Tracking sources of Clostridium botulinum type E contamination in seal meat.

Botulism in Nunavik, Quebec is associated with the consumption of aged marine mammal meat and fat. The objective was to identify meat handling practices presenting a risk of contamination of seal meat with C. botulinum. Potential sources of contamination were assessed through interviews with igunaq producers from five communities of Nunavik. These sources were verified by detection and isolation of C. botulinum from igunaq prepared in the field from seal carcasses. Interviews indicated practices presenting a risk for contamination included: placing meat or fat on coastal rocks, using seawater for rinsing, and ageing meat in inverted seal skin pouches. Although the presence of C. botulinum type E spores was detected in only two of 32 (6.3%) meat or fat samples collected during the butchering process, two of four igunaq preparations from these samples contained type E botulinum toxin. Analysis of C. botulinum type E isolates recovered from these preparations indicated that shoreline soil may be a source of contamination. Seal meat and fat may be contaminated with C. botulinum type E during the butchering process. Measures can be adopted to reduce the risks of contamination in the field and possibly decrease the incidence of type E botulism in Nunavik.

Distribution of Clostridium botulinum type E strains in Nunavik, Northern Quebec, Canada.

The distribution and levels of Clostridium botulinum type E were determined from field sites used by Inuit hunters for butchering seals along the coast of Nunavik. The incidence rates of C. botulinum type E in shoreline soil along the coast were 0, 50, and 87.5% among samples tested for the Hudson Strait, Hudson Bay, and Ungava Bay regions, respectively. Spores were detected in seawater or coastal rock surfaces from 17.6% of butchering sites, almost all of which were located in southern Ungava Bay. Concentrations of C. botulinum type E along the Ungava Bay coast were significantly higher than on the coasts of Hudson Strait and Hudson Bay, with the highest concentrations (270 to 1,800/kg of sample) found near butchering sites located along the mouths of large rivers. The Koksoak River contained high levels of C. botulinum type E, with the highest median concentration (270/kg) found in sediments of the marine portion of the river. C. botulinum type E was found in the intestinal contents (4.4%) and skins (1.4%) of seals. A high genetic biodiversity of C. botulinum type E isolates was observed among the 21 butchering sites and their surroundings along the Nunavik coastline, with 83% of isolates (44/53) yielding distinct pulsed-field gel electrophoresis genotypes. Multiple sources of C. botulinum type E may be involved in the contamination of seal meat during butchering in this region, but the risk of contamination appears to be much higher from environmental sources along the shoreline of southern Ungava Bay and the sediments of the Koksoak River.

Analysis of Clostridium botulinum serotype E strains by using multilocus sequence typing, amplified fragment length polymorphism, variable-number tandem-repeat analysis, and botulinum neurotoxin gene sequencing.

A total of 41 Clostridium botulinum serotype E strains from different geographic regions, including Canada, Denmark, Finland, France, Greenland, Japan, and the United States, were compared by multilocus sequence typing (MLST), amplified fragment length polymorphism (AFLP) analysis, variable-number tandem-repeat (VNTR) analysis, and botulinum neurotoxin (bont) E gene sequencing. The strains, representing environmental, food-borne, and infant botulism samples collected from 1932 to 2007, were analyzed to compare serotype E strains from different geographic regions and types of botulism and to determine whether each of the strains contained the transposon-associated recombinase rarA, involved with bont/E insertion. MLST examination using 15 genes clustered the strains into several clades, with most members within a cluster sharing the same BoNT/E subtype (BoNT/E1, E2, E3, or E6). Sequencing of the bont/E gene identified two new variants (E7, E8) that showed regions of recombination with other E subtypes. The AFLP dendrogram clustered the 41 strains similarly to the MLST dendrogram. Strains that could not be differentiated by AFLP, MLST, or bont gene sequencing were further examined using three VNTR regions. Both intact and split rarA genes were amplified by PCR in each of the strains, and their identities were confirmed in 11 strains by amplicon sequencing. The findings suggest that (i) the C. botulinum serotype E strains result from the targeted insertion of the bont/E gene into genetically conserved bacteria and (ii) recombination events (not random mutations) within bont/E result in toxin variants or subtypes within strains.

Towards an international standard for detection and typing botulinum neurotoxin-producing Clostridia types A, B, E and F in food, feed and environmental samples: a European ring trial study to evaluate a real-time PCR assay.

A real-time PCR method for detection and typing of BoNT-producing Clostridia types A, B, E, and F was developed on the framework of the European Research Project "Biotracer". A primary evaluation was carried out using 104 strains and 17 clinical and food samples linked to botulism cases. Results showed 100% relative accuracy, 100% relative sensitivity, 100% relative specificity, and 100% selectivity (inclusivity on 73 strains and exclusivity on 31 strains) of the real-time PCR against the reference cultural method combined with the standard mouse bioassay. Furthermore, a ring trial study performed at four different European laboratories in Italy, France, the Netherlands, and Sweden was carried out using 47 strains, and 30 clinical and food samples linked to botulism cases. Results showed a concordance of 95.7% among the four laboratories. The reproducibility generated a relative standard deviation in the range of 2.18% to 13.61%. Considering the high level of agreement achieved between the laboratories, this real-time PCR is a suitable method for rapid detection and typing of BoNT-producing Clostridia in clinical, food and environmental samples and thus support the use of it as an international standard method.

