicaciones observadas en la fractura de Monteggia: Reporte de caso / Medico-legal importance of the complications observed in Monteggia's fracture

Resumen La Fractura de Monteggia es una lesión caracterizada por una fractura del cúbito en su porción proximal o media junto con una luxación de la cabeza del radio. (1) Es una lesión poco frecuente que representa entre el 5 y el 7% de las fracturas del antebrazo, a pesar de su rareza, siempre ha sido considerada de gran importancia por las comorbilidades que pueden acompañarla, bien por ser tratadas de forma inadecuada o por retraso en su tratamiento médico. Cuando no se diagnostica y trata a tiempo, puede quedar como secuela una limitación de la movilidad articular y una incapacidad funcional importante en la extremidad traumatizada. (2) Es por esta razón que se decide realizar el presente artículo el cual pretende reflejar la importancia de las complicaciones presentadas en la Fractura de Monteggia, al momento de la valoración médico legal, pudiendo requerir incapacidad temporal y permanente dado al tiempo que toma su recuperación, la limitación a la movilización posterior al manejo médico y el dolor residual que puede presentar.

Abstract The Monteggia Fracture is an injury characterized by a fracture of the proximal or middle portion of the ulna with a dislocation of the head of the radius. (1) It is a rare injury and represents between 5 and 7% of forearm fractures. Despite its rarity, it has always been considered of great importance due to the comorbidities that can accompany it, either due to being treated inadequately or due to delay in your medical treatment. When it is not diagnosed and treated in time, a limitation of joint mobility and a significant functional disability in the traumatized limb can remain as a consequence. (2) It is for this reason that we decided to carry out this article which reflect the importance of the complication of the Monteggia Fracture, at the time of the legal evaluation, which may require temporary and permanent disability given to the time it takes its recovery, the limitation to mobilization after medical management and the residual pain that it may present.