Botulism in 4 adults following cosmetic injections with an unlicensed, highly concentrated botulinum preparation

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.

Clinicopathological insights into an outbreak of foodborne botulism in Hamadan, Iran, in 2023: A microbiological and laboratory findings

Background and Objective

Foodborne botulism is one of the potentially fatal forms of food poisoning, usually caused by ingestion of home-canned vegetables, fruits, and dairy and fish products. This study aimed to assess the frequency of signs and symptoms in patients with botulism following the ingestion of homemade Doogh, a traditional milk-based beverage, in Hamadan, Iran in 2023. We also examined the general characteristics of the recruited patients.

Methods

During an outbreak, 21 patients were referred to the hospital because of food poisoning. All patients had a history of consumption of Doogh. After careful physical examination, all of them were hospitalized. Botulism was suspected in all patients except for the first patient.

Results

The mean age of admitted patients was 33.09 ± 18.44 years, with 23.80% being males and 76.20% females. Incubation period in our patients was 68 ± 28.48 h. Notable symptoms included diplopia (95.23%), nausea and vomiting (85.71%), blurred vision (80.95%), and dizziness (61.90%). The laboratory results were within the normal range. No deaths occurred in this patient cohort. Furthermore, botulinum spores were detected in Doogh samples collected from the outbreak, confirming the presence of Clostridium botulinum spores as a source of the outbreak.

Conclusions

This study highlights that the initial manifestations of botulism predominantly involved ophthalmologic abnormalities in most patients. Additionally, symptoms such as nausea, vomiting, and dizziness may manifest in cases of foodborne botulism. Timely diagnosis and treatment of botulism following the consumption of homemade Doogh played a crucial role in achieving positive outcomes, with no fatalities recorded in this patient cohort.

Pathogenicity and virulence of Clostridium botulinum

Clostridium botulinum, a polyphyletic Gram-positive taxon of bacteria, is classified purely by their ability to produce botulinum neurotoxin (BoNT). BoNT is the primary virulence factor and the causative agent of botulism. A potentially fatal disease, botulism is classically characterized by a symmetrical descending flaccid paralysis, which is left untreated can lead to respiratory failure and death. Botulism cases are classified into three main forms dependent on the nature of intoxication; foodborne, wound and infant. The BoNT, regarded as the most potent biological substance known, is a zinc metalloprotease that specifically cleaves SNARE proteins at neuromuscular junctions, preventing exocytosis of neurotransmitters, leading to muscle paralysis. The BoNT is now used to treat numerous medical conditions caused by overactive or spastic muscles and is extensively used in the cosmetic industry due to its high specificity and the exceedingly small doses needed to exert long-lasting pharmacological effects. Additionally, the ability to form endospores is critical to the pathogenicity of the bacteria. Disease transmission is often facilitated via the metabolically dormant spores that are highly resistant to environment stresses, allowing persistence in the environment in unfavourable conditions. Infant and wound botulism infections are initiated upon germination of the spores into neurotoxin producing vegetative cells, whereas foodborne botulism is attributed to ingestion of preformed BoNT. C. botulinum is a saprophytic bacterium, thought to have evolved its potent neurotoxin to establish a source of nutrients by killing its host.

Navigating the Complexities Involving the Identification of Botulinum Neurotoxins (BoNTs) and the Taxonomy of BoNT-Producing Clostridia

Botulinum neurotoxins are a varied group of protein toxins that share similar structures and modes of activity. They include at least seven serotypes and over forty subtypes that are produced by seven different clostridial species. These bacterial species are not limited strictly to BoNT-producers as neuro-toxigenic and non-neuro-toxigenic members have been identified within each species. The nomenclature surrounding these toxins and associated bacteria has been evolving as new isolations and discoveries have arisen, resulting in challenges in diagnostic reporting, epidemiology and food safety studies, and in the application of therapeutic products. An understanding of the intricacies regarding the nomenclature of BoNTs and BoNT-producing clostridia is crucial for communication that allows for accurate reporting of information that is pertinent to each situation.

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.

Exposure-Response Modeling and Simulation to Support Human Dosing of Botulism Antitoxin Heptavalent Product

Botulism antitoxin heptavalent (A, B, C, D, E, F, and G – Equine; BAT) product is a sterile solution of F(ab')₂ and F(ab')₂‐related antibody fragments prepared from plasma obtained from horses that have been immunized with a specific serotype of botulinum toxoid and toxin. BAT product is indicated for the treatment of symptomatic botulism following documented or suspected exposure to botulinum neurotoxin serotypes A to G in adults and pediatric patients. Pharmacokinetic and exposure‐response models were used to explore the relationship between BAT product exposure and the probability of survival, and the occurrence of relevant moderate clinical signs observed during the preclinical development of BAT product to justify the clinical dose. The predicted probability of survival in humans for all serotypes of botulinum neurotoxin was more than 95.9% following intravenous administration of one vial of BAT product. Furthermore, this BAT product dose is expected to result in significant protection against clinical signs in human adults for all botulinum neurotoxin serotypes. Our exposure response model indicates that we have sufficient antitoxin levels to give full protection at various theoretical exposure levels and, based on neutralization capacity/potency of one dose of BAT product, it is expected to exceed the amount of circulating botulinum neurotoxin.

Botulinum Toxin Type A: Adverse Events and Management

Aesthetic medicine is witnessing an increasing exploitation of all the procedures. The demand has never been higher than it is today. The number of practitioners is also increasing year by year. Consequently complications and other kinds of related troubles and procedures are also rising. Never like today is fundamental, in case of troubles, how to properly manage with the most frequent issues. In aesthetic medicine field, botulinum toxin procedures are the safest. Lot of patients are worried about botulinum toxin despite the available scientific literature. Rare short-term complications are observed. In the most of cases, nothing severe occurs if the international recommendations and the most recent guidelines are closely followed, the majority of them are injection related. This study is a review of rare or common problems that can occur and how to manage or solve the situations.

Exploring the role of botulinum toxin in critical care

INTRODUCTION

Botulinum neurotoxin (BoNT) is one of the most potent and extensively studied neurotoxins with clinical applications across several different medical specialties. This review article explores the latest evidence for therapeutic applications of BoNT in patients receiving critical management in an intensive care unit (ICU).

AREAS COVERED

The authors did a literature search in PubMed, Google Scholar, and Texas Medical Center Library database for studies describing the use of BoNT in a critical care setting. They extracted information on study design, patient selection, methodology, and results of relevant studies. Based on initial identification of 85 studies and after conducting screening, the authors identified 61 studies to be included in this review. In an ICU setting, BoNT has been used for several neurological and non-neurological indications. However, the supporting evidence is mostly limited to small observational studies.

EXPERT OPINION

The use of BoNT in this setting is largely underutilized due to paucity of well-designed clinical trials and financial barriers. Further research is needed to provide evidence for the safety and efficacy of BoNT and to optimize the dosing and injection techniques for various conditions encountered in this setting.

Infections of the Peripheral Nervous System

PURPOSE OF REVIEW

This article describes infections that affect the peripheral nervous system, including their clinical features, differential diagnoses, and treatments.

RECENT FINDINGS

Rates of pyomyositis have increased recently in the United States, possibly because of an increase in risk factors such as IV drug use, obesity, and diabetes. Other peripheral nervous system infections, such as diphtheria, have become more common in older patients secondary to a lack of revaccination or waning immunity. Although recommended treatment regimens for most infections remain unchanged over recent years, debate over the ideal dosing and route of administration continues for some infections such as tetanus and leprosy (Hansen disease).

SUMMARY

Infections of the peripheral nervous system are varied in terms of the type of infection, localization, and potential treatment. Nerve conduction studies and EMG can help determine localization, which is key to determining an initial differential diagnosis. It is important to recognize infections quickly to minimize diagnostic delays that could lead to patient morbidity and mortality.

A Monoclonal Antibody Combination against both Serotypes A and B Botulinum Toxin Prevents Inhalational Botulism in a Guinea Pig Model

Botulinum neurotoxins (BoNT) are extremely potent and can induce respiratory failure, requiring long-term intensive care to prevent death. Recombinant monoclonal antibodies (mAbs) hold considerable promise as BoNT therapeutics and prophylactics. In contrast, equine antitoxin cannot be used prophylactically and has a short half-life. Two three-mAb combinations are in development that specifically neutralize BoNT serotype A (BoNT/A) and B (BoNT/B). The three-mAb combinations addressing a single serotype provided pre-exposure prophylaxis in the guinea pig inhalation model. A lyophilized co-formulation of six mAbs, designated G03-52-01, that addresses both A and B serotypes is in development. Here, we investigated the efficacy of G03-52-01 to protect guinea pigs against an aerosol exposure challenge of BoNT/A1 or BoNT/B1. Previously, it was found that each antibody demonstrated a dose-dependent exposure and reached maximum circulating concentrations within 48 h after intramuscular (IM) or intravenous (IV) injection. Here we show that G03-52-01, in a single IM injection of G03-52-01 administered 48 h pre-exposure, protected guinea pigs against an aerosol challenge of up to 238 LD₅₀s of BoNT/A1 and 191 LD₅₀s of BoNT/B1. These data suggest that a single IM administration of G03-52-01 provides pre-exposure prophylaxis against botulism from an aerosol exposure of BoNT/A1 or BoNT/B1.

Image-guided botulinum toxin injection in the lateral abdominal wall prior to abdominal wall reconstruction surgery: review of techniques and results

Ventral hernias represent the most common complication after abdominal surgery. Loss of domain and/or large ventral hernias in patients are especially challenging for surgeons to manage, but preoperative image-guided botulinum toxin injection has emerged as an effective adjunct to abdominal wall surgery. Loss of domain is caused by chronic muscle retraction of the lateral abdominal wall and leads to an irreducible protrusion of abdominal viscera into the hernia sac. Botulinum toxin can be used in the oblique muscles as a chemical component relaxation technique to aid abdominal wall reconstruction. Intramuscular botulinum toxin injection causes functional denervation by blocking neurotransmitter acetylcholine release resulting in flaccid paralysis and elongation of lateral abdominal wall muscles, increasing the rate of fascial closure during abdominal wall reconstruction, and decreasing recurrence rates. In total, 200-300 units of onabotulinumtoxinA (Botox®) or 500 units of abobotulinumtoxinA (Dypsort®) in a 2:1 dilution with normal saline is most commonly used. Botulinum toxin can be injected with ultrasonographic, EMG, or CT guidance. Injection should be performed at least 2 weeks prior to abdominal wall reconstruction, for maximal effect during surgery. At minimum, botulinum toxin should be injected into the external and internal oblique muscles at three separate sites bilaterally for a total of six injections. Although botulinum toxin use for abdominal wall reconstruction is currently not indicated by the Food and Drug Administration, it is safe with only minor complications reported in literature.

The Effects of Preoperative Botulinum Toxin A Injection on Abdominal Wall Reconstruction

BACKGROUND

Fascial closure significantly reduces postoperative complications and hernia recurrence after abdominal wall reconstruction (AWR), but can be challenging in massive ventral hernias.

METHODS

A prospective single-institution cohort study was performed to examine the effects of preoperative injection of botulinum toxin A (BTA) in patients undergoing AWR for midline or flank hernias.

RESULTS

A total of 108 patients underwent BTA injection with average 243 units, mean 32.5 days before AWR, without complications. Comorbidities included diabetes (31%), history of smoking (27%), and obesity (mean body mass index 30.5 ± 7.7). Hernias were recurrent in 57%, massive (mean defect width 15.3 ± 5.5 cm; hernia sac volume 2154 ± 3251 cm³) and had significant loss of domain (mean 46% visceral volume outside abdominal cavity). Contamination was present in 38% of patients. Fascial closure was achieved in 91%, with 57% requiring component separation techniques (CSTs). Subxiphoidal hernias needed a form of CST in 88% compared with 50% for hernia not extending subxiphoidal (P < 0.001). Mesh augmentation was used in 98%. Postoperative complications occurred in 40%: 19% surgical site occurrences, 12% surgical site infections, and 7% respiratory failure requiring intubation, 2% mesh infection and no fascial dehiscence. Recurrence was identified in seven patients after mean 14 months of follow-up. Patients undergoing AWR with CST had more surgical site occurrences (29 versus 7%, p0.003) and respiratory failures (18 versus 0%, P = 0.002) than patients who did not require CST.

CONCLUSIONS

In patients with massive ventral hernias, the use of preoperative BTA injections for AWR is safe and is associated with high fascial closure rates and excellent recurrence rates.

Wound Botulism Caused by Botulinum Neurotoxin Type A in a Chronic Parenteral Drug Abuser

Botulism is an acute paralytic disease caused by botulinum neurotoxin (BoNT)-mediated inhibition of neurosignaling at the neuromuscular junction. BoNTs are produced by gram positive, anaerobic, spore-forming bacteria from the genus <i>Clostridium,</i>most commonly<i> Clostridium botulinum</i>. Over the last decade, a previously uncommon form of botulism, wound botulism, has increased in prevalence possibly due to the rise in parenteral drug abuse. A 53-year-old patient with a history of drug abuse presents to a rural emergency department with rapidly progressing lower extremity weakness over the past few days. He reports a recent heroin injection into right buttock and diffuse skin-popping scarring was observed throughout. The patient was treated with heptavalent botulinum antitoxin obtained from the Center for Disease Control and Prevention (CDC). A right thigh abscess culture was positive for<i> Clostridium tertium</i>, a left hip abscess culture was positive for methicillin-susceptible <i>Staphylococcus aureus</i> (MSSA), and blood culture confirmed multi-microbial bacteremia caused by <i>Staphylococcus epidermidis</i> and <i>Streptococcus mitis</i>. Serum analysis was positive for BoNT type A from a suspected concurrent<i> Clostridium botulinum</i> infection as <i>C. tertium</i> is not known to produce BoNT type A. This case report highlights the importance of early antitoxin treatment for patients with suspected wound botulism.

A review on iatrogenic botulism

Background:

With the flourishing application of botulinum toxin cosmetically and therapeutically is the emergence of iatrogenic botulism, a new type of botulism in addition to the traditional ones.

Objectives:

We aim at a comprehensive review of the clinical characteristics of iatrogenic botulism. Methods: The available publications are retrieved and studied.

Results:

Botulinum toxin blocks cholinergic transmission in the neuromuscular junctions and autonomic ganglia. The blockade can spread from the site of tissue injection to adjacent or sometimes far off structures, resulting in inadvertent disabling or even lethal effects. On literature review, weakness and dysphagia are the commonest complications of iatrogenic botulism, whereas ophthalmological and oropharyngeal symptoms are more prevalent in the cosmetic group and dyspnea in the therapeutic group. Antitoxin therapy is required in about 20% of the patients. Diagnosis of iatrogenic botulism is primarily clinical and should not be confused with the neurological diagnoses possessing similar clinical manifestations. Vigilance to the drug formulation, dosage, and administration during botulinum toxin injection are part of the preventive measures in minimizing the occurrence of iatrogenic botulism.

Conclusion:

While overlapping with the traditional types of botulism, iatrogenic botulism carries its unique clinical characteristics.

A Case of Localized, Unilateral (Cephalic) Wound Botulism

We describe a rare presentation of botulism originally presenting with exclusively unilateral cranial nerve deficits following a puncture wound to the face. Cephalic tetanus was initially suspected but laboratory testing confirmed botulism. Botulism caused by local diffusion of toxin from a contaminated head wound can be confused with cephalic tetanus.

Clinical Characteristics and Ancillary Test Results Among Patients With Botulism-United States, 2002-2015

Background

Botulism is classically described as a bilateral, symmetric, descending flaccid paralysis in an afebrile and alert patient without sensory findings. We describe the reported spectrum of clinical findings among persons >12 months of age in the United States during 2002-2015.

Methods

The Centers for Disease Control and Prevention collects clinical findings reported by physicians treating suspected cases of botulism nationwide. We analyzed symptoms and signs, and neuroimaging and cerebrospinal fluid (CSF) results. A case was defined as illness compatible with botulism with laboratory confirmation or epidemiologic link to a confirmed case, and presence or absence of at least 1 sign or symptom recorded. Physicians' differential diagnoses were evaluated.

Results

Clinical information was evaluated for 332 botulism cases; data quality and completeness were variable. Most had no fever (99%), descending paralysis (93%), no mental status change (91%), at least 1 ocular weakness finding (84%), and neuroimaging without acute changes (82%). Some had paresthesias (17%), elevated CSF protein level (13%), and other features sometimes considered indicative of alternative diagnoses. Five of 71 (7%) cases with sufficient information were reported to have atypical findings (eg, at least 1 cranial nerve finding that was unilateral or ascending paralysis). Illnesses on the physician differential included Guillain-Barré syndrome (99 cases) and myasthenia gravis (76 cases) and, rarely, gastrointestinal-related illness (5 cases), multiple sclerosis (3 cases), sepsis (3 cases), and Lyme disease (2 cases).

Conclusions

Our analysis illustrates that classic symptoms and signs were common among patients with botulism but that features considered atypical were reported by some physicians. Diagnosis can be challenging, as illustrated by the broad range of illnesses on physician differentials.

Clinical Features of Foodborne and Wound Botulism: A Systematic Review of the Literature, 1932-2015

Background

Botulism is a rare, potentially fatal paralytic illness caused by neurotoxins. To inform the evaluation of patients with suspected botulism, we conducted a systematic review to describe the clinical features of botulism.

Methods

We searched Medline Ovid, Embase Dialog, Embase Ovid, Cumulative Index to Nursing and Allied Health Literature (CINAHL) EBSCO, Global Health Ovid, Cochrane Library, Scopus, and ClinicalTrials.gov for English language articles through May 2015. Information abstracted included demographics, signs and symptoms, laboratory results, and clinical outcome for foodborne and wound botulism patients confirmed by laboratory testing, epidemiologic link, or association with an outbreak. The review followed PRISMA guidelines and was registered with PROSPERO (CRD42015024784).

Results

We identified 402 patients from 233 articles published in English between 1932 and 2015. Most cases (n = 346 [86%]) were foodborne botulism and most (n = 263 [65%]) were associated with an outbreak. The median incubation period was 1 day, and the median time from illness onset to hospital admission was 2 days. Shortness of breath, dyspnea, or respiratory distress or failure at hospital admission was reported in 169 (42%) patients; 71 (42%) reported respiratory involvement without report of extremity weakness. Among 154 patients for whom the hospital day of intubation was reported, 134 (87%) were intubated on the first or second hospital day.

Conclusions

Botulism patients can experience a range of signs and symptoms. Respiratory involvement may occur early in the illness and can occur without preceding extremity weakness. Clinicians and public health departments preparing for and responding to botulism events should use this information to guide the evaluation of suspected botulism patients.

Monoclonal Antibody Combinations Prevent Serotype A and Serotype B Inhalational Botulism in a Guinea Pig Model

Botulinum neurotoxins (BoNT) are some of the most toxic proteins known, with a human LD₅₀ of ~1 ng/kg. Equine antitoxin has a half-life in circulation of less than 1 day and is limited to a treatment rather than a prevention indication. The development of monoclonal antibodies (mAbs) may represent an alternative therapeutic option that can be produced at high quantities and of high quality and with half-lives of >10 days. Two different three mAb combinations are being developed that specifically neutralize BoNT serotypes A (BoNT/A) and B (BoNT/B). We investigated the pharmacokinetics of the anti-BoNT/A and anti-BoNT/B antibodies in guinea pigs (Cavia porcellus) and their ability to protect guinea pigs against an aerosol challenge of BoNT/A1 or BoNT/B1. Each antibody exhibited dose-dependent exposure and reached maximum circulating concentrations within 48 h post intraperitoneal or intramuscular injection. A single intramuscular dose of the three mAb combination protected guinea pigs against an aerosol challenge dose of 93 LD₅₀ of BoNT/A1 and 116 LD₅₀ of BoNT/B1 at 48 h post antibody administration. These mAbs are effective in preventing botulism after an aerosol challenge of BoNT/A1 and BoNT/B1 and may represent an alternative to vaccination to prevent type A or B botulism in those at risk of BoNT exposure.

Botulism Outbreak in a Regional Community Hospital: Lessons Learned in Transfer and Transport Considerations

Botulism is a potentially lethal disease caused by a toxin released by Clostridium botulinum. Outbreaks of botulism from food sources can lead to a Mass Casualty Incident (MCI) involving sometimes hundreds of individuals. We report on a recent outbreak of botulism treated at a regional community hospital with a focus on emergency medical services (EMS) response and transport considerations. Case Presentation: There were 53 patient evaluated for botulism at the sending facility. In total, 11 botulism exposures required intubation at the sending facility. Twenty-four patients were ultimately transported by critical care capable ALS crews with the majority (16) of these transports occurred in the first 24 hours. There was one fatality in the first days of the outbreak and a second death that occurred in a patient who died after long-term acute care (LTAC) placement several months after hospital discharge. Conclusion: Local EMS providers and public safety officers have a critical role in identifying and following up on potentially exposed botulism cases. The organization of transporting agencies and the logistics of transfer turned out to be 2 opportunities for improvement in response to this mass casualty incident.

"Saving Face": An Online Study of the Injecting Use of DIY Botox and Dermal Filler Kits

This study reports on an empirically underdocumented practice in contemporary aesthetic enhancement culture, the self-injection of unregulated DIY Botox and dermal filler kits purchased online. Data were collected from 4 online discussion forums containing disclosures in relation to use of DIY kits and analyzed using ethnographic content analysis. Motivation to source DIY Botox and dermal fillers online was grounded in desire to avoid financial cost of professional services and a lack of confidence in practitioners. Future intentions to order online raw materials and "formulas" to prepare dermal fillers at home were expressed. Individuals taught themselves to inject through watching YouTube tutorials and downloading Botox injection maps from the Internet. Although individuals demonstrated awareness of the health risks involved with self-injection of unregulated products, this was not a deterrent. Future research is warranted to document the injecting practices and health outcomes of individuals who inject DIY Botox and dermal filler kits to inform targeted harm reduction interventions by health-care practitioners.

Therapeutic efficacy of equine botulism antitoxin in Rhesus macaques

Background

There are currently no licensed vaccines available for prevention of botulism in humans. The vaccination is not desirable due to expanding therapeutic indications of botulinum toxins. The only available specific treatment for botulism is antitoxin to remove circulating toxin, thus, preventing further neuronal damage. BAT^® (Botulism Antitoxin Heptavalent (A, B, C, D, E, F, G)—(Equine)) has been developed and its therapeutic efficacy evaluated against botulinum neurotoxin serotype A (BoNT/A) in Rhesus macaques.

Methods and findings

In a post-exposure prophylaxis (PEP) study, animals were exposed to 4x LD₅₀/kg of BoNT/A and administered intravenously with either BAT (1x or 0.1x scaled human dose), or placebo at 4 hours post-exposure. The animals were monitored for 14 days. For the therapeutic intervention studies, animals were exposed to a 1.7x LD₅₀/kg of BoNT/A and treated intravenously with either placebo or BAT at a 1x scaled human dose at the onset of clinical signs. Animals were monitored on an hourly basis for 14 or 21 days. In the PEP study, all animals tolerated equine based antitoxin without any adverse clinical signs. A 100% survival was observed in groups treated with the BAT compared to 0% survival in those treated with the placebo (p<0.001, Fisher’s exact test). BAT antitoxin prevented the development of signs of neurotoxicity of botulinum toxin. In a therapeutic study, treatment with the BAT at scaled 1x human dose after the onset of clinical signs significantly enhanced survival compared to the placebo (46.6% vs. 0%, p<0.0001, Fisher’s exact test). Additionally, treatment with the BAT delayed the progression of signs (muscular weakness, respiratory distress, oral/nasal discharge) of toxin intoxication and reduced the severity of the disease.

Conclusions

A single dose of BAT, when administered to symptomatic monkeys, resulted in a statistically significant survival benefit compared to the placebo. Additionally, BAT completely protected monkeys from the clinical signs of intoxication and subsequent death when administered as PEP treatment. These data in part supported the licensure of BAT under the Animal Rule in the United States by the Food and Drug Administration.

Use-dependent potentiation of voltage-gated calcium channels rescues neurotransmission in nerve terminals intoxicated by botulinum neurotoxin serotype A

Botulinum neurotoxins (BoNTs) are highly potent toxins that cleave neuronal SNARE proteins required for neurotransmission, causing flaccid paralysis and death by asphyxiation. Currently, there are no clinical treatments to delay or reverse BoNT-induced blockade of neuromuscular transmission. While aminopyridines have demonstrated varying efficacy in transiently reducing paralysis following BoNT poisoning, the precise mechanisms by which aminopyridines symptomatically treat botulism are not understood. Here we found that activity-dependent potentiation of presynaptic voltage-gated calcium channels (VGCCs) underlies 3,4-diaminopyridine (3,4-DAP)-mediated rescue of neurotransmission in central nervous system synapses and mouse diaphragm neuromuscular junctions fully intoxicated by BoNT serotype A. Combinatorial treatments with 3,4-DAP and VGCC agonists proved synergistic in restoring suprathreshold endplate potentials in mouse diaphragms fully intoxicated by BoNT/A. In contrast, synapses fully intoxicated by BoNT serotypes D or E were refractory to synaptic rescue by any treatment. We interpret these data to propose that increasing the duration or extent of VGCC activation prolongs the opportunity for low-efficiency fusion by fusogenic complexes incorporating BoNT/A-cleaved SNAP-25. The identification of VGCC agonists that rescue neurotransmission in BoNT/A-intoxicated synapses provides compelling evidence for potential therapeutic utility in some cases of human botulism.

A camelid single-domain antibody neutralizes botulinum neurotoxin A by blocking host receptor binding

Antibody treatment is currently the only available countermeasure for botulism, a fatal illness caused by flaccid paralysis of muscles due to botulinum neurotoxin (BoNT) intoxication. Among the seven major serotypes of BoNT/A-G, BoNT/A poses the most serious threat to humans because of its high potency and long duration of action. Prior to entering neurons and blocking neurotransmitter release, BoNT/A recognizes motoneurons via a dual-receptor binding process in which it engages both the neuron surface polysialoganglioside (PSG) and synaptic vesicle glycoprotein 2 (SV2). Previously, we identified a potent neutralizing antitoxin against BoNT/A1 termed ciA-C2, derived from a camelid heavy-chain-only antibody (VHH). In this study, we demonstrate that ciA-C2 prevents BoNT/A1 intoxication by inhibiting its binding to neuronal receptor SV2. Furthermore, we determined the crystal structure of ciA-C2 in complex with the receptor-binding domain of BoNT/A1 (H_CA1) at 1.68 Å resolution. The structure revealed that ciA-C2 partially occupies the SV2-binding site on H_CA1, causing direct interference of H_CA1 interaction with both the N-glycan and peptide-moiety of SV2. Interestingly, this neutralization mechanism is similar to that of a monoclonal antibody in clinical trials, despite that ciA-C2 is more than 10-times smaller. Taken together, these results enlighten our understanding of BoNT/A1 interactions with its neuronal receptor, and further demonstrate that inhibiting toxin binding to the host receptor is an efficient countermeasure strategy.

Botulinum Neurotoxins: Biology, Pharmacology, and Toxicology

The study of botulinum neurotoxins (BoNT) is rapidly progressing in many aspects. Novel BoNTs are being discovered owing to next generation sequencing, but their biologic and pharmacological properties remain largely unknown. The molecular structure of the large protein complexes that the toxin forms with accessory proteins, which are included in some BoNT type A1 and B1 pharmacological preparations, have been determined. By far the largest effort has been dedicated to the testing and validation of BoNTs as therapeutic agents in an ever increasing number of applications, including pain therapy. BoNT type A1 has been also exploited in a variety of cosmetic treatments, alone or in combination with other agents, and this specific market has reached the size of the one dedicated to the treatment of medical syndromes. The pharmacological properties and mode of action of BoNTs have shed light on general principles of neuronal transport and protein-protein interactions and are stimulating basic science studies. Moreover, the wide array of BoNTs discovered and to be discovered and the production of recombinant BoNTs endowed with specific properties suggest novel uses in therapeutics with increasing disease/symptom specifity. These recent developments are reviewed here to provide an updated picture of the biologic mechanism of action of BoNTs, of their increasing use in pharmacology and in cosmetics, and of their toxicology.

Safety and Patient Satisfaction of AbobotulinumtoxinA for Aesthetic Use: A Systematic Review

A systematic review of the published literature (from January 2000 to January 2016) to ascertain the safety of, and patient satisfaction with, the aesthetic use of abobotulinumtoxinA was conducted. In addition to the licensed indications, other special populations were considered for discussion. The potential impact of neutralizing antibodies and systemic toxicity were also addressed. A total of 364 papers were screened and 86 were found to be relevant to the population, intervention(s), and outcomes stipulated in the protocol. The safety and patient satisfaction data from these publications are discussed in this review.

Botulism mortality in the USA, 1975-2009

Botulism had mortality rates >60% before the 1950s. We reviewed confirmed botulism cases in the USA during 1975-2009 including infant, foodborne, wound, and other/unknown acquisition categories, and calculated mortality ratios. We created a multivariate logistic regression model for non-infant cases (foodborne, wound, and other/unknown). Overall mortality was 3.0% with 109 botulism-related deaths among 3,618 botulism cases [18 (<1%) deaths among 2,352 infant botulism cases, 61 (7.1%) deaths among 854 foodborne botulism cases, 18 (5.0%) deaths among 359 wound botulism cases, and 12 (22.6%) deaths among 53 other/unknown botulism cases]. Mortality among all cases increased with age; it was lowest among infants (0.8%) and highest among persons ≥80 years old (34.4%). Toxin type F had higher mortality (13.8%) than types A, B, or E (range, 1.4% to 4.1%). Efforts to reduce botulism mortality should target non-infant transmission categories and older adults.

The role of botulinum toxin A in treating neurogenic bladder

Neurogenic detrusor overactivity (NDO) can result in lower and upper urinary tract complications and eventually even in end-stage kidney failure. Since the driving force of this clinical cascade is high bladder pressure, controlling intravesical pressure in NDO patients improves both quality of life and life-expectancy in these patients. Botulinum toxin A (BTX-A) has proven its efficacy in reducing intravesical pressure and in reducing incontinence episodes. BTX-A also improves quality of life in patients with NDO. Both onabotulinumtoxinA (Botox^®, Allergan, Irvine, USA) and abobotulinumtoxinA (Dysport^®, Ipsen, Paris, France) have a level A recommendation for NDO-treatment. The recommended dose for intradetrusor injections in NDO patients is 200 U of onabotulinumtoxinA or 500 U of abobotulinumtoxinA. The drug is generally administered extratrigonal in the detrusor muscle, via cystoscopic guided injection at 20 sites in 1 mL injections. Intradetrusor BTX-A injections are safe, with mostly local complications such as urinary tract infection and high post-void residual or retention. The effect of the toxin lasts for approximately 9 months. Repeat injections can be performed without loss of efficacy. Different injection techniques, novel ways of BTX-A administration, eliminating the need for injection or new BTX-A types with better/longer response rates could change the field in the future.

Infant botulism: review and clinical update

Botulism is a rare neuromuscular condition, and multiple clinical forms are recognized. Infant botulism was first identified in the 1970s, and it typically occurs in infants younger than 1 year of age who ingest Clostridium botulinum spores. A specific treatment for infant botulism, intravenous botulism immunoglobulin (BIG-IV or BabyBIG®), was developed in 2003, and this treatment has substantially decreased both morbidity and hospital costs associated with this illness. This article will review the pathogenesis of infant botulism as well as the epidemiology, clinical manifestations, diagnosis, and treatment of this condition.

Botulinum toxin type A products are not interchangeable: a review of the evidence

Botulinum toxin type A (BoNTA) products are injectable biologic medications derived from Clostridium botulinum bacteria. Several different BoNTA products are marketed in various countries, and they are not interchangeable. Differences between products include manufacturing processes, formulations, and the assay methods used to determine units of biological activity. These differences result in a specific set of interactions between each BoNTA product and the tissue injected. Consequently, the products show differences in their in vivo profiles, including preclinical dose response curves and clinical dosing, efficacy, duration, and safety/adverse events. Most, but not all, published studies document these differences, suggesting that individual BoNTA products act differently depending on experimental and clinical conditions, and these differences may not always be predictable. Differentiation through regulatory approvals provides a measure of confidence in safety and efficacy at the specified doses for each approved indication. Moreover, the products differ in the amount of study to which they have been subjected, as evidenced by the number of publications in the peer-reviewed literature and the quantity and quality of clinical studies. Given that BoNTAs are potent biological products that meet important clinical needs, it is critical to recognize that their dosing and product performance are not interchangeable and each product should be used according to manufacturer guidelines.

Genetic characterization and comparison of Clostridium botulinum isolates from botulism cases in Japan between 2006 and 2011

Genetic characterization was performed for 10 group I Clostridium botulinum strains isolated from botulism cases in Japan between 2006 and 2011. Of these, 1 was type A, 2 were type B, and 7 were type A(B) {carrying a silent bont/B [bont/(B)] gene} serotype strains, based on botulinum neurotoxin (BoNT) production. The type A strain harbored the subtype A1 BoNT gene (bont/A1), which is associated with the ha gene cluster. The type B strains carried bont/B5 or bont/B6 subtype genes. The type A(B) strains carried bont/A1 identical to that of type A(B) strain NCTC2916. However, bont/(B) genes in these strains showed single-nucleotide polymorphisms (SNPs) among strains. SNPs at 2 nucleotide positions of bont/(B) enabled classification of the type A(B) strains into 3 groups. Pulsed-field gel electrophoresis (PFGE) and multiple-locus variable-number tandem-repeat analysis (MLVA) also provided consistent separation results. In addition, the type A(B) strains were separated into 2 lineages based on their plasmid profiles. One lineage carried a small plasmid (5.9 kb), and another harbored 21-kb plasmids. To obtain more detailed genetic information about the 10 strains, we sequenced their genomes and compared them with 13 group I C. botulinum genomes in a database using whole-genome SNP analysis. This analysis provided high-resolution strain discrimination and enabled us to generate a refined phylogenetic tree that provides effective traceability of botulism cases, as well as bioterrorism materials. In the phylogenetic tree, the subtype B6 strains, Okayama2011 and Osaka05, were distantly separated from the other strains, indicating genomic divergence of subtype B6 strains among group I strains.

Botulinum neurotoxins: genetic, structural and mechanistic insights

Botulinum neurotoxins (BoNTs) are produced by anaerobic bacteria of the genus Clostridium and cause a persistent paralysis of peripheral nerve terminals, which is known as botulism. Neurotoxigenic clostridia belong to six phylogenetically distinct groups and produce more than 40 different BoNT types, which inactivate neurotransmitter release owing to their metalloprotease activity. In this Review, we discuss recent studies that have improved our understanding of the genetics and structure of BoNT complexes. We also describe recent insights into the mechanisms of BoNT entry into the general circulation, neuronal binding, membrane translocation and neuroparalysis.

Botulinum toxin A, brain and pain

Botulinum neurotoxin type A (BoNT/A) is one of the most potent toxins known and a potential biological threat. At the same time, it is among the most widely used therapeutic proteins used yearly by millions of people, especially for cosmetic purposes. Currently, its clinical use in certain types of pain is increasing, and its long-term duration of effects represents a special clinical value. Efficacy of BoNT/A in different types of pain has been found in numerous clinical trials and case reports, as well as in animal pain models. However, sites and mechanisms of BoNT/A actions involved in nociception are a matter of controversy. In analogy with well known neuroparalytic effects in peripheral cholinergic synapses, presently dominant opinion is that BoNT/A exerts pain reduction by inhibiting peripheral neurotransmitter/inflammatory mediator release from sensory nerves. On the other hand, growing number of behavioral and immunohistochemical studies demonstrated the requirement of axonal transport for BoNT/A's antinociceptive action. In addition, toxin's enzymatic activity in central sensory regions was clearly identified after its peripheral application. Apart from general pharmacology, this review summarizes the clinical and experimental evidence for BoNT/A antinociceptive activity and compares the data in favor of peripheral vs. central site and mechanism of action. Based on literature review and published results from our laboratory we propose that the hypothesis of peripheral site of BoNT/A action is not sufficient to explain the experimental data collected up to now.

High sensitivity detection of active botulinum neurotoxin by glyco-quantitative polymerase chain-reaction

The sensitive detection of highly toxic botulinum neurotoxin (BoNT) from Clostridium botulinum is of critical importance because it causes human illnesses if foodborne or introduced in wounds and as an iatrogenic substance. Moreover, it has been recently considered a possible biological warfare agent. Over the past decade, significant progress has been made in BoNT detection technologies, including mouse lethality assays, enzyme-linked immunosorbent assays, and endopeptidase assays and by mass spectrometry. Critical assay requirements, including rapid assay, active toxin detection, sensitive and accurate detection, still remain challenging. Here, we present a novel method to detect active BoNTs using a Glyco-quantitative polymerase chain-reaction (qPCR) approach. Sialyllactose, which interacts with the binding-domain of BoNTs, is incorporated into a sialyllactose-DNA conjugate as a binding-probe for active BoNT and recovered through BoNT-immunoprecipitation. Glyco-qPCR analysis of the bound sialyllactose-DNA is then used to detect low attomolar concentrations of BoNT and attomolar to femtomolar concentrations of BoNT in honey, the most common foodborne source of infant botulism.

Effects of enzymatically inactive recombinant botulinum neurotoxin type A at the mouse neuromuscular junctions

Botulinum neurotoxin A (BoNT/A) is used clinically to treat several neurological and metabolic diseases. However, the mechanisms that underlie the clinical use of the toxin remain still to be elusive. BoNT/A inhibits acetylcholine (ACh) release at the motor nerve terminals (MNT) and causes neuroparalysis. The toxic effects of BoNT/A at the MNT occur in sub-pico molar range, and it is invaluable to determine the half-life and the persistence of catalytic activity of the toxin to develop therapeutics against BoNT/A intoxication. However, the use of extremely low concentrations of BoNT/A in cellular, or animal models due to high toxicity makes it difficult to determine new cellular mechanisms and binding or interacting partners of BoNT/A. In order to address this, a catalytically deactivated, non-toxic version of BoNT/A, designated as DrBoNT/A, was characterized. DrBoNT/A lacks endoprotease activity (SNAP-25 cleavage) at concentrations as high as 46,875-fold, compared to wild-type BoNT/A. Unlike BoNT/A injection (3.2 pg), injection of the recombinant product (150 ng or 3.2 pg) into mouse hind limbs failed to cause neuroparalysis as exhibited by the lack of inhibition of toe spread reflex (ability of the mouse to spread its hindlimb toes), and inhibit ACh release at the MNT. The in vitro experiments also demonstrate that DrBoNT/A uptake (at concentrations equivalent to BoNT/A), internalization and localization at the MNT remained unaltered. In addition, modeling studies support that DrBoNT/A lacked the zinc binding ability, and the ability to directly participate in the hydrolysis of SNAP-25 substrate. Collectively, we demonstrate that DrBoNT/A is non-toxic to the MNT and can be used as a surrogate tool to understand the mechanism by which BoNT/A modulates signal transduction mechanisms.

DNA electroporation in rabbits as a method for generation of high-titer neutralizing antisera: examples of the botulinum toxins types A, B, and E

Raising high titer antibodies in animals is usually performed by protein immunization, which requires the long and sometimes difficult step of production of the recombinant protein. DNA immunization is an alternative to recombinant proteins, only requiring the building of an eukaryotic expression plasmid. Thanks to efficient DNA delivery techniques such as in vivo electroporation, DNA vaccination has proven useful the last few years. In this work, we have shown that it is possible to raise very high antibody titers in rabbit by DNA electroporation of an antigen encoding plasmid in the skeletal muscle with the right set of electrodes and rabbit strain. In a model of botulinum toxins types A and E, the neutralizing titers obtained after three treatments were high enough to fit the European Pharmacopeia, while it did not for type B toxin. Furthermore, the raised antibodies have high avidity and are suitable for in vitro and in vivo immunodetection of proteins.

Substrates and controls for the quantitative detection of active botulinum neurotoxin in protease-containing samples

Botulinum neurotoxins (BoNTs) are used in a wide variety of medical applications, but there is limited pharmacokinetic data on active BoNT. Monitoring BoNT activity in the circulation is challenging because BoNTs are highly toxic and are rapidly taken up by neurons and removed from the bloodstream. Previously we reported a sensitive BoNT "Assay with a Large Immunosorbent Surface Area" that uses conversion of fluorogenic peptide substrates to measure the intrinsic endopeptidase activity of bead-captured BoNT. However, in complex biological samples, protease contaminants can also cleave the substrates, reducing sensitivity and specificity of the assay. Here, we present a novel set of fluorogenic peptides that serve as BoNT-specific substrates and protease-sensitive controls. BoNT-cleavable substrates contain a C-terminal Nle, while BoNT-noncleavable controls contain its isomer ε-Ahx. The substrates are cleaved by BoNT subtypes A1-A3 and A5. Substrates and control peptides can be cleaved by non-BoNT proteases (e.g., trypsin, proteinase K, and thermolysin) while obeying Michaelis-Menten kinetics. Using this novel substrate/control set, we studied BoNT/A1 activity in two mouse models of botulism. We detected BoNT/A serum activities ranging from ~3600 to 10 amol/L in blood of mice that had been intravenously injected 1 h prior with BoNT/A1 complex (100 to 4 pg/mouse). We also detected the endopeptidase activity of orally administered BoNT/A1 complex (1 μg) in blood 5 h after administration; activity was greatest 7 h after administration. Redistribution and elevation rates for active toxin were measured and are comparable to those reported for inactive toxin.

[Anaerobic bacteria 150 years after their discovery by Pasteur]

In 2011 we celebrated the 150th anniversary of the discovery of anaerobic bacteria by Louis Pasteur. The interest of the biomedical community on such bacteria is still maintained, and is particularly focused on Clostridium difficile. In the past few years important advances in taxonomy have been made due to the genetic, technological and computing developments. Thus, a significant number of new species related to human infections have been characterised, and some already known have been reclassified. At pathogenic level some specimens of anaerobic microflora, that had not been isolated from human infections, have been now isolated in some clinical conditions. There was emergence (or re-emergence) of some species and clinical conditions. Certain anaerobic bacteria have been associated with established infectious syndromes. The virulence of certain strains has increased, and some hypotheses on their participation in certain diseases have been given. In terms of diagnosis, the routine use of MALDI-TOF has led to a shortening of time and a cost reduction in the identification, with an improvement directly related to the improvement of data bases. The application of real-time PCR has been another major progress, and the sequencing of 16srRNA gene and others is currently a reality for several laboratories. Anaerobes have increased their resistance to antimicrobial agents, and the emergence of resistance to carbapenems and metronidazole, and multi-resistance is a current reality. In this situation, linezolid could be an effective alternative for Bacteroides. Fidaxomicin is the only anti-anaerobic agent introduced in the recent years, specifically for the diarrhoea caused by C.difficile. Moreover, some mathematical models have also been proposed in relation with this species.

Abo-, inco-, ona-, and rima-botulinum toxins in clinical therapy: a primer

Botulinum neurotoxin (BoNT) is an acetylcholine release inhibitor and a neuromuscular-blocking agent used for the treatment of a variety of medical and cosmetic indications. Currently, in the United States, there are four BoNT formulations licensed for use: abobotulinumtoxinA, incobotulinumtoxinA, onabotulinumtoxinA, and rimabotulinumtoxinB. These revised name designations were established to reinforce the understanding that each BoNT product has an individual potency and is not interchangeable with any other BoNT product. The therapeutic use of BoNTs is expanding and new formulations are on the horizon. This article is a primer that describes distinctions among currently available, licensed BoNT formulations. Toxin pharmacology, product characteristics, storage, handling, preparation, and dosages will be reviewed. In addition, issues related to dose equivalency ratios, immunogenicity, potency, and toxin spread will be discussed. Therapeutic indications and safety are discussed briefly. Knowledge of the available and licensed BoNT formulations and the ability to make distinctions in toxin pharmacology, product characteristics, and indications are vital for product selection, preparation, drug information, avoidance of drug errors, quality assurance, and patient safety.