Development and characterization of a novel neutralizing scFv vectored immunoprophylaxis against botulinum toxin type A

Botulinum toxin is a protein toxin secreted by Clostridium botulinum that is strongly neurotoxic. Due to its characteristics of being super toxic, quick acting, and difficult to prevent, the currently reported antiviral studies focusing on monoclonal antibodies have limited effectiveness. Therefore, for the sake of effectively prevention and treatment of botulism and to maintain country biosecurity as well as the health of the population, in this study, we intend to establish a single chain antibody (scFv) targeting the carboxyl terminal binding functional domain of the botulinum neurotoxin heavy chain (BONT/AHc) of botulinum neurotoxin type A, and explore the value of a new passive immune method in antiviral research which based on adeno-associated virus (AAV) mediated vector immunoprophylaxis (VIP) strategy. The scFv small-molecular single-chain antibody sequenced, designed, constructed, expressed and purified by hybridoma has high neutralising activity and affinity level, which can lay a good foundation for the modification and development of antibody engineering drugs. In vivo experiments, AAV-mediated scFv engineering drug has good anti-BONT/A toxin neutralisation ability, has advantages of simple operation, stable expression and good efficacy, and may be one of the effective treatment strategies for long-term prevention and protection of BONT/A botulinum neurotoxin.

Iatrogenic botulism cases after gastric and axillary application of botulinum toxin and review of literature

INTRODUCTION

Iatrogenic botulism is a rare, serious disease that progresses with descending paralysis and develops after cosmetic or therapeutic botulinum toxin-A (BoNT-A) application.

CASE PRESENTATIONS

In this case series; six cases of iatrogenic botulism followed up in our center are presented. Four of these developed after gastric BoNT-A and two after axillary BoNT-A application.

RESULTS

The most important cause for the disease was the use of unlicensed products and high-dose toxin applications. The first symptoms were blurred vision, double vision, difficulty in swallowing, and hoarseness. Symptoms appeared within 4-10 days after the application of BoNT-A. Symptoms progressed in the course of descending paralysis in the following days with fatigue, weakness in extremities and respiratory distress. Diagnosis was based on patient history and clinical findings. The main principles of foodborne botulism therapy were applied in the treatment of iatrogenic botulism. If clinical worsening continued, regardless of the time elapsed after BoNT-A application, the use of botulinum antitoxin made a significant contribution to clinical improvement and was recommended.

CONCLUSIONS

Routine and new indications for BoNT-A usage are increasing and, as a result, cases of iatrogenic botulism will be encountered more frequently. Physicians should be alert for iatrogenic botulism in the follow-up after BoNT-A applications and in the differential diagnosis of neurological diseases that are presented with similar findings.

Standardization of the Japanese National Standard, Equine Botulinum Antitoxin Type A, and Factors Affecting Standardization

Equine botulinum antitoxin is one of the most popular countermeasures for human botulism. The unitage of the antitoxin product is defined according to national minimum requirement or pharmacopoeia in each country by referring to national standard antitoxins for four types (A, B, E, and F). With the expected depletion of the national standard antitoxins, replacement national standard antitoxins are produced and standardized through collaboration of the National Control Laboratory and other participants, including manufacturer(s). Therefore, Japanese National Standard Botulinum Antitoxin Type A, Equine, was replaced according to the results of a collaborative study involving the National Institute of Infectious Diseases and KM Biologics Co., Ltd. The unitage of the replacement material was determined through mouse neutralization tests, which involved toxin-antitoxin mixture injection at pH 7.0. Potency value of 440 units/vial was obtained. However, the Japanese Minimum Requirement for Biological Products was revised, and the neutralization reactions were repeated at pH 6.0, for which considerably different potency value (656 units/vial) and survival profile of mice were obtained. In September 2021, the replacement material, Japanese National Standard Botulinum Antitoxin Type A, Equine, lot 2, was established with potency value of 656 Units/vial. The impact of pH-dependent change in potency on antitoxin quality control is discussed.

Aminopyridines Restore Ventilation and Reverse Respiratory Acidosis at Late Stages of Botulism in Mice

Botulinum neurotoxin (BoNT) is a potent protein toxin that causes muscle paralysis and death by asphyxiation. Treatments for symptomatic botulism are intubation and supportive care until respiratory function recovers. Aminopyridines have recently emerged as potential treatments for botulism. The clinically approved drug 3,4-diaminopyridine (3,4-DAP) rapidly reverses toxic signs of botulism and has antidotal effects when continuously administered in rodent models of lethal botulism. Although the therapeutic effects of 3,4-DAP likely result from the reversal of diaphragm paralysis, the corresponding effects on respiratory physiology are not understood. Here, we combined unrestrained whole-body plethysmography (UWBP) with arterial blood gas measurements to study the effects of 3,4-DAP, and other aminopyridines, on ventilation and respiration at terminal stages of botulism in mice. Treatment with clinically relevant doses of 3,4-DAP restored ventilation in a dose-dependent manner, producing significant improvements in ventilatory parameters within 10 minutes. Concomitant with improved ventilation, 3,4-DAP treatment reversed botulism-induced respiratory acidosis, restoring blood levels of CO2, pH, and lactate to normal physiologic levels. Having established that 3,4-DAP-mediated improvements in ventilation were directly correlated with improved respiration, we used UWBP to quantitatively evaluate nine additional aminopyridines in BoNT/A-intoxicated mice. Multiple aminopyridines were identified with comparable or enhanced therapeutic efficacies compared with 3,4-DAP, including aminopyridines that selectively improved tidal volume versus respiratory rate and vice versa. In addition to contributing to a growing body of evidence supporting the use of aminopyridines to treat clinical botulism, these data lay the groundwork for the development of aminopyridine derivatives with improved pharmacological properties. SIGNIFICANCE STATEMENT: There is a critical need for fast-acting treatments to reverse respiratory paralysis in patients with botulism. This study used unrestrained, whole-body plethysmography and arterial blood gas analysis to show that aminopyridines rapidly restore ventilation and respiration and reverse respiratory acidosis when administered to mice at terminal stages of botulism. In addition to supporting the use of aminopyridines as first-line treatments for botulism symptoms, these data are expected to contribute to the development of new aminopyridine derivatives with improved pharmacological properties.

Treating rosacea with botulism toxin: Protocol for a systematic review and meta-analysis

BACKGROUND

Rosacea is a chronic inflammatory disease usually associated with persistent erythema and periodic flushing. This disease is difficult to treat, and the outcomes are often unsatisfactory and prone to recurrence. In recent years, botulinum toxin has been used as a new treatment for rosacea; however, its efficacy and safety remain under discussion. Although a systematic review of the effectiveness and safety of botulinum toxin has been previously conducted by other researchers, our systematic review and meta-analysis evaluate the efficacy of botulinum toxin from a more comprehensive and detailed perspective to provide evidence for clinicians.

METHODS

Any study using botulinum toxin for the treatment of rosacea was considered for the analysis.

RESULTS

A total of 22 studies were included, 9 of which were randomized controlled trials involving 720 subjects. After treatment, all studies showed varying degrees of improvement in patient signs and symptoms along with reduced Clinician's Erythema Assessment (CEA) scores. The improvement was maintained for several months, and the adverse effects were mild and self-limiting.

CONCLUSION

Botulinum toxin may be an effective treatment for patients with rosacea; however, further clinical evidence is needed to confirm its long-term efficacy and side effects. The study was preregistered with Prospero (CRD42022358911).

Efficacy and Safety Analysis of Botox Application and Iatrogenic Botulism: Panacea or Peril?

Clostridium botulinum toxin-A (BoNT-A) creates temporary paralysis in the muscles by acting on the muscle-nerve junction. It is injected into the mimic muscles when a decrease in the movements of the mimic muscles is desired. Despite many favorable applications, the use of BoNT-A is not without drawbacks. Although there is no expected serious side effect on health in BoNT-A treatments, various problems can be encountered in patients treated for aesthetic purposes. Botulism is a rare but potentially life-threatening syndrome, which is caused by the toxin produced by the bacterium Clostridium botulinum, which acts on the nervous system, vegetative forms of C. botulinum can only survive in anaerobic conditions, while spore forms are common in nature and can withstand harsh conditions. Botulism can stem from bacterial spores which release toxin in the body; in the form of enteric botulism, and wound botulism. The cases that develop 'iatrogenic botulism' after such procedures are usually those receiving high-dose toxin for therapeutic purposes. The treatment of botulism mainly consists of anti-toxin therapy and, if necessary, intensive care to prevent organ failures, including respiratory support. This article aims to cover all these issues related to botulism and other adverse outcomes related to BoNT-A injection in light of the most recent literature.