Biodiversity of Clostridium botulinum type E associated with a large outbreak of botulism in wildlife from Lake Erie and Lake Ontario.

The genetic relatedness of Clostridium botulinum type E isolates associated with an outbreak of wildlife botulism was studied using random amplification of polymorphic DNA (RAPD). Specimens were collected from November 2000 to December 2008 during a large outbreak of botulism affecting birds and fish living in and around Lake Erie and Lake Ontario. In our present study, a total of 355 wildlife samples were tested for the presence of botulinum toxin and/or organisms. Type E botulinum toxin was detected in 110 samples from birds, 12 samples from fish, and 2 samples from mammals. Sediment samples from Lake Erie were also examined for the presence of C. botulinum. Fifteen of 17 sediment samples were positive for the presence of C. botulinum type E. Eighty-one C. botulinum isolates were obtained from plants, animals, and sediments; of these isolates, 44 C. botulinum isolates produced type E toxin, as determined by mouse bioassay, while the remaining 37 isolates were not toxic for mice. All toxin-producing isolates were typed by RAPD; that analysis showed 12 different RAPD types and multiple subtypes. Our study thus demonstrates that multiple genetically distinct strains of C. botulinum were involved in the present outbreak of wildlife botulism. We found that C. botulinum type E is present in the sediments of Lake Erie and that a large range of bird and fish species is affected.

An innovative molecular detection tool for tracking and tracing Clostridium botulinum types A, B, E, F and other botulinum neurotoxin producing Clostridia based on the GeneDisc cycler.

Rapid and specific detection of botulinum neurotoxin (BoNT) producing Clostridia is a priority for public health authorities, in case of both natural and intentional botulism outbreaks. This study reports on the evaluation of a detection system based on the GeneDisc Cycler designed for simultaneously testing the bont/A, bont/B, bont/E and bont/F genes encoding for the botulinum neurotoxins types A, B, E and F. BoNT-producing Clostridia (n = 102) and non-BoNT-producing bacteria (n = 52) isolated from clinical, food and environmental samples were tested using this macro-array and results were compared to the reference lethality test on mice. The bont genes were correctly detected in all C. botulinum type A, B, E and F strains available, as well as in toxigenic C. baratii type F and toxigenic C. butyricum type E. No cross reactivity was observed with non human-toxigenic bacteria, C. botulinum types C, D and G. The identification of the bont genotype using the macro-array was correlated to toxino-typing of the BoNTs as determined by the mouse bioassay. An "evaluation trial" of the GeneDisc array performed blind in four European laboratories with 77 BoNT-producing Clostridia as well as 10 food and clinical samples showed that the developed macro-array is specific and reliable for identifying BoNT/A-, BoNT/B-, BoNT/E- and BoNT/F-producing clostridial strains and for screening naturally contaminated food and fecal samples. The test is robust, has a low detection limit (c.a. 5 to 50 genome copies in the PCR reaction microwell) and is promising for monitoring BoNT-producing Clostridia in different kinds of samples including food and clinical samples.

First report worldwide of an infant botulism case due to Clostridium botulinum type E.

Clostridium botulinum type E has been associated with botulism in adults but never in infants. Infant botulism type E cases have been associated with neurotoxigenic strains of C. butyricum. We report the first infant botulism case due to C. botulinum type E worldwide.

Botulism and hot-smoked whitefish: a family cluster of type E botulism in France, September 2009.

A family cluster of three cases of type E botulism were identified in south-east France in September 2009. The suspected food source of infection was a vacuum packed hot-smoked whitefish of Canadian origin purchased by the family during a visit to Finland and consumed several weeks later in France on the day prior to symptom onset. No leftover fish was available to confirm this hypothesis. Vacuum packed hot-smoked whitefish has previously been associated with cases of type E botulism in multiple countries, including Finland, Germany, the United States and Israel.

First case of type E wound botulism diagnosed using real-time PCR.

Wound botulism is a growing problem among injecting drug users. The condition is often difficult to diagnose, with laboratory confirmation in only 50% of the cases. Here we present a real-time PCR-based method for the diagnosis of wound botulism caused by Clostridium botulinum. The assay includes an internal amplification control which is amplified simultaneously with the genes encoding neurotoxin types A, B, and E. This method was used to detect the first case of wound botulism in an injecting drug user in Sweden. In addition, to the best of our knowledge, this is the first reported case of wound botulism caused by C. botulinum type E.

Outbreak of clinically mild botulism type E illness from home-salted fish in patients presenting with predominantly gastrointestinal symptoms.

Five persons consumed home-salted fish and then presented with gastrointestinal symptoms to 3 hospitals; 2 of the patients had minimal cranial nerve palsies. Early serum samples obtained from all patients were negative for botulinum toxin. Remnant fish tested positive for botulinum toