Comparative pathogenomic analysis reveals a highly tetanus toxin-producing clade of Clostridium tetani isolates in Japan.

IMPORTANCE: C. tetani is a spore-forming, anaerobic bacterium that produces a toxin causing muscle stiffness and paralysis. Tetanus is preventable with the toxoid vaccine, but it remains a significant public health threat in regions with low vaccine coverage. However, there are relatively few isolates and limited genomic information available worldwide. In Japan, about 100 cases are reported each year, but there have been no nationwide surveys of isolates, and no genomic information from Japanese isolates has been published. In our study, we analyzed the genomes of 151 strains from a limited survey of soil in Kumamoto, Japan. Our findings revealed a high degree of genetic diversity, and we also identified a subset of strains that produced significantly more toxin, which provides new insights into the pathogenesis of tetanus. Our findings lay the foundation for future studies to investigate the distribution and evolution of C. tetani in Japan and neighboring countries.

[Tetanus: an immunopreventable disease]. / Tétanos: una enfermedad inmunoprevenible.

Tetanus is an infectious disease caused by a ubiquitous bacterium Clostridium tetani, that synthesizes and releasesa potent neurotoxin under anaerobic conditions, which is responsible for the clinical manifestations. As it is found in soil contaminated with animal and human excreta, it is difficult to eradicate but it may be prevented by immunization. Immunization rate has decreased in the last years, especially during the COVID-19 pandemic. We report two cases of tetanus, attended during 2022. A 39-year-old man whose entry route was a gunshot wound and he was discharged from the intensive care unit (ICU) and a second case of an 83-year-old woman with unknown entry point, who died during her ICU stay. The cases reported highlight that it is a life-threatening disease, its diagnosis is mainly clinical and it should be in the algorithm of differential diagnoses. We emphasize about the prompt treatment administration or consultation to a specialized healthcare center. The importance of this presentation is to show the severity of the disease, whose assessment is mainly clinical and should not escape the algorithm of differential diagnoses, emphasizing that treatment should be instituted early or when in doubt consult a specialized center. In addition to this, it is important to check theimmunization rate in our country, especially during thepandemic, becauseit is a vaccine-preventable disease.

El tétanos es causado por el Clostridium tetani, una bacteria ubicua que frente a condiciones de anaerobiosis puede sintetizar y liberar sus toxinas, responsables del cuadro clínico. Dado que es una bacteria que se encuentra en el suelo y en el tracto gastrointestinal de muchas especies, se trata de una enfermedad no erradicable pero si controlable a través de la inmunización para la prevención. Las tasas de inmunización han disminuido en los últimos años, evento que se ha acentuado durante la COVID-19. Se presentan a continuación dos casos clínicos ingresados durante el año 2022. El primero es un hombre de 39 años cuya puerta de entrada fue una herida de arma de fuego conevolución favorable y el segundo caso se trata de una mujer de 83 años sin puerta de entrada clara quien falleció durante su internación en terapia intensiva. La importancia de esta presentación es mostrar la gravedad de la enfermedad, cuyavaloración es principalmente clínica y no debe escapar al algoritmo de diagnósticos diferenciales, acentuando que se debe instaurar el tratamiento de forma precoz o frente a la duda consultar con un centro especializado. Asímismo, es importante revisar las tasas de inmunización en nuestro país y los cambios que se presentaron durante la pandemia, teniendo en cuenta, como se ha expuesto previamente, se trata de una enfermedad inmunoprevenible.

HLA-DR3 restricted environmental epitopes from the bacterium Clostridium tetani have T cell cross-reactivity to the SLE-related autoantigen SmD.