Iatrogenic systemic botulism after intragastric botulinum neurotoxin injection: Case report

BACKGROUND AND PURPOSE

The recent off-label use of botulinum neurotoxin (BoNT) for intragastric obesity treatment has led to 67 cases of systemic botulism in Türkiye, Germany, Austria and Switzerland. This case report highlights the potential risks and adverse effects associated with this treatment.

CASE REPORT

A 36-year-old female presented to the emergency room with shortness of breath, fatigue, difficulty in eating and holding her head, constipation and double vision after receiving intragastric BoNT injection for obesity treatment. She had bilateral orbicularis oculi weakness, facial diplegia, weak tongue, masseter, neck and extremity muscles. Electromyography showed a presynaptic type neuromuscular junction disorder. The patient was admitted to the intensive care unit and administered botulinum heptavalent equine-derived antitoxin, but the medication had to be stopped due to a reaction. The patient was started on pyridostigmine for symptomatic treatment and was transferred to an inpatient clinic after minimal improvement. She was discharged after 7 days of follow-up.

CONCLUSION

Clinicians should be cautious of the potential risks of intragastric BoNT injection for obesity treatment and consider systemic botulism as a potential adverse effect. Antitoxin treatment should be considered in clinically progressing patients despite negative botulinum toxin testing.

Duration of Fecal Excretion of Clostridium Botulinum and Botulinum Neurotoxin in Patients Recovering from Infant Botulism

This study sought to determine duration of fecal excretion of Clostridium botulinum organisms and neurotoxin after onset of infant botulism in 66 affected infants. Median excretion was longer for type A than type B patients (organisms: 5.9 vs 3.5 weeks, toxin: 4.8 vs 1.6 weeks, respectively). Toxin excretion always ceased before organism excretion. Antibiotic therapy did not affect duration of excretion.

Iatrogenic Botulism: A Case Treated With Botulinum Antitoxin

OBJECTIVE

Botulinum toxin type A is widely used for the treatment of spasticity, focal dystonia, hemifacial spasm, hyperhidrosis, strabismus, chronic migraine, and also cosmetic purposes. Therapeutic use is commonly effective and safe. However, if toxin enters the vascular space and gets through to peripheral cholinergic nerve terminals, it may lead to iatrogenic botulism.

METHOD

We presented a patient who is diagnosed as iatrogenic botulism and treated with antitoxin at the 15th day of the exposure.

RESULTS

After the antitoxin administration, dramatical response to the treatment was observed.

CONCLUSIONS

In this report, we want to evaluate a new case of iatrogenic botulism and emphasize the importance of antitoxin administration regardless the timing of the exposure for patients with progressing paralysis.

Botulism in Spain: Epidemiology and Outcomes of Antitoxin Treatment, 1997-2019

BACKGROUND

Botulism is a low incidence but potentially fatal infectious disease caused by neurotoxins produced mainly by Clostridium botulinum. There are different routes of acquisition, food-borne and infant/intestinal being the most frequent presentation, and antitoxin is the treatment of choice in all cases. In Spain, botulism is under surveillance, and case reporting is mandatory.

METHODS

This retrospective study attempts to provide a more complete picture of the epidemiology of botulism in Spain from 1997 to 2019 and an assessment of the treatment, including the relationship between a delay in antitoxin administration and the length of hospitalization using the Cox proportional hazards test and Kruskal-Wallis test, and an approach to the frequency of adverse events, issues for which no previous national data have been published.

RESULTS

Eight of the 44 outbreaks were associated with contaminated commercial foods involving ≤7 cases/outbreak; preserved vegetables were the main source of infection, followed by fish products; early antitoxin administration significantly reduces the hospital stay, and adverse reactions to the antitoxin affect around 3% of treated cases.

Investigation of Salicylanilides as Botulinum Toxin Antagonists

Botulinum neurotoxin serotype A (BoNT/A) is recognized by the Centers for Disease Control and Prevention (CDC) as the most potent toxin and as a Tier 1 biowarfare agent. The severity and longevity of botulism stemming from BoNT/A is of significant therapeutic concern, and early administration of antitoxin-antibody therapy is the only approved pharmaceutical treatment for botulism. Small molecule therapeutic strategies have targeted both the heavy chain (HC) and the light chain (LC) catalytic active site and α-/β-exosites. The LC translocation mechanism has also been studied, but an effective, nontoxic inhibitor remains underexplored. In this work, we screened a library of salicylanilides as potential translocation inhibitors. Potential leads following a primary screen were further scrutinized to identify sal30, which has a cellular minimal concentration of a drug that is required for 50% inhibition (IC50) value of 141 nM. The inquiry of salicylanilide sal30's mechanism of action was explored through a self-quenched fluorogenic substrate conjugated to bovine serum albumin (DQ-BSA) fluorescence, confocal microscopy, and vacuolar H+-ATPase (V-ATPase) inhibition assays. The summation of these findings imply that endolysosomal proton translocation through the protonophore mechanism of sal30 causes endosome pH to increase, which in turn prevents LC translocation into cytosol, a process that requires an acidic pH. Thus, the inhibition of BoNT/A activity by salicylanilides likely occurs through disruption of pH-dependent endosomal LC translocation. We further probed BoNT inhibition by sal30 using additivity analysis studies with bafilomycin A1, a known BoNT/A LC translocation inhibitor, which indicated the absence of synergy between the two ionophores.

Antidotal treatment of botulism in rats by continuous infusion with 3,4-diaminopyridine

Botulinum neurotoxins (BoNTs) are highly potent, select agent toxins that inhibit neurotransmitter release at motor nerve terminals, causing muscle paralysis and death by asphyxiation. Other than post-exposure prophylaxis with antitoxin, the only treatment option for symptomatic botulism is intubation and supportive care until recovery, which can require weeks or longer. In previous studies, we reported the FDA-approved drug 3,4-diaminopyridine (3,4-DAP) reverses early botulism symptoms and prolongs survival in lethally intoxicated mice. However, the symptomatic benefits of 3,4-DAP are limited by its rapid clearance. Here we investigated whether 3,4-DAP could sustain symptomatic benefits throughout the full course of respiratory paralysis in lethally intoxicated rats. First, we confirmed serial injections of 3,4-DAP stabilized toxic signs and prolonged survival in rats challenged with 2.5 LD50 BoNT/A. Rebound of toxic signs and death occurred within hours after the final 3,4-DAP treatment, consistent with the short half-life of 3,4-DAP in rats. Based on these data, we next investigated whether the therapeutic benefits of 3,4-DAP could be sustained throughout the course of botulism by continuous infusion. To ensure administration of 3,4-DAP at clinically relevant doses, three infusion dose rates (0.5, 1.0 and 1.5 mg/kg∙h) were identified that produced steady-state serum levels of 3,4-DAP consistent with clinical dosing. We then compared dose-dependent effects of 3,4-DAP on toxic signs and survival in rats intoxicated with 2.5 LD50 BoNT/A. In contrast to saline vehicle, which resulted in 100% mortality, infusion of 3,4-DAP at ≥ 1.0 mg/kg∙h from 1 to 14 d after intoxication produced 94.4% survival and full resolution of toxic signs, without rebound of toxic signs after infusion was stopped. In contrast, withdrawal of 3,4-DAP infusion at 5 d resulted in re-emergence of toxic sign and death within 12 h, confirming antidotal outcomes require sustained 3,4-DAP treatment for longer than 5 d after intoxication. We exploited this novel survival model of lethal botulism to explore neurophysiological parameters of diaphragm paralysis and recovery. While neurotransmission was nearly eliminated at 5 d, neurotransmission was significantly improved at 21 d in 3,4-DAP-infused survivors, although still depressed compared to naïve rats. 3,4-DAP is the first small molecule to reverse systemic paralysis and promote survival in animal models of botulism, thereby meeting a critical treatment need that is not addressed by post-exposure prophylaxis with conventional antitoxin. These data contribute to a growing body of evidence supporting the use of 3,4-DAP to treat clinical botulism.

[Iatrogenic botulism in therapeutic use of botulinum toxin]

The review summarises the current knowledge of the treatment of iatrogenic botulinum toxin overdose. The symptoms may be diffuse, and suspicion should be raised based on time of symptom appearance relative to the time of exposure. Iatrogenic botulism may appear if the maximum recommended total dose of botulinum toxin has been exceeded and if the drug is spread locally from the site of injection or is redistributed to the systemic circulation. The adverse drug reactions frequency is possibly underreported. Fast initiation of the available antidote may be needed. The guideline provided on treatment of iatrogenic botulism is developed from non-iatrogenic botulism.

Outbreak of foodborne botulism in Alexandria, Egypt: modulating indications for administration of heptavalent botulinum antitoxin

In October 2019, ninety-four patients were admitted into Alexandria Poison Center (APC) with a history of ingestion of Feseekh (salted fish). In an attempt to allocate the resources, not all patients were given HBAT (botulism antitoxin heptavalent (A, B, C, D, E, F, G) equine immediately. The current study aimed to portray the clinical characteristics of the cases, explore the possible relation between these characteristics and necessity of HBAT administration, explore the reliability of mouse lethal test, and establish a clinical guide for management including preservation of resources. The current prospective study included 94 patients who were admitted to Alexandria Poison Center (APC) in the period from the 29^th of September to the 27^th of October 2019. The patients' data were recorded using a checklist that includes: personal data, past medical history, clinical assessment, investigations, treatment, and the outcome. The checklist was carried out to assess and follow up each patient. Hospitalized patients were categorized according to symptoms consistent with botulism. The equine HBAT, made by Emergent BioSolutions Canada Inc. (formerly Cangene Corporation), was used in the treatment. HBAT was given to thirty-four patients (36.2%) only out of the total admission. However, eighty-two (87.2%) of patients were completely cured, whereas ten patients (10.6%) were discharged with mild neurological sequels and death occurred only in two cases (2.2%). Sixty cases (63.8%) with suspected foodborne botulism could be managed by supportive treatment only with no need for HBAT, while patients with evident neurological signs received HBAT immediately.

A Rabbit Model for the Evaluation of Drugs for Treating the Chronic Phase of Botulism

Antitoxin, the only licensed drug therapy for botulism, neutralizes circulating botulinum neurotoxin (BoNT). However, antitoxin is no longer effective when a critical amount of BoNT has already entered its target nerve cells. The outcome is a chronic phase of botulism that is characterized by prolonged paralysis. In this stage, blocking toxin activity within cells by next-generation intraneuronal anti-botulinum drugs (INABDs) may shorten the chronic phase of the disease and accelerate recovery. However, there is a lack of adequate animal models that simulate the chronic phase of botulism for evaluating the efficacy of INABDs. Herein, we report the development of a rabbit model for the chronic phase of botulism, induced by intoxication with a sublethal dose of BoNT. Spirometry monitoring enabled us to detect deviations from normal respiration and to quantitatively define the time to symptom onset and disease duration. A 0.85 rabbit intramuscular median lethal dose of BoNT/A elicited the most consistent and prolonged disease duration (mean = 11.8 days, relative standard deviation = 27.9%) that still enabled spontaneous recovery. Post-exposure treatment with antitoxin at various time points significantly shortened the disease duration, providing a proof of concept that the new model is adequate for evaluating novel therapeutics for botulism.

Safety verification for polysorbate 20, pharmaceutical excipient for intramuscular administration, in Sprague-Dawley rats and New Zealand White rabbits

Human serum albumin (HSA) has been widely used as a pharmaceutical excipient in Botulinum toxin serotype A (BoNT/A) products that are indicated for use in therapeutics and cosmetics. However, HSA as a human-derived material has some concerns, such as the potential risk of transmission of infectious agents, an insufficient supply, and difficulty in maintaining a certain quality. For those reasons, newly developed BoNT/A products (CORETOX^®, Medytox, Inc., Republic of Korea) contained polysorbate 20, a non-human-derived excipient, to replace the HSA. However, most safety studies of polysorbate 20 have been conducted with non-invasive routes of administration, and thus there are a few studies on the safety of polysorbate 20 when administered intramuscularly. To secure the in vivo safety profile of polysorbate 20, a four-week repeated intramuscular dose toxicity study (0.02, 0.1, and 0.4 mg/kg, one injection every two weeks for a total of three injections) was conducted in 66 Sprague-Dawley (SD) rats. An intradermal irritation study was further conducted with 18 New Zealand White (NZW) rabbits. The toxicological evaluation of HSA (0.06 and 0.12 mg/kg) was also carried out as a comparative substance. Systemic and local toxicities were not observed in any of the SD rats or NZW rabbits based on clinical signs, body weight, hematology, clinical biochemistry, macroscopic findings on necropsy, histopathology of the injection site, and allergic reactions. The current study suggested that intramuscular administration of polysorbate 20 was considered to be safe at a level similar to that of HSA, which has an in vivo safety profile accumulated over the years. This provided the basis for the in vivo safety profile of polysorbate 20 administered intramuscularly and the scientific reliability of the use of polysorbate 20 as an alternative to HSA, which is used as an excipient for various pharmaceuticals in terms of its safety.

Neuronal delivery of antibodies has therapeutic effects in animal models of botulism

Botulism is caused by a potent neurotoxin that blocks neuromuscular transmission, resulting in death by asphyxiation. Currently, the therapeutic options are limited and there is no antidote. Here, we harness the structural and trafficking properties of an atoxic derivative of botulinum neurotoxin (BoNT) to transport a function-blocking single-domain antibody into the neuronal cytosol where it can inhibit BoNT serotype A (BoNT/A1) molecular toxicity. Post-symptomatic treatment relieved toxic signs of botulism and rescued mice, guinea pigs, and nonhuman primates after lethal BoNT/A1 challenge. These data demonstrate that atoxic BoNT derivatives can be harnessed to deliver therapeutic protein moieties to the neuronal cytoplasm where they bind and neutralize intracellular targets in experimental models. The generalizability of this platform might enable delivery of antibodies and other protein-based therapeutics to previously inaccessible intraneuronal targets.

Two Cases of Infant Botulism Presenting with Altered Mental Status

Infant botulism is a progressive process described as starting with descending weakness, facial palsies and constipation. Loss of bulbar reflexes and flaccid paralysis are common in infants less than 6 months old who have infant botulism. Clostridium botulinum, the bacteria that produce the toxin that causes this condition, are ubiquitous in the United States including Hawai'i, but infant botulism is rarely reported here. This report describes 2 cases of infant botulism with atypical initial presentations diagnosed on O'ahu, Hawai'i. Patient A is a 3-month-old male who presented with altered mental status, including inconsolability, who progressed to loss of gag reflex and constipation. Due to early concern for meningitis, Patient A was treated with antibiotics, however further evaluation led to eventual positive testing for botulinum B toxin. Patient B is a 2-month-old female who presented with somnolence and fever after immunizations and progressed to respiratory failure and apparent dehydration. Because she presented shortly after receiving immunizations, metabolic disorders were strongly considered as a potential cause of symptoms, but Patient B had normal metabolic evaluation and eventually tested positive for botulinum A toxin. Altered mental status and fever are unusual presentations for infant botulism. Infant botulism should be considered in infants with altered mental status when the course of illness includes the development of constipation and weakness, and evaluations are not suggestive of alternative causes, including infection, metabolic diseases, and spinal muscular atrophy. Early consideration and treatment of infant botulism should be considered for infants presenting with altered mental status who develop neuromuscular weakness. The Infant Botulism Treatment and Prevention Program (www.infantbotulism.org) should be contacted early for assistance with diagnosis and treatment.

Lambert-Eaton Myasthenic Syndrome, Botulism, and Immune Checkpoint Inhibitor-Related Myasthenia Gravis

PURPOSE OF REVIEW

This article reviews the pathophysiology, epidemiology, clinical presentation, diagnosis, and treatment of Lambert-Eaton myasthenic syndrome (LEMS) and of botulism, and immune-related myasthenia gravis (MG) occurring in the context of immune checkpoint inhibitor therapy for cancer.

RECENT FINDINGS

The suspicion that LEMS is rare but also likely underdiagnosed is supported by recent epidemiologic data. A validated, LEMS-specific scale now exists to assess and monitor disease, and symptomatic and immunomodulatory treatments are available. As presynaptic disorders of neuromuscular transmission, LEMS and botulism share electrodiagnostic abnormalities but have important distinguishing features. Knowledge of the clinical features of botulism is needed, particularly with continued cases of infant botulism, the opioid epidemic increasing the incidence of wound botulism, and medical use of botulinum toxin, which may cause iatrogenic botulism. Foodborne botulism remains rare. Prompt recognition of botulism and administration of antitoxin can improve outcomes. MG may be exacerbated or may present de novo in the context of immune activation from immune checkpoint inhibitor therapies for cancer. Immune-related MG commonly overlaps with myositis and myocarditis. Corticosteroids typically result in improvement. However, immune-related MG can be more fulminant than its idiopathic counterpart and may cause permanent disability or death.

SUMMARY

The diagnosis of LEMS, botulism, or immune-related MG can generally be made from the patient's history, supplemented with directed questions, a physical examination designed to demonstrate abnormalities, and laboratory and electrodiagnostic testing. Early diagnosis and carefully selected treatment not only improve outcomes of the neuromuscular disease but can affect the prognosis of underlying malignancy, when present.

Symptomatic treatment of botulism with a clinically approved small molecule

Botulinum neurotoxins (BoNTs) are potent neuroparalytic toxins that cause mortality through respiratory paralysis. The approved medical countermeasure for BoNT poisoning is infusion of antitoxin immunoglobulins. However, antitoxins have poor therapeutic efficacy in symptomatic patients; thus, there is an urgent need for treatments that reduce the need for artificial ventilation. We report that the US Food and Drug Administration-approved potassium channel blocker 3,4-diaminopyridine (3,4-DAP) reverses respiratory depression and neuromuscular weakness in murine models of acute and chronic botulism. In ex vivo studies, 3,4-DAP restored end-plate potentials and twitch contractions of diaphragms isolated from mice at terminal stages of BoNT serotype A (BoNT/A) botulism. In vivo, human-equivalent doses of 3,4-DAP reversed signs of severe respiratory depression and restored mobility in BoNT/A-intoxicated mice at terminal stages of respiratory collapse. Multiple-dosing administration of 3,4-DAP improved respiration and extended survival at up to 5 LD50 BoNT/A. Finally, 3,4-DAP reduced gastrocnemius muscle paralysis and reversed respiratory depression in sublethal models of serotype A-, B-, and E-induced botulism. These findings make a compelling argument for repurposing 3,4-DAP to symptomatically treat symptoms of muscle paralysis caused by botulism, independent of serotype. Furthermore, they suggest that 3,4-DAP is effective for a range of botulism symptoms at clinically relevant time points.

Cost savings associated with timely treatment of botulism with botulism antitoxin heptavalent product

Background

Botulism is a rare, serious, and sometimes fatal paralytic illness caused by exposure to neurotoxins produced by Clostridium botulinum bacteria. Patients with documented or suspected exposure to botulinum toxin serotypes A-G can be treated with BAT^® [Botulism Antitoxin Heptavalent (A, B, C, D, E, F, G)–(Equine)] product, which was approved in 2013 in the United States (US). Patients with botulism have demonstrated greater clinical benefit with early BAT product treatment (≤2 days from symptom onset) versus late treatment (>2 days).

Objective

Economic outcomes associated with improved clinical outcome benefits of BAT product treatment have not yet been reported. This ad hoc analysis aimed to estimate and compare costs associated with hospitalization, intensive care unit stay, and mechanical ventilation for patients with botulism administered BAT product treatment early or late.

Methods

Clinical outcomes data for early and late BAT product treatment were obtained from a patient registry conducted between October 2014 and July 2017. Total per patient mean daily costs were estimated based on information from published literature. Total population costs per group were calculated by multiplying estimated mean cost per patient by the average annual number of non-infant botulism cases in the US.

Results

Mean per patient costs were 2.5 times lower for patients treated with BAT product early versus late. On average in the US, early BAT product treatment could save greater than $3.9 million per year versus late treatment.

Conclusion

Substantial economic savings can be achieved with early BAT product treatment. The findings support the recommendation for public health authorities to ensure antitoxin treatment is readily available in sufficient quantities to manage botulism cases, including sporadic outbreaks and potential mass exposure biological attacks.

Efficacy of equine botulism antitoxin in botulism poisoning in a guinea pig model

Background

Botulism is a disease caused by neurogenic toxins that block acetylcholine release, resulting in potentially life threatening neuroparalysis. Seven distinct serotypes of botulinum neurotoxins (BoNTs) have been described and are found in nature world-wide. This, combined with ease of production, make BoNTs a significant bioweapon threat. An essential countermeasure to this threat is an antitoxin to remove circulating toxin. An antitoxin, tradename BAT (Botulism Antitoxin Heptavalent (A, B, C, D, E, F, G)–(Equine)), has been developed and its efficacy evaluated against all seven serotypes in guinea pigs.

Methods and findings

Studies were conducted to establish the lethal dose and clinical course of intoxication for all seven toxins, and post-exposure prophylactic efficacy of BAT product. Animals were monitored for signs of intoxication and mortality for 14 days. Guinea pig intramuscular LD_50s (GPIMLD₅₀) for all BoNTs ranged from 2.0 (serotype C) to 73.2 (serotype E) of mouse intraperitoneal LD₅₀ units. A dose of 4x GPIMLD₅₀ was identified as the appropriate toxin dose for use in subsequent efficacy and post-exposure prophylaxis studies. The main clinical signs observed included hind limb paralysis, weak limb, change in breathing rate/pattern, and forced abdominal respiration. Mean time to onset of clinical signs ranged from 12 hours (serotype E) to 39 hours (serotype G). Twelve hours post-intoxication was selected as the appropriate time point for intervention for all serotypes apart from E where 6 hours was selected because of the rapid onset and progression of clinical signs. Post-exposure treatment with BAT product resulted in a significantly (p<0.0001) higher survival at >0.008 scaled human dose for serotypes A, B, C, F and G, at >0.2x for serotype D and >0.04x for serotype E.

Conclusions

These studies confirm the efficacy of BAT as a post-exposure prophylactic therapy against all seven known BoNT serotypes.

Botulism - a rare but still present, life-threatening disease

Botulism caused by toxins of Clostridium botulinum and other neurotoxic clostridia is a rare but life-threatening disease with neurological symptoms. Food-borne botulism (food poisoning) is the most common type worldwide; rarely, wound botulism, infant botulism, or botulism of unknown etiology may also occur. Botulism is a very rare disease in the Czech Republic as well, with only nine cases reported since 2008 (EPIDAT). These were mostly sporadic cases of food-borne botulism except a small family outbreak with three cases due to the consumption of homemade pork pate (2013). This outbreak prompted the creation of a national standby supply of life-saving anti-infective drugs in Prague. This article reviews the etiology, epidemiology, clinical manifestations, diagnosis, and therapy of botulism.

[Foodbourne Botulism: A Forgotten Disease]

Botulism is a serious illness caused by exposure to botulinum toxin. It is manifested by flaccid, paralysis, symmetric and in descending pattern affecting cranial and peripheral nerves. Given the frequent need for invasive mechanical ventilation, these patients should be approached in an intensive care setting. Treatment with anti-botulinum toxin is the only effective treatment. The authors present the case of a 64-year-old patient, with vomiting and vertigo, evolution to diplopia, dysphagia and flaccid, muscle paralysis, installation after ingestion of canning homemade. From the etiologica, we highlight the electroneuromyogram study with a pre-synaptic lesion compatible with the botulism hypothesis. Progressive improvement of the deficits after administration of anti-botulinum toxin. A brief theoretical review is made of a serious, potentially fatal and infrequent pathology in our country.

[Toxin-infections and toxin-related diseases due to Clostridia other than Clostridium difficile]

Clostridia cause severe diseases. Tetanus is rare in Switzerland because of vaccine coverage and the application of guidelines for the management of contaminated wounds. Tetanus requires wound debridement and the administration of antibiotics and anti-tetanus immune. Besides gastroenteritis, infections due to C. perfringens most often require surgery, in addition to antibiotic treatment with penicillin and clindamycin. Botulism is a rare disease caused by a toxin produced by C. botulinum that causes flaccid paralysis. The clinical syndrome must be recognized early in order to administer the antitoxin and improve the prognosis. The other, rarer species of Clostridia require surgical and antibiotic management, but their prognosis remains poor.