Recent advances in infant botulism

Production of monoclonal antibodies against botulinum neurotoxin in Nicotiana benthamiana

Botulism is a fatal neurologic disease caused by the botulinum toxin (BoNT) produced by Clostridium botulinum. It is a rare but highly toxic disease with symptoms, such as cramps, nausea, vomiting, diarrhea, dysphagia, respiratory failure, muscle weakness, and even death. Currently, two types of antitoxin are used: equine-derived heptavalent antitoxin and human-derived immunoglobulin (BabyBIG®). However, heptavalent treatment may result in hypersensitivity, whereas BabyBIG®, has a low yield. The present study focused on the development of three anti-BoNT monoclonal antibodies (mAbs), 1B18, C25, and M2, in Nicotiana benthamiana. The plant-expressed mAbs were purified and examined for size, purity and integrity by SDS-PAGE, western blotting and size-exclusion chromatography. Analysis showed that plant-produced anti-BoNT mAbs can fully assemble in plants, can be purified in a single purification step, and mostly remain as monomeric proteins. The efficiency of anti-BoNT mAbs binding to BoNT/A and B was then tested. Plant-produced 1B18 retained its ability to recognize both mBoNT/A1 and ciBoNT/B1. At the same time, the binding specificities of two other mAbs were determined: C25 for mBoNT/A1 and M2 for ciBoNT/B1. In conclusion, our results confirm the use of plants as an alternative platform for the production of anti-BoNT mAbs. This plant-based technology will serve as a versatile system for the development botulism immunotherapeutics.

That head lag is impressive! Infantile botulism in the NICU: a case report

BACKGROUND

Infantile botulism (IB) is a devastating and potentially life-threatening neuromuscular disorder resulting from intestinal colonization by Clostridium botulinum and the resultant toxin production. It can present with constipation, descending paralysis, and, potentially, respiratory failure. Botulism is a diagnosis that is more commonly seen in the pediatric intensive care unit (PICU) or on the general pediatric wards and would not typically be managed in the neonatal intensive care unit (NICU), and therefore requires high clinical suspicion to ensure prompt diagnosis and treatment.

CASE PRESENTATION

We discuss a case where an infant from central Pennsylvania presented to a Level IV NICU rather than to the PICU for an evaluation for sepsis and was uniquely diagnosed with IB. The infant presented with poor oral feeding and reduced oral intake, hypothermia, and lethargy. His symptoms progressed into hypoxia and acute respiratory failure. Interestingly, this infant had no known exposure to honey or any other identifiable sources of botulism contact. The infant's twin brother and the other infants who attended the mother's in-home daycare remained asymptomatic. This infant was initially evaluated and managed for a potential infectious etiology. However, a diagnosis of IB was suspected, and was later confirmed through the detection of botulinum toxin in the infant's stools. A high level of suspicion allowed for timely treatment with Botulism Immune Globulin neutralizing antibodies (BabyBIG), even prior to confirmatory testing. We describe the process of obtaining BabyBIG, as well as the natural course of illness after treatment in our patient who ultimately made a complete recovery.

CONCLUSIONS

This case highlights the importance of considering infantile botulism as a diagnostic possibility even in the absence of risk factors, and the need for vigilance in diagnosing and treating this rare but potentially life-threatening condition. With timely recognition, subsequent treatment with BabyBIG, and supportive care, infants with infantile botulism can be expected to recover completely. This information is particularly important for neonatologists providing care for infants outside the neonatal period, especially during times of high patient census and resulting overflow of pediatric admissions in the NICU.

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.

Infant Botulism, Israel, 2007-2021

Infant botulism (IB) is an intestinal toxemia that manifests as descending paralysis, constipation, and, in some cases, respiratory failure. Laboratory-confirmed IB cases are rare, and recent data in Israel are lacking. We conducted a national multicenter retrospective study of laboratory-confirmed IB cases reported in Israel during 2007-2021. A total of 8 cases were reported during the study period. During 2019-2021, incidence may have increased because of a cluster of 5 cases. Infant median age for diagnosis was 6.5 months, older than previously reported (3 months). Most cases occurred during March-July. Honey consumption was reported in 1 case, and possible environmental risk factors (living nearby rural or construction areas, dust exposure, and having a father who works as a farmer) were reported in 6 cases. Although IB is rare, its incidence in Israel may have increased over recent years, and its epidemiology and risk factors differ from cases reported previously in Israel.

Toxemia in Human Naturally Acquired Botulism

Human botulism is a severe disease characterized by flaccid paralysis and inhibition of certain gland secretions, notably salivary secretions, caused by inhibition of neurotransmitter release. Naturally acquired botulism occurs in three main forms: food-borne botulism by ingestion of preformed botulinum neurotoxin (BoNT) in food, botulism by intestinal colonization (infant botulism and intestinal toxemia botulism in infants above one year and adults), and wound botulism. A rapid laboratory confirmation of botulism is required for the appropriate management of patients. Detection of BoNT in the patient's sera is the most direct way to address the diagnosis of botulism. Based on previous published reports, botulinum toxemia was identified in about 70% of food-borne and wound botulism cases, and only in about 28% of infant botulism cases, in which the diagnosis is mainly confirmed from stool sample investigation. The presence of BoNT in serum depends on the BoNT amount ingested with contaminated food or produced locally in the intestine or wound, and the timeframe between serum sampling and disease onset. BoNT levels in patient's sera are most frequently low, requiring a highly sensitive method of detection. Mouse bioassay is still the most used method of botulism identification from serum samples. However, in vitro methods based on BoNT endopeptidase activity with detection by mass spectrometry or immunoassay have been developed and depending on BoNT type, are more sensitive than the mouse bioassay. These new assays show high specificity for individual BoNT types and allow more accurate differentiation between positive toxin sera from botulism and autoimmune neuropathy patients.

Production and characterization of a neutralizing antibody against botulinum neurotoxin A

As a category A toxic, the botulinum toxin(BoNT) is responsible for human botulism with an estimated lethal dose of 1 ng/kg which greatly increases the potential risk of use as bioweapons. Therefore, the development of anti-BoNT antibodies is urgent. In this paper, the H_C domain of BoNT/A was purified and immunized with Balb/c mice. Monoclonal antibodies were screened against BoNT/A from 55 stable positive hybridoma cell lines, and one with the strongest neutralizing activity, designated as ML06, was subcloned, sequenced, and classified as IgG1(κ) subclass. The mouse protection assays showed that ML06 can neutralize the toxin of BoNT/A effectively both in vitro and in vivo, in a dose-dependent manner. The therapeutic assays showed that only 20% of mice injected with 4 LD₅₀ BoNT/A can survive another injection of ML06 after 4 h. The prophylaxis assays showed the residual ML06 from mice injected with ML06 two weeks ago can protect mice against 4 LD₅₀ BoNT/A challenge completely. Collectively, our results indicated that ML06 served as a good candidate for further development of immune therapeutics for BoNT/A.

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.

Neuronal selectivity of botulinum neurotoxins

Botulinum neurotoxins (BoNTs) are highly potent toxins responsible for a severe disease, called botulism. They are also efficient therapeutic tools with an increasing number of indications ranging from neuromuscular dysfunction to hypersecretion syndrome, pain release, depression as well as cosmetic application. BoNTs are known to mainly target the motor-neurons terminals and to induce flaccid paralysis. BoNTs recognize a specific double receptor on neuronal cells consisting of gangliosides and synaptic vesicle protein, SV2 or synaptotagmin. Using cultured neuronal cells, BoNTs have been established blocking the release of a wide variety of neurotransmitters. However, BoNTs are more potent in motor-neurons than in the other neuronal cell types. In in vivo models, BoNT/A impairs the cholinergic neuronal transmission at the motor-neurons but also at neurons controlling secretions and smooth muscle neurons, and blocks several neuronal pathways including excitatory, inhibitory, and sensitive neurons. However, only a few reports investigated the neuronal selectivity of BoNTs in vivo. In the intestinal wall, BoNT/A and BoNT/B target mainly the cholinergic neurons and to a lower extent the other non-cholinergic neurons including serotonergic, glutamatergic, GABAergic, and VIP-neurons. The in vivo effects induced by BoNTs on the non-cholinergic neurons remain to be precisely investigated. We report here a literature review of the neuronal selectivity of BoNTs.

Type F Infant Botulism: Investigation of Recent Clusters and Overview of This Exceedingly Rare Disease

From 1976 to 2016, neurotoxigenic Clostridium baratii type F caused 18 (<0.5%) reported US infant botulism cases. Six cases occurred during 2012-2013; no common source was identified. Type F infant botulism mostly occurs in very young infants and typically presents more rapidly and severely than illness caused by types A and B botulinum neurotoxin.

Infant Botulism in the Very Young Neonate: A Case Series

Background  Though botulism is a rare disease overall, all infants younger than 1 year of age are at risk of contracting infant botulism, the most prevalent form reported in the United States. Nonetheless, infant botulism is frequently omitted from the differential diagnosis of the very young neonate exclusively due to age, and the diagnosis is often only considered secondarily after a costly and prolonged work up is undertaken. Delayed diagnosis can lead not only to unnecessary testing but also to prolonged hospital stay and increased morbidity. Case  This case series highlights three critically ill neonates, all younger than 30 days, who presented to our neonatal intensive care unit and were eventually diagnosed with infant botulism. The initial diagnostic dilemma is described for each of these patients and highlights the importance of early recognition of the main symptoms, in addition to consideration of important potential coinciding conditions.

Botulinum neurotoxin type B uses a distinct entry pathway mediated by CDC42 into intestinal cells versus neuronal cells

Botulinum neurotoxins (BoNTs) are responsible for severe flaccid paralysis by inhibiting the release of acetylcholine at the neuromuscular junctions. BoNT type B (BoNT/B) most often induces mild forms of botulism with predominant dysautonomic symptoms. In food borne botulism and botulism by intestinal colonisation such as infant botulism, which are the most frequent naturally acquired forms of botulism, the digestive tract is the main entry route of BoNTs into the organism. We previously showed that BoNT/B translocates through mouse intestinal barrier by an endocytosis-dependent mechanism and subsequently targets neuronal cells, mainly cholinergic neurons, in the intestinal mucosa and musculosa. Here, we investigated the entry pathway of BoNT/B using fluorescent C-terminal domain of the heavy chain (HcB), which is involved in the binding to specific receptor(s) and entry process into target cells. While the combination of gangliosides GD_1a /GD_1b /GT_1b and synaptotagmin I and to a greater extent synaptotagmin II constitutes the functional HcB receptor on NG108-15 neuronal cells, HcB only uses the gangliosides GD_1a /GD_1b /GT_1b to efficiently bind to m-IC_cl2 intestinal cells. HcB enters both cell types by a dynamin-dependent endocytosis, which is efficiently prevented by Dynasore, a dynamin inhibitor, and reaches a common early endosomal compartment labeled by early endosome antigen (EEA1). In contrast to neuronal cells, HcB uses a Cdc42-dependent pathway to enter intestinal cells. Then, HcB is transported to late endosomes in neuronal cells, whereas it exploits a nonacidified pathway from apical to basal lateral side of m-IC_cl2 cells supporting a transcytotic route in epithelial intestinal cells.

Characterization of Clostridium Baratii Type F Strains Responsible for an Outbreak of Botulism Linked to Beef Meat Consumption in France

Introduction:

A second botulism outbreak due to Clostridium baratii occurred in France in August 2015 and included three patients who had their meal in a restaurant the same day. We report the characterization of C. baratii isolates including whole genome sequencing (WGS).

Methods:

Four C. baratii isolates collected in August 2015 from the outbreak 2 were analysed for toxin production and typing as well as for genetic characterization. WGS was done using using the NEBNext Ultra DNA Library Prep kit for Illumina (New England Biolabs) and sequenced on MiSeq machine (Illumina) in paired-end reads of 250 bases. The phylogenetic tree was generated based on the UPGMA method with genetic distances computed by using the Kimura two-parameter model. Evolutionary analyses were conducted in Bionumerics (V.6.6 Applied Maths).

Results:

Three C. baratii isolates for patient's stools and one isolate from meat produced botulinum neurotoxin (BoNT) type F and retained a bont/F7 gene in OrfX cluster. All isolates were identical according to the WGS. However, phylogeny of the core genome showed that the four C. baratii strains were distantly related to that of the previous C. baratii outbreak in France in 2014 and from the other C. baratii strains reported in databanks.

Discussion:

The fact that the strains isolated from the patients and meat samples were genetically identical supports that the meat used for the Bolognese sauce was responsible for this second botulism outbreak in France. These isolates were unrelated to that from the first C. baratii outbreak in France in 2014 indicating a distinct source of contamination. WGS provided robust determination of genetic relatedness and information regarding BoNT typing and toxin gene locus genomic localization.

Flaccid paralysis in an infant associated with a dirty wound and application of honey

An infant, who was born preterm at 36 weeks, presented with fever and ulcer at umbilical region which progressed to necrotising fasciitis of anterior abdominal wall. He was treated with intravenous penicillin, intravenous cloxacillin and local application of medicated honey. Subsequently, he required wound debridement. Postoperatively, he required prolonged invasive ventilation due to poor respiratory effort which was associated with hypotonia and areflexia. Nerve conduction study revealed absent responses. The diagnosis of infant botulism was made based on the clinical presentation, nerve conduction study and his clinical progress. Botulinum immunoglobulin was not available. He was treated with intravenous immunoglobulin and oral pyridostigmine. He was successfully extubated after 37 days, and currently the patient is doing well.

Meat Safety—I Foodborne Pathogens and Other Biological Issues

This chapter presents information pertinent to foodborne pathogens (bacteria and bacterial toxins, viruses, parasites) and other biological issues (prions) with importance to the safety of meat and meat products. Aspects covered refer mainly to the characteristics of the most important pathogenic organisms, their distribution in the environment, their transmission routes to humans, as well as their epidemiology and association with sporadic or epidemic foodborne illness. Current and emerging challenges to meat safety management also are discussed.

A penicillin- and metronidazole-resistant Clostridium botulinum strain responsible for an infant botulism case

The clinical course of a case of infant botulism was characterized by several relapses despite therapy with amoxicillin and metronidazole. Botulism was confirmed by identification of botulinum toxin and Clostridium botulinum in stools. A C. botulinum A2 strain resistant to penicillins and with heterogeneous resistance to metronidazole was isolated from stool samples up to 110 days after onset. Antibiotic susceptibility was tested by disc agar diffusion and MICs were determined by Etest. Whole genome sequencing allowed detection of a gene cluster composed of blaCBP for a novel penicillinase, blaI for a regulator, and blaR1 for a membrane-bound penicillin receptor in the chromosome of the C. botulinum isolate. The purified recombinant penicillinase was assayed. Resistance to β-lactams was in agreement with the kinetic parameters of the enzyme. In addition, the β-lactamase gene cluster was found in three C. botulinum genomes in databanks and in two of 62 genomes of our collection, all the strains belonging to group I C. botulinum. This is the first report of a C. botulinum isolate resistant to penicillins. This stresses the importance of antibiotic susceptibility testing for adequate therapy of botulism.

Characterizing the fecal microbiota of infants with botulism

BACKGROUND

Infant botulism is the most prevalent form of botulism in the USA, representing 68.5 % of cases reported from 2001-2012. Infant botulism results when botulinum toxin-producing clostridia (BTPC) colonize the infant gut with concomitant in vivo production of the highly potent botulinum neurotoxin (BoNT). The gut microbiota of infants with botulism is largely uncharacterized; therefore, it remains unclear whether the microbiota profile of these patients are distinct in composition, abundance, or diversity. To address this uncertainty, we employed 16S rRNA gene profiling to characterize the fecal microbiota in 14 stool samples among laboratory-confirmed and non-confirmed infant botulism cases.

RESULTS

Seven bacterial phyla were identified among all 14 infant stool samples examined. Compared to samples from non-confirmed cases, the fecal microbiota of infant botulism patients displayed significantly higher Proteobacteria abundance. Of the 20 bacterial families identified, Enterobacteriaceae was significantly more abundant in samples from infants with botulism. Firmicutes abundance and the abundance ratio of Firmicutes/Proteobacteria was significantly lower in samples from infants with botulism. Lactobacillus spp. abundance was notably reduced in 12 of the 14 samples. Clostridium botulinum and Clostridium baratii were identified in low relative abundances in confirmed and non-confirmed samples based on their 16S rRNA gene profiles, although their toxigenicity remained undetermined. No significant differences were observed in the number of operational taxonomic units (OTUs) observed or in fecal microbiota diversity between laboratory-confirmed and non-confirmed samples. Correlations between individual phylum abundances and infant age were variable, and no significant differences were shown in number of OTUs observed or in fecal microbiota diversity between samples delineated by overall mean age.

CONCLUSIONS

Significant differences in Proteobacteria, Firmicutes, and Enterobacteriaceae abundances were identified in the fecal microbiota of infants with botulism when compared to samples from non-confirmed cases. Fecal microbiota diversity was not significantly altered in infants with botulism, and a limited presence of BTPC was shown. It could not be determined whether the fecal microbiota profiles shown here were comparable prior to patient illness, or whether they were the direct result of infant botulism. The results of this study do, however, provide a detailed and descriptive observation into the infant gut microbiota after intestinal colonization by BTPC.

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.

Morphological and genetic characterization of group I Clostridium botulinum type B strain 111 and the transcriptional regulator spoIIID gene knockout mutant in sporulation

Clostridium botulinum is a heat-resistant spore-forming bacterium that causes the serious paralytic illness botulism. Heat-resistant spores may cause food sanitation hazards and sporulation plays a central role in the survival of C. botulinum. We observed morphological changes and investigated the role of the transcriptional regulator SpoIIID in the sporulation of C. botulinum type B strain 111 in order to elucidate the molecular mechanism in C. botulinum. C. botulinum type B formed heat-resistant spores through successive morphological changes corresponding to those of Bacillus subtilis, a spore-forming model organism. An analysis of the spoIIID gene knockout mutant revealed that the transcriptional regulator SpoIIID contributed to heat-resistant spore formation by C. botulinum type B and activated the transcription of the sigK gene later during sporulation. Transcription of the spoIIID gene, which differed from that in B. subtilis and Clostridium difficile, was observed in the sigE gene knockout mutant of C. botulinum type B. An analysis of the sigF gene knockout mutant showed that the sporulation-specific sigma factor SigF was essential for transcription of the spoIIID gene in C. botulinum type B. These results suggest that the regulation of sporulation in C. botulinum is not similar to that in B. subtilis and other clostridia.

Infant botulism

Infant botulism is a rare condition caused by intestinal colonization with Clostridium botulinum. The enteric toxin causes intestinal immobility and progressive descending paralysis due to the effect on acetylcholine release at the neuromuscular junction and other cholinergic nerve terminals, particularly in the gut. Herein, we report an infant with infantile botulism because of rare clinically entity, with early diagnosis and appropriate treatment recover no squeal.

Infant botulism due toC. butyricumtype E toxin: a novel environmental association with pet terrapins

We describe two cases of infant botulism due toClostridium butyricumproducing botulinum type E neurotoxin (BoNT/E) and a previously unreported environmental source. The infants presented at age 11 days with poor feeding and lethargy, hypotonia, dilated pupils and absent reflexes. Faecal samples were positive forC. butyricumBoNT/E. The infants recovered after treatment including botulism immune globulin intravenous (BIG-IV).C. butyricumBoNT/E was isolated from water from tanks housing pet ‘yellow-bellied’ terrapins (Trachemys scripta scripta): in case A the terrapins were in the infant's home; in case B a relative fed the terrapin prior to holding and feeding the infant when both visited another relative.C. butyricumisolates from the infants and the respective terrapin tank waters were indistinguishable by molecular typing. Review of a case ofC. butyricumBoNT/E botulism in the UK found that there was a pet terrapin where the infant was living. It is concluded that theC. butyricum-producing BoNT type E in these cases of infant botulism most likely originated from pet terrapins. These findings reinforce public health advice that reptiles, including terrapins, are not suitable pets for children aged <5 years, and highlight the importance of hand washing after handling these pets.

Complete nucleotide sequence of a plasmid containing the botulinum neurotoxin gene in Clostridium botulinum type B strain 111 isolated from an infant patient in Japan

Botulinum neurotoxins (BoNTs) are highly potent toxins that are produced by Clostridium botulinum. We determined the complete nucleotide sequence of a plasmid containing the botulinum neurotoxin gene in C. botulinum type B strain 111 in order to obtain an insight into the toxigenicity and evolution of the bont gene in C. botulinum. Group I C. botulinum type B strain 111 was isolated from the first case of infant botulism in Japan in 1995. In previous studies, botulinum neurotoxin subtype B2 (BoNT/B2) produced by strain 111 exhibited different antigenic properties from those of authentic BoNT/B1 produced by strain Okra. We have recently shown that the isolates of strain 111 that lost toxigenicity were cured of the plasmid containing the bont/B2 gene. In the present study, the plasmid (named pCB111) was circular 265,575 bp double-stranded DNA and contained 332 predicted open reading frames (ORFs). 85 gene products of these ORFs could be functionally assigned on the basis of sequence homology to known proteins. The bont/B2 complex genes were located on pCB111 and some gene products may be involved in the conjugative plasmid transfer and horizontal transfer of bont genes. pCB111 was similar to previously identified plasmids containing bont/B1, /B5, or/A3 complex genes in other group I C. botulinum strains. It was suggested that these plasmids had been derived from a common ancestor and had played important roles for the bont gene transfer between C. botulinum.

Infant botulism in Andalusia (Southern Spain)

BACKGROUND

Infant botulism (IB) is caused by the intestinal colonization by Clostridium botulinum in the first year of life and its subsequent production of neurotoxins. Traditionally, IB has been associated to honey consumption. IB cases tend to cluster in geographic regions. In Europe, IB is a rare disorder. From 1976 through 2006, 65 cases were identified in 13 European countries. In Spain, in the last 15 years, most of the cases have been reported in one region, Andalusia (Southern Spain). A specific treatment for IB type A and type B (BabyBIG) is available outside of the United States since 2005.

METHODS

and aims: We performed a retrospective review of IB cases detected in Andalusia since 1997 and compare them with the cases of IB reported in Europe.

RESULTS

We identified 11 confirmed cases of IB in Andalusia since 1997, and 14 cases in Spain. Nine out of 11 cases were detected since 2007; none of these infants had been exposed to honey consumption. One case in 1997 and another in 2000 were associated to honey. Two cases were treated with BabyBIG in 2007. In the period 2006-2012 the cases of IB reported in Europe were 54.

CONCLUSIONS

We identified a considerable increase in the incidence of IB since 2006. A tendency to a reduction in the number of cases of IB linked to honey consumption has also been identified. An increase in the exposure to these bacteria from the environment could be presumed. Clinicians should maintain a high index of suspicion for this treatable disorder.

Detection of C. botulinum types in honey by mPCR

The aim of this study was to determine the prevalence of Clostridium botulinum in honey samples using conventional methods and multiplex PCR (mPCR). A total number of 150 honey samples were randomly collected from apiaries, retail shops, weekly open bazaars, and supermarkets in Samsun, Turkey. Of 150 honey samples, 4 (2.6%) were positive for the botulinum neurotoxin gene by mPCR analysis. A total of 4 C. botulinum isolates were obtained from the mPCR positive samples, of which 3 were type A and 1 was type B. No samples were positive regarding the type E and type F neurotoxin genes. This is the first report of type A and type B spores of C. botulinum being detected and isolated in Turkey. This study revealed that some honey samples may present a potential hazard for food borne and infant botulism.

Infant botulism and indications for administration of botulism immune globulin

Infant botulism is caused by the ingestion of Clostridium botulinum spores and leads to a life-threatening descending motor weakness and flaccid paralysis in infant children. This disease presents with symptoms such as constipation, weakness, and hypotonia and can lead to respiratory failure. Botulism immune globulin (BIG) was created to treat this deadly disease and functions by neutralizing all systemically circulating botulism toxins. It is indicated in children with clinically diagnosed infant botulism, before diagnostic confirmation, and has been shown to lead to a significant reduction in intensive care unit and hospital stay for these patients. This review article discusses the epidemiology, clinical presentation, history of BIG, and indications for administration of BIG.

Draft Genome Sequence of Clostridium botulinum Type B Strain Osaka05, Isolated from an Infant Patient with Botulism in Japan

Clostridium botulinum strain Osaka05, which has been isolated from an infant patient with botulism in Japan, is the first strain producing botulinum neurotoxin subtype B6. Here, we report the draft genome sequence of C. botulinum Osaka05.

Persistent neurogenic bladder dysfunction due to infantile botulism

We present a child, 5 months of age, diagnosed with infantile botulism, showing the signs of neurogenic bladder dysfunction. The patient presented with progressive muscle weakness, hypotonia, suckling and swallowing problems and absent peripheral reflexes at clinical examination. Botulinum neurotoxin type A was detected in her serum, confirming the diagnosis. Starting at day 6, the girl presented with a urinary retention initially necessitating free bladder drainage and subsequently intermittent catheterisation. After 6 weeks in intensive care, the patient recovered but the bladder underactivity persisted. Four months following recovery, a urodynamic evaluation was performed, showing a near normal detrusor activity and normal bladder emptying, and the catheterisation was ceased. At 6 months, the girl was diagnosed with a urinary tract infection and bladder emptying problems, which persisted, and clean intermittent catheterisation was started. The final urodynamic evaluation, a year and a half after her initial presentation, revealed a normal detrusor activity and an adequate bladder emptying.

What next for botulism vaccine development?

Botulism is a severe neuroparalytic disease caused by the toxins produced from several Clostridium species. Botulinum neurotoxins (BoNTs) cause flaccid paralysis by inducing a blockade at voluntary motor and autonomic cholinergic junctions that, if not treated, can be fatal. Vaccination to elicit protective circulating antibodies that bind, neutralize and clear toxins before they can be internalized and affect cholinergic neurons remains the most effective form of protection against BoNT. A pentavalent BoNT toxoid vaccine administered in the USA under an Investigational New Drug protocol to at-risk workers was discontinued by the CDC in 2011 due to diminished potency and reactogenic effects. Subsequent research efforts have primarily focused on recombinant protein antigens. This review focuses on the development of a recombinant bivalent vaccine (rBV A/B) composed of purified recombinant BoNT/A and BoNT/B receptor-binding domain proteins, as well as presenting a summary of progress and issues associated with alternative vaccines currently being developed against botulism.

High sensitivity ELISA for detection of botulinum neurotoxin serotype F

Botulinum neurotoxins (BoNTs) are classified as category A biological threat agents by the Centers for Disease Control and Prevention (CDC) in the United States for its hazardous and potential bioterrorist threat to the public. About 1% naturally occurring botulisms are caused by Botulinum neurotoxin serotype F (BoNT/F). Most of the immunoassays for detecting BoNTs focus on the serotypes A and B, but few methods have been established for the detection of BoNT/F. Recently, the recombinant Hc subunit of botulinum neurotoxin type F (rFHc) was expressed as an effective vaccine against BoNT/F, indicating that this rFHc could be an effective immunogen to raise monoclonal antibodies (MAbs) for the detection and neutralization of BoNT/F. Here we present a novel sandwich enzyme-linked immunosorbent assay (ELISA) based on two MAbs against rFHc, which were FMMU-BTF-8 and FMMU-BTF-29 as capture antibody and detection antibody, respectively. The limit of detection (LOD) of this ELISA reached 12.09 pg/mL, much less than that of the other reported immunoassays. A simple, sensitive ELISA for detecting and quantifying BoNT/F was established, which can be used as a valuable method to detect and quantify BoNT/F.

Equine botulinum antitoxin for the treatment of infant botulism

Infant botulism is the most common form of human botulism in Argentina and the United States. BabyBIG (botulism immune globulin intravenous [human]) is the antitoxin of choice for specific treatment of infant botulism in the United States. However, its high cost limits its use in many countries. We report here the effectiveness and safety of equine botulinum antitoxin (EqBA) as an alternative treatment. We conducted an analytical, observational, retrospective, and longitudinal study on cases of infant botulism registered in Mendoza, Argentina, from 1993 to 2007. We analyzed 92 medical records of laboratory-confirmed cases and evaluated the safety and efficacy of treatment with EqBA. Forty-nine laboratory-confirmed cases of infant botulism demanding admission in intensive care units and mechanical ventilation included 31 treated with EqBA within the 5 days after the onset of signs and 18 untreated with EqBA. EqBA-treated patients had a reduction in the mean length of hospital stay of 23.9 days (P = 0.0007). For infants treated with EqBA, the intensive care unit stay was shortened by 11.2 days (P = 0.0036), mechanical ventilation was reduced by 11.1 days (P = 0.0155), and tube feeding was reduced by 24.4 days (P = 0.0001). The incidence of sepsis in EqBA-treated patients was 47.3% lower (P = 0.0017) than in the untreated ones. Neither sequelae nor adverse effects attributable to EqBA were noticed, except for one infant who developed a transient erythematous rash. These results suggest that prompt treatment of infant botulism with EqBA is safe and effective and that EqBA could be considered an alternative specific treatment for infant botulism when BabyBIG is not available.

The osmolyte trimethylamine N-oxide (TMAO) increases the proteolytic activity of botulinum neurotoxin light chains A, B, and E: implications for enhancing analytical assay sensitivity

Botulism, the disease caused by botulinum neurotoxins (BoNTs), secreted by the spore-forming, anaerobic bacteria Clostridium botulinum, has been associated with food poisoning for centuries. In addition, the potency of BoNTs coupled with the current political climate has produced a threat of intentional, malicious poisoning by these toxins. The ability to detect and measure BoNTs in complex matrixes is among the highest research priorities. However, the extreme potency of these toxins necessitates that assays be capable of detecting miniscule quantities of these proteins. Thus, signal-boosting strategies must be employed. A popular approach uses the proteolytic activity of the BoNT light chain (LC) to catalyze the cleavage of synthetic substrates; reaction products are then analyzed by the analytical platform of choice. However, BoNT LCs are poor catalysts. In this study, the authors used the osmolyte trimethylamine N-oxide (TMAO) to increase the proteolytic activities of BoNT LCs. Their data suggest that concentrated solutions of TMAO induce complete folding of the LCs, resulting in increased substrate affinity and enhanced enzyme turnover. The authors observed increases in catalysis for BoNT serotypes A, B, and E, and this increased proteolytic activity translated into substantial increases in analytical assay sensitivity for these medically relevant toxins.

Characterization of the epitope region of F1-2 and F1-5, two monoclonal antibodies to Botulinum neurotoxin type A

F1-2 and F1-5 are mouse IgG1 monoclonal antibodies that bind the heavy chain of Botulinum neurotoxin serotype A (BoNT/A). To characterize the epitopes of F1-2 and F1-5, three complementary experimental approaches were selected. First, recombinant peptide fragments of BoNT/A heavy-chain were used in Western blots to identify the epitope regions. Second, a peptide phage display library was used to identify specific amino acids bound by F1-2 and F1-5, and these amino acids were mapped onto the three-dimensional structure of BoNT/A. Third, selected amino acids were mutated to alanine and the effects of the mutations on F1-2 and F1-5 binding were evaluated. Data from recombinant peptide fragment binding experiments suggested that the epitopes for antibodies F1-2 and F1-5 are located between amino acids R564 and S793 on the toxin heavy chain. Furthermore, elimination of amino acids from the amino terminus (R564-K595), or from the carboxyl terminus (N759-S793) of this fragment abolished binding of both F1-2 and F1-5, suggesting a conformational epitope for these antibodies. Peptide sequences deduced from antibody binding to the peptide phage display library suggested that tyrosine residues located at positions 748, 750, and 753 might form a significant part of the F1-2 and F1-5 epitope motif. Mutation of Y750 or Y753 to alanine significantly reduced binding of either antibody, while mutation of Y748 to alanine had no effect on antibody binding. The nucleotide and deduced amino acid sequences of the variable regions of the heavy chains of F1-2 and F1-5 are reported. The complementarity determining regions (CDRs) of the heavy chains were found to be 78% identical. It is possible that F1-2 and F1-5 bind the same epitope via the common amino acids within their CDRs.

Development of cell-based assays to measure botulinum neurotoxin serotype A activity using cleavage-sensitive antibodies

Botulinum neurotoxins (BoNTs) are zinc-metalloproteases that cleave components of the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein complex, inhibiting acetylcholine release into neuromuscular junctions, resulting in flaccid paralysis and eventual death. The potential for the malicious misuse of these toxins as bioweapons has created an urgent need to develop effective therapeutic countermeasures. Robust cell-based assays will be essential for lead identification and the optimization of therapeutic candidates. In this study, the authors developed novel BoNT serotype A (BoNT/A) cleavage-sensitive (BACS) antibodies that only interact with full-length SNAP-25 (synaptosomal-associated protein of 25 kDa), the molecular target of the BoNT/A serotype. These antibodies exhibit high specificity for full-length SNAP-25, allowing the BoNT/A-mediated proteolysis of this protein to be measured in diverse assay formats, including several variations of enzyme-linked immunosorbent assay and multiple immunofluorescence methods. Assays built around the BACS antibodies displayed excellent sensitivity, had excellent reproducibility, and were amenable to multiwell formats. Importantly, these assays provided novel methods for evaluating BoNT/A activity in cellular models of intoxication and allowed for the high-throughput evaluation of experimental compounds.

Report of two unlinked cases of infant botulism in the UK in October 2007

Infant botulism is a rare disease in the UK, with the first case being recognized in 1978 and only five subsequent cases being reported before 2007. This study reports two unlinked cases of infant botulism, caused by two distinct strains of Clostridium botulinum (toxin types A and B, respectively), that occurred within a single month in the south-east of England in October 2007. The use of real-time PCR to detect C. botulinum neurotoxin genes in clinical specimens to improve the diagnostic procedure and to follow carriage of the causative organism in the infant gut is described. The laboratory investigation of these two cases demonstrated that a combination of the mouse bioassay, real-time PCR assays and conventional microbiological culture can provide rapid confirmation of a clinical diagnosis and affect patient management. Both infants (aged 4 and 8 months) were previously healthy prior to the onset of symptoms, and in both cases, a diagnosis of infant botulism was delayed for at least 10 days after initial admission to hospital. Once diagnosed, one of the infants was the first in the UK to be treated with human-derived botulism immunoglobulin. Real-time PCR was used to demonstrate that C. botulinum was excreted in the infants' faeces for up to 68 and 81 days, respectively. Despite the infrequency of infant botulism in the UK, clinicians should be aware of this rare but serious condition and should seek microbiological advice when presented with young infants with compatible symptomologies.

Infant botulism mimicking Hirschprung's disease

We report a case of infant botulism presenting as primary colonic ileus--mimicking Hirschprung's megacolon. Infant botulism should be considered in any infant with constipation and neurologic abnormalities.

[Fifteen cases of food-borne botulism in Morocco: significant diagnostic contribution of electrodiagnosis]

INTRODUCTION

Botulism is a rare but serious disease, which affects the peripheral autonomous nervous system, potentially with a fatal outcome. In Morocco, botulism is exceptional.

PATIENTS AND METHOD

This was a prospective analysis of the epidemiological, clinical, neurophysiological and toxicological features of 15 cases of food-borne botulism identified among a series of 45 highly suspect cases collected in Morocco during an epidemic in August1999.

RESULTS

The 15 patients (eight females, seven males) included in the protocol were aged 3 to 49 years (average 18.8 years). One-third of the cases occurred in a familial context. The clinical presentation was typical and complete in nine cases; respiratory failure was noted in four patients. Botulinum toxins were found in nine cases. Outcome was less than favorable, with total recovery in seven cases, persistence of motor sequelae in three and death in five. Electrophysiological investigations showed an incrementing response at high frequency in 73.3%, a decrement at lower frequency in 60% and low motor amplitudes in 93%. These findings constituted a very sensitive and specific triad for botulism diagnosis.

DISCUSSION/CONCLUSION

These findings illustrate the gravity of botulism and the important diagnostic value of neurophysiological results, especially incrementation, which can provide a very pertinent diagnostic contribution, especially in seronegative patients.

Genetic characterization of Clostridium botulinum associated with type B infant botulism in Japan

The 15 proteolytic Clostridium botulinum type B strains, including 3 isolates associated with infant botulism in Japan, were genetically characterized by phylogenetic analysis of boNT/B gene sequences, genotyping, and determination of the boNT/B gene location by using pulsed-field gel electrophoresis (PFGE) for molecular epidemiological analysis of infant botulism in Japan. Strain Osaka05, isolated from a case in 2005, showed a unique boNT/B gene sequence and was considered to be a new BoNT/B subtype by phylogenetic analysis. Strain Osaka06, isolated from a case in 2006, was classified as the B2 subtype, the same as strain 111, isolated from a case in 1995. The five isolates associated with infant botulism in the United States were classified into the B1 subtype. Isolates from food samples in Japan were divided into the B1 and the B2 subtypes, although no relation with infant botulism was shown by PFGE genotyping. The results of PFGE and Southern blot hybridization with undigested DNA suggested that the boNT/B gene is located on large plasmids (approximately 150 kbp, 260 kbp, 275 kbp, or 280 kbp) in five strains belonging to three BoNT/B subtypes from various sources. The botulinum neurotoxin (BoNT) of Osaka05 was suggested to have an antigenicity different from the antigenicities of BoNT/B1 and BoNT/B2 by a sandwich enzyme-linked immunosorbent assay with the recombinant BoNT/B-C-terminal domain. We established a multiplex PCR assay for BoNT/B subtyping which will be useful for epidemiological studies of type B strains and the infectious diseases that they cause.

Infant botulism: two recent cases and literature review

Infant botulism is a cause for significant pediatric morbidity in the United States, though early recognition and supportive care can greatly improve clinical outcomes. Since the approval of human botulism immune globulin by the United States Food and Drug Administration (FDA) for the treatment of infant botulism in 2003, the importance of prompt initiation of therapy has been emphasized, with clinical suspicion remaining the mainstay of diagnosis. In this report, 2 cases of infant botulism are described. Each presented to the Pediatric Neurology service at our institution in Upstate New York in the spring and summer months of 2007 and were felt to be related to markedly dusty environmental conditions and the probable ingestion of C. botulinum organisms present in soil. Following this, a comprehensive review of the literature regarding infant botulism in the United States is presented, wherein the pathophysiology, clinical features, epidemiology, and treatment are discussed.

Infant botulism type Ba: first culture-confirmed case in the United Arab Emirates

We report on a 3-month-old girl with culture-confirmed infant botulism caused by a rare double toxin-producing Clostridium botulinum type Ba. This case was not related to honey-feeding. The clinical course was prolonged, with minimal spontaneous improvement at onset, and a period of fluctuating motor weakness and nasogastric feeding dependence afterward. Neurophysiologic studies produced normal results. Human botulism immune globulin was administered empirically on day 23 of presentation, with rapid full recovery. This case highlights the importance of pursuing diagnoses of infant botulism despite normal results of neurophysiologic testing and no history of honey-feeding. Our case also demonstrates a favorable response to human botulism immune globulin, despite the relatively late treatment.

Botulism: cause, effects, diagnosis, clinical and laboratory identification, and treatment modalities

Botulism is a neuroparalytic disease caused by neurotoxins produced by the bacteria Clostridium botulinum. Botulinum neurotoxins (BoNTs) are among the most potent naturally occurring toxins and are a category A biological threat agent. The 7 toxin serotypes of BoNTs (serotypes A-G) have different toxicities, act through 3 different intracellular protein targets, and exhibit different durations of effect. Botulism may follow ingestion of food contaminated with BoNT, from toxin production of C botulinum present in the intestine or wounds, or from inhalation of aerosolized toxin. Intoxication classically presents as an acute, symmetrical, descending flaccid paralysis. Early diagnosis is important because antitoxin therapy is most effective when administered early. Confirmatory testing of botulism with BoNT assays or C botulinum cultures is time-consuming, and may be insensitive in the diagnosis of inhalational botulism and in as many as 32% of food-borne botulism cases. Therefore, the decision to initiate botulinum antitoxin therapy is primarily based on symptoms and physical examination findings that are consistent with botulism, with support of epidemiological history and electrophysiological testing. Modern clinical practice and antitoxin treatment has reduced botulism mortality rates from approximately 60% to < or =10%. The pentavalent botulinum toxoid is an investigational product and has been used for more than 45 years in at-risk laboratory workers to protect against toxin serotypes A to E. Due to declining immunogenicity and potency of the pentavalent botulinum toxoid, novel vaccine candidates are being developed.