HLA-DR3 (DR3) is one of the dominant HLA-DR alleles associated with systemic lupus erythematosus (SLE) susceptibility. Our previous studies showed multiple intramolecular DR3 restricted T cell epitopes in the Smith D (SmD) protein, from which we generated a non-homologous, bacterial epitope mimics library. From this library we identified ABC247-261 Mimic as one new DR3 restricted bacterial T cell epitope from the ABC transporter ATP-binding protein in Clostridium tetani. It activated and induced autoreactive SmD66-80-specific T cells and induced autoantibodies to lupus-related autoantigens in vivo. Compared to healthy donors, SLE patients have a greater percentage of cross-reactive T cells to ABC247-261 Mimic and SmD66-80. In addition, we analyzed the ability of single DR3 restricted Tetanus toxoid (TT) T cell epitopes to induce autoimmune T cells. We found that the immunodominant TT epitope TT826-845 stimulated SmD66-80 reactive T cells but failed to induce persistent anti-SmD autoantibodies compared to the ABC247-261 Mimic. Thus, exposure to the ABC247-261 Mimic epitope may contribute to autoimmunity in susceptible DR3 individuals.

Tetanus, analysis of 29 cases

BackgroundTetanus disease is caused by Clostridium tetani, an anaerobe bacteria found in dust and soil. Once reached human body through damaged tissues, C. tetani releases several neurotoxins which block the inhibitory function, leading to an increased muscle tone, ultimately causing respiratory failure. Severe tetanus is a life-threatening disease, especially in low-income-regions.MethodsThis is a retrospective case-series study, undertaken at two hospitals of Vigo (population area 600,000 inhabitants). Tetanus cases were identified through the discharge databases of both hospitals between the years 1995–2019. Epidemiological and clinical data were obtained from the patient's medical records.ResultsA total of 33 cases were identified; median age was 67 years, and most of patients were women (n=16, 55.2%). Generalized tetanus was the most common clinical course, and neck stiffness was the most frequent symptom. A total of 25 patients (86%) were admitted to the Intensive Care Unit, 21 required invasive ventilation and 2 patients died.DiscussionThe incidence of tetanus was low but most of cases were severe. Mortality was slightly higher than previously reported. Interestingly, the deceased patients were old-women, consistent with previously reported research in high-income-regions, while mortality in low-income-countries concentrates in middle-aged men. (AU)

IntroducciónEl tétanos es causado por Clostridium tetani, bacteria anaerobia, ubicada en el suelo. Este microorganismo penetra a través de heridas y libera neurotoxinas que bloquean la función inhibitoria, produciendo espasticidad y fracaso respiratorio. Es una enfermedad grave, especialmente en regiones empobrecidas.MétodosSerie de casos realizada en dos hospitales vigueses (área 600.000 habitantes). Los casos fueron identificados mediante los sistemas de codificación entre 1995-2019. Los datos asistenciales se obtuvieron de la historia clínica.ResultadosSe identificaron 33 casos, mediana de edad, 67 años, la mayoría mujeres (n = 16, 55,2%). El tétanos generalizado fue la forma clínica predominante, la rigidez cervical el síntoma más común. Un total de 25 pacientes requirieron ingreso en UCI, 21 ventilación mecánica, dos fallecieron.DiscusiónEl número de casos fue bajo, pero la mayoría graves. La mortalidad fue ligeramente superior a la informada previamente. La mortalidad se concentró en mujeres ancianas, concordante con otros países desarrollados, mientras que la mortalidad en regiones no-desarrolladas se agrupa en varones de mediana edad. (AU)

Regulatory Networks Controlling Neurotoxin Synthesis in Clostridium botulinum and Clostridium tetani.

Clostridium botulinum and Clostridium tetani are Gram-positive, spore-forming, and anaerobic bacteria that produce the most potent neurotoxins, botulinum toxin (BoNT) and tetanus toxin (TeNT), responsible for flaccid and spastic paralysis, respectively. The main habitat of these toxigenic bacteria is the environment (soil, sediments, cadavers, decayed plants, intestinal content of healthy carrier animals). C. botulinum can grow and produce BoNT in food, leading to food-borne botulism, and in some circumstances, C. botulinum can colonize the intestinal tract and induce infant botulism or adult intestinal toxemia botulism. More rarely, C. botulinum colonizes wounds, whereas tetanus is always a result of wound contamination by C. tetani. The synthesis of neurotoxins is strictly regulated by complex regulatory networks. The highest levels of neurotoxins are produced at the end of the exponential growth and in the early stationary growth phase. Both microorganisms, except C. botulinum E, share an alternative sigma factor, BotR and TetR, respectively, the genes of which are located upstream of the neurotoxin genes. These factors are essential for neurotoxin gene expression. C. botulinum and C. tetani share also a two-component system (TCS) that negatively regulates neurotoxin synthesis, but each microorganism uses additional distinct sets of TCSs. Neurotoxin synthesis is interlocked with the general metabolism, and CodY, a master regulator of metabolism in Gram-positive bacteria, is involved in both clostridial species. The environmental and nutritional factors controlling neurotoxin synthesis are still poorly understood. The transition from amino acid to peptide metabolism seems to be an important factor. Moreover, a small non-coding RNA in C. tetani, and quorum-sensing systems in C. botulinum and possibly in C. tetani, also control toxin synthesis. However, both species use also distinct regulatory pathways; this reflects the adaptation of C. botulinum and C. tetani to different ecological niches.

Tetanus, analysis of 29 cases.

BACKGROUND: Tetanus disease is caused by Clostridium tetani, an anaerobe bacteria found in dust and soil. Once reached human body through damaged tissues, C. tetani releases several neurotoxins which block the inhibitory function, leading to an increased muscle tone, ultimately causing respiratory failure. Severe tetanus is a life-threatening disease, especially in low-income-regions. METHODS: This is a retrospective case-series study, undertaken at two hospitals of Vigo (population area 600,000 inhabitants). Tetanus cases were identified through the discharge databases of both hospitals between the years 1995-2019. Epidemiological and clinical data were obtained from the patient's medical records. RESULTS: A total of 33 cases were identified; median age was 67 years, and most of patients were women (n=16, 55.2%). Generalized tetanus was the most common clinical course, and neck stiffness was the most frequent symptom. A total of 25 patients (86%) were admitted to the Intensive Care Unit, 21 required invasive ventilation and 2 patients died. DISCUSSION: The incidence of tetanus was low but most of cases were severe. Mortality was slightly higher than previously reported. Interestingly, the deceased patients were old-women, consistent with previously reported research in high-income-regions, while mortality in low-income-countries concentrates in middle-aged men.

Regulation of Clostridium tetani Neurotoxin Expression by Culture Conditions.

BACKGROUND: Ensuring consistency of tetanus neurotoxin (TeNT) production by Clostridium tetani could help to ensure consistent product quality in tetanus vaccine manufacturing, ultimately contributing to reduced animal testing. The aim of this study was to identify RNA signatures related to consistent TeNT production using standard and non-standard culture conditions. METHODS: We applied RNA sequencing (RNA-Seq) to study C. tetani gene expression in small-scale batches under several culture conditions. RESULTS: We identified 1381 time-dependent differentially expressed genes (DEGs) reflecting, among others, changes in growth rate and metabolism. Comparing non-standard versus standard culture conditions identified 82 condition-dependent DEGs, most of which were specific for one condition. The tetanus neurotoxin gene (tetX) was highly expressed but showed expression changes over time and between culture conditions. The tetX gene showed significant down-regulation at higher pH levels (pH 7.8), which was confirmed by the quantification data obtained with the recently validated targeted LC-MS/MS approach. CONCLUSIONS: Non-standard culture conditions lead to different gene expression responses. The tetX gene appears to be the best transcriptional biomarker for monitoring TeNT production as part of batch-to-batch consistency testing during tetanus vaccine manufacturing.

Insights into Clostridium tetani: From genome to bioreactors.

Tetanus vaccination is of major importance for public health in most countries in the world. The World Health Organization indicated that 15,000 tetanus cases were reported in 2018 (Organization, World Health, 2019). Currently, vaccine manufacturers use tetanus toxin produced by Clostridium tetani fermentation in complex media. The complex components, commonly derived from animal sources, introduce potential variability in cultures. To achieve replicable fermentation and to avoid toxic or allergic reactions from animal-source compounds, several studies have tried to switch from complex to chemically defined media without affecting toxin titers. The present review introduces the current knowledge on i) C. tetani strain diversity, whole-genome sequences and metabolic networks; ii) toxin regulation and synthesis; and iii) culture media, cultivation processes and growth requirements. We critically reviewed the reported data on metabolism in C. tetani and completed comparative genomic and proteomic analyses with other Clostridia species. We integrated genomic data based on whole-genome sequence annotation, supplemented with cofactor specificities determined by protein sequence identity, in a new map of C. tetani central metabolism. This is the first data review that integrates insights from omics experiments on C. tetani. The overview of C. tetani physiology described here could provide support for the design of new chemically defined media devoid of complex sources for toxin production.

Rapid Detection of Clostridium tetani by Recombinase Polymerase Amplification Using an Exo Probe.

Tetanus is a potentially fatal public health illness resulted from the neurotoxins generated by Clostridium tetani. C. tetani is not easily culturable and culturing the relevant bacteria from infected wounds has rarely been useful in diagnosis; PCR-based assays can only be conducted at highly sophisticated laboratories. Therefore, a real-time recombinase polymerase amplification assay (Exo-RPA) was constructed to identify the fragments of the neurotoxin gene of C. tetani. Primers and the exo probe targeting the conserved region were designed, and the resulting amplicons could be detected in less than 20 min, with a detection limit of 20 copies/reaction. The RPA assay displayed good selectivity, and there were no cross-reactions with other infectious bacteria common in penetrating wounds. Tests of target-spiked serum and pus extract revealed that RPA is robust to interfering factors and has great potential for further development for biological sample analysis. This method has been confirmed to be reliable for discriminating between toxic and nontoxic C. tetani strains. The RPA assay dramatically improves the diagnostic efficacy with simplified device architecture and is a promising alternative to real-time PCR for tetanus detection.

Tétanos generalizado: Una amenaza persistente, reporte de tres casos y revisión de la literatura / Generalized tetanus: A persistent threat, review of the literature and report of three cases

RESUMEN INTRODUCCIÓN: El tétanos es una enfermedad inmunoprevenible, ocasionada por la bacteria Clostridium tetani, desencadenando una enfermedad caracterizada por espasmos musculares, insuficiencia respiratoria y disautonomías, potencialmente mortal. MATERIALES Y MÉTODOS: Presentamos una serie de tres pacientes que consultaron al servicio de urgencias por presentar trismus, rigidez muscular generalizada y dificultad respiratoria, requiriendo manejo en la unidad de cuidados intensivos, con relajación muscular y administración intramuscular e intratecal de inmunoglobulina antitetánica, con evolución satisfactoria en todos los casos. DISCUSIÓN: Su tratamiento está divido en dos grandes secciones; la primera parte, el control de la infección y eliminación del agente causal, con lavado y desbridamiento de heridas, administración de antibióticos y neutralización de la neurotoxina. La segunda parte del tratamiento está en el soporte vital en la unidad de cuidados intensivos, con la administración de sedación, relajación muscular, control de disautonomías y manejo de complicaciones. CONCLUSIONES: El tétanos a pesar de los avances en vacunación aún es una enfermedad presente, cuyo diagnóstico y tratamiento rápido y adecuado, permite sobrevivir a los pacientes, como en los casos aquí reportados.

ABSTRACT INTRODUCTION: Tetanus is an immuno-preventable disease, produced by the bacterium Clostridium tetani, that causes a disease characterized by muscle spasms, respiratory insufficiency and life-threatening dysautonomia. MATERIALS AND METHODS: We present a series of three patients who consulted for trismus, muscle stiffness and respiratory failure, which required intensive care management, muscle relaxation, intramuscular and intrathecal administration of tetanus immu-noglobulin, with satisfactory outcomes in all the cases. DISCUSSION: Its treatment is divided into two main sections; the first part, the control of infection and elimination of the causative agent, with washing and debridement of wounds, administration of antibiotics and neutralization of the neurotoxin. The second part is life support in the intensive care unit, with the administration of sedation, muscular relaxation and control of dysautonomia and the management of complications. CONCLUSIONS: Despite the advances in vaccination, tetanus is still a present disease, whose diagnosis and rapid and adequate treatment allows patients to survive, as in the cases reported here.

[Tetanus - still a reality in Sweden]. / Stelkramp ännu en realitet i Sverige.

Tetanus (lockjaw) is a potentially life-threatening disease caused by a neurotoxin produced by the spore forming bacterium Clostridium tetani. The incidence has decreased substantially the last decades in most high-income countries, much due to well established vaccination programs. However, although uncommon, tetanus still remains a reality in Sweden. The condition is diagnosed based on clinical parameters and is hard to distinguish from many other more common differential diagnoses. Lack of vaccine induced antibodies is the most important risk factor for developing tetanus. Here we present a patient who developed tetanus two weeks following a puncture wound, but who was initially misdiagnosed with wake-up stroke. The case illustrates the importance of reviewing a patient's tetanus vaccine history, which determines what prophylactic measures are adequate to take, especially following potentially contaminated wounds.

The Role of the Gastrointestinal Tract in Toxigenic Clostridium tetani Infection: A Case-Control Study.

Tetanus arises from wound contamination with Clostridium tetani, but approximately one fifth of patients have no discernable entry wound. Clostridium tetani is culturable from animal feces, suggesting the gastrointestinal tract could be an endogenous reservoir or direct-entry portal, but human data are lacking. In this study of 101 Vietnamese adults with tetanus and 29 hospitalized control subjects, admission stool samples were cultured for C. tetani. Anti-tetanus toxin antibodies were measured by ELISA. Clostridium tetani toxigenicity was evaluated using polymerase chain reaction and sequencing. Toxigenic C. tetani was cultured from stool samples in 50 of 100 (50%) tetanus cases and 12 of 28 (42.9%) control subjects (P = 0.50), and stool samples of 44 of 85 (52.4%) tetanus cases with clinically identified wounds compared with 6 of 15 (47.6%) patients without clinically identified wounds (P = 0.28). Nine of 12 (75%) control subjects with toxigenic C. tetani in their stool samples lacked protective antibody concentrations. These findings fail to show evidence of an association between gastrointestinal C. tetani and tetanus infection, but emphasize the importance of increasing vaccination coverage.

Novel neutralizing human monoclonal antibodies against tetanus neurotoxin.

Tetanus is a fatal disease caused by tetanus neurotoxin (TeNT). TeNT is composed of a light chain (Lc) and a heavy chain, the latter of which is classified into two domains, N-terminus Hn and C-terminus Hc. Several TeNT-neutralizing antibodies have been reported, but it remains unclear which TeNT domains are involved in neutralization. To further understand the mechanism of these antibodies, we isolated TeNT-reactive human antibody clones from peripheral blood mononuclear cells. We then analyzed the reactivity of the isolated antibody clones to each protein domain and their inhibition of Hc-ganglioside GT1b binding, which is critical for TeNT toxicity. We also investigated the TeNT-neutralizing ability of isolated antibody clones and showed that an Hn-reactive clone protected strongly against TeNT toxicity in mice. Furthermore, combination treatment of Hn-reactive antibody clones with both Hc-reactive and TeNT mix (the mixture of Hc, Hn, and Lc proteins)-reactive antibody clones enhanced the neutralizing effect. These results indicated that antibody clones targeting Hn effectively neutralized TeNT. In addition, the use of a cocktail composed of Hc-, Hn-, and TeNT mix-reactive antibodies provided enhanced protection compared to the use of each antibody alone.

The Role of Magnesium in the Management of Acute and Long-Term Symptoms Caused by Tetanus in Two Dogs.

Tetanus in dogs is a relatively uncommon neurological disease caused by the sporogenic bacillus Clostridium tetani. This disease is associated with prolonged hospitalization and mortality rates from 8%-50%. A 2-year-old, neutered male King Charles Spaniel and an approximately 8-months-old female Mongrel dog presented to Companion Animal Clinic with symptoms of muscle rigidity and generalized stiffness. A tentative diagnosis of generalized tetanus was made in both dogs. Treatment consisted of IV fluids, antibiotics (metronidazole), human tetanus antitoxin, analgesics and supportive care. Muscle relaxation was provided by midazolam. Acetylpromazine meleate was added to the treatment of the second dog to better control excitability. Each dog received magnesium therapy on the 10th and 3rd days, respectively; which was provided per os to the first dog and constant rate infusion (4 mg/kg/h) to the second dog. The addition of magnesium helped to increase muscle relaxation and increased the time interval between acetylpromazine administration. On the tenth day, magnesium sulfate was discontinued from the second dog and magnesium aspartate (12 mg/kg), twice a day, per os was administered in both animals. Further muscle relaxation was noted in both dogs with a substantial reduction of tetanus symptoms. Both dogs were discharged from Intensive Care Unit on the 14th and 13th day respectively with sole treatment of magnesium aspartate (12 mg/kg) orally, twice a day. Magnesium aspartate was continued for 14 days and 12 days respectively. Both dogs had progressive reduction of muscle rigidity and the first dog recovered completely. The second dog presented again with muscle rigidity and increased spinal reflexes after the discontinuation of magnesium aspartate, thus therapy with magnesium aspartate was started again and symptoms subsided after the second oral dose of magnesium. Therapy was continued for two more weeks during which muscle rigidity subsided and then was stopped. At that time, tetanus symptoms did not relapse and the dog was considered fully recovered. According to the findings of this case series, magnesium therapy may provide further muscle relaxation during the standard therapeutic protocol of tetanus in dogs. In addition, long term symptoms of the disease were adequately managed with the administration of magnesium aspartate, orally.

Identification of a non-coding RNA and its putative involvement in the regulation of tetanus toxin synthesis in Clostridium tetani.

Clostridium tetani produces the tetanus toxin (TeNT), one of the most powerful bacterial toxins known to humankind and responsible for tetanus. The regulation of toxin expression is complex and involves the alternative sigma factor TetR as well as other regulators. Here, a transcriptional analysis of the TeNT-encoding large plasmid of C. tetani identified a putative non-coding small RNA (sRNA), located in close vicinity of the 3' untranslated region of the tent gene. A northern blot experiment could identify a respective sRNA with a size of approx. 140 nucleotides. Sequence analysis showed that the sRNA contains a 14-nucleotide region that is complementary to a 5' located region of tent. In order to investigate the function of the sRNA, we applied a RNA interference approach targeting the sRNA in two C. tetani wild-type strains; the constructed antisense C. tetani strains showed an approx. threefold increase in both extracellular and total TeNT production compared to the respective wild-type strains. In addition, recombinant C. tetani strains were constructed that contained tent-locus harboring plasmids with and without the sRNA. However, the introduction of the tent-locus without the sRNA in a C. tetani strain lacking the wild-type TeNT-encoding large plasmid resulted in a lower TeNT production compared to the same strain with recombinant tent-locus with the sRNA. This suggests that the expression or the effect of the sRNA is modulated by the C. tetani genetic background, notably that of the wild-type TeNT-encoding large plasmid. In addition, some recombinant strains exhibited modulated growth patterns, characterized by premature bacterial cell lysis. Taken together, our data indicate that the sRNA acts as a negative regulator of TeNT synthesis, with a possible impact on the growth of C. tetani. We hypothesize that the role of this sRNA is to limit toxin levels in the exponential growth phase in order to prevent premature bacterial lysis.

Retrospective anti-tetanus antibody responses of zoo-based Asian elephants (Elephas maximus) and rhinoceros (Rhinocerotidae).

Tetanus toxoids (TT) commercially available for use in horses and livestock are commonly used to vaccinate elephants and rhinoceros that are in human care. Although recommendations for booster intervals have changed in human and horse protocols to reduce the risks associated with hyper-immunity (i.e. B-cell anergy and hypersensitivity reactions) these have generally not been adopted in zoo protocols. Additionally, there is no evidence to demonstrate commercial TT immunogenicity in rhinoceros. In this study, a preliminary analysis of rhinoceros antibody responses to TT was conducted, in addition to an exploration of the impact of various booster frequencies on antibody responses in elephant. Retrospective analysis of archived serum samples was conducted for 9 Asian elephants (Elephas maximus), 7 southern black (Diceros bicornis minor), one southern white (Ceratotherium simum simum), and two greater one-horned (Rhinoceros unicornis) rhinoceros. Pre-vaccination (baseline) samples and those following priming vaccination (rhinoceros only), annual and non-annual boosters were targeted. A commercially available competitive ELISA kit was used to quantify serum anti-TT antibodies. Average baseline and post-vaccination anti-tetanus antibody concentrations were greater in elephant (92 mg/L ± 42, n = 3, N = 3; 125 ± 76, n = 82, N = 9) than in rhinoceros (47 mg/L ± 39, n = 8, N = 8; 44 mg/L ± 37, n = 16, N = 7). Rhinoceros antibody concentrations did not differ markedly following vaccinations from their naturally acquired high pre-vaccination concentrations. Eight elephants demonstrated antibody maintenance for 3-5 years without a tetanus booster. Additionally, although five out of nine elephants developed local reactions consistent with delayed type IV hypersensitivity following some boosters, there was no association between high antibody concentrations and increased incidence of adverse reactions. In addition, no decrease in antibody concentrations was detected as a result of annual vaccination in elephants, though this does not entirely rule out potential for B-cell anergy.

Does tetanus vaccination contribute to reduced severity of the COVID-19 infection?

We present the hypothesis to the scientific community actively designing clinical trials and recommending public health guidelines to control the pandemic that - "Tetanus vaccination may be contributing to reduced severity of the COVID-19 infection" - and urge further research to validate or invalidate the effectiveness of the tetanus toxoid vaccine against COVID-19. This hypothesis was revealed by an explainable artificial intelligence system unleashed on open public biomedical datasets. As a foundation for scientific rigor, we describe the data and the artificial intelligence system, document the provenance and methodology used to derive the hypothesis and also gather potentially relevant data/evidence from recent studies. We conclude that while correlations may not be reason for causation, correlations from multiple sources is more than a serendipitous coincidence that is worthy of further and deeper investigation.

Tetanus vaccine-induced human neutralizing antibodies provide full protection against neurotoxin challenge in mice.

Clostridium tetani causes life-threatening disease by producing tetanus neurotoxin (TeNT), one of the most toxic protein substances. Toxicosis can be prevented and cured by administration of anti-TeNT neutralizing antibodies. Here, we identified a series of monoclonal antibodies (mAbs) derived from memory B cells of a healthy adult immunized with the C-terminal domain of TeNT (TeNT-Hc). Thirteen mAbs bound to both tetanus toxoid (TT) and TeNT-Hc, while two mAbs recognized only TT. VH3-23 was the most frequently used germline gene in these TT-binding mAbs, and the pairwise identity values of the VH gene sequences ranged from 27% to 69%. Three of these mAbs-T3, T7, and T9-6-completely protected mice from challenge with 2× LD50 of TeNT, and two (T2 and T18) significantly prolonged the survival time. The five neutralizing mAbs recognized distinct epitopes on TT, with binding affinities ranging from 0.123 to 11.9 nM. Our study provides promising therapeutic candidates for tetanus.

Tétanos generalizado en adulto. Reporte de caso / Adult generalized tetanus. Case report

RESUMEN Fundamento: El tétanos es una enfermedad infecciosa causada por las esporas de la bacteria Clostridium tetani que afecta el sistema nervioso. La inmunización contra esta enfermedad ha permitido reducir la morbilidad y la mortalidad en Cuba por esa causa. Los pocos casos reportados son pacientes sin previa vacunación contra el tétanos, por lo que constituye de interés para la comunidad científica el reporte de aquellos que desarrollan esa enfermedad después de haber sido vacunados. Objetivo: Describir el caso de un paciente con diagnóstico de tétanos generalizado a pesar de que ya había sido vacunado contra esa enfermedad. Presentación del caso: Paciente de 33 años, con el antecedente de haber sido vacunado contra el tétanos, al cual le diagnosticaron tétanos generalizado, por lo se decidió su ingresó en la unidad de cuidados intensivos. Clínicamente se manifestó por contracciones musculares generalizadas y rigidez, los síntomas y signos neurológicos tuvieron una duración de 4 semanas. A pesar de las complicaciones el paciente egresó con adecuada calidad de vida. Conclusiones: La presentación de este caso busca concientizar en la comunidad científica la importancia de considerar el diagnóstico de tétanos en pacientes ya vacunados, lo cual es poco frecuente y obliga a actuar con prontitud.

ABSTRACT Background: Tetanus is an infectious disease caused by the bacterium Clostridium tetani spores which affects the nervous system. In Cuba, immunization against this disease has made it possible to reduce morbidity and mortality from this cause. The few cases reported are patients without prior vaccination against tetanus, so is the interest to the scientific community the reporting of those who develop this disease after having been vaccinated. Objective: To describe a patient´s case with a generalized tetanus diagnosis despite has already been vaccinated against this disease. Case report: A 33-year-old patient, with a history of has been vaccinated against tetanus, and diagnosed with generalized tetanus, so it was decided he to be admitted to the intensive care unit. Clinically manifested by generalized muscle contractions and stiffness, the neurological symptoms and signs lasted 4 weeks. Despite the complications, the patient discharged from hospital with an adequate life quality. Conclusions: This case presentation searches for raising awareness in the scientific community about the importance of considering the diagnosis of tetanus in previous vaccinated patients, which is rare and requires quickness of action.

Time-course transcriptomics reveals that amino acids catabolism plays a key role in toxinogenesis and morphology in Clostridium tetani.

Tetanus is a fatal disease caused by Clostridium tetani infections. To prevent infections, a toxoid vaccine, developed almost a century ago, is routinely used in humans and animals. The vaccine is listed in the World Health Organisation list of Essential Medicines and can be produced and administered very cheaply in the developing world for less than one US Dollar per dose. Recent developments in both analytical tools and frameworks for systems biology provide industry with an opportunity to gain a deeper understanding of the parameters that determine C. tetani virulence and physiological behaviour in bioreactors. Here, we compared a traditional fermentation process with a fermentation medium supplemented with five heavily consumed amino acids. The experiment demonstrated that amino acid catabolism plays a key role in the virulence of C. tetani. The addition of the five amino acids favoured growth, decreased toxin production and changed C. tetani morphology. Using time-course transcriptomics, we created a "fermentation map", which shows that the tetanus toxin transcriptional regulator BotR, P21 and the tetanus toxin gene was downregulated. Moreover, this in-depth analysis revealed potential genes that might be involved in C. tetani virulence regulation. We observed differential expression of genes related to cell separation, surface/cell adhesion, pyrimidine biosynthesis and salvage, flagellar motility, and prophage genes. Overall, the fermentation map shows that, mediated by free amino acid concentrations, virulence in C. tetani is regulated at the transcriptional level and affects a plethora of metabolic functions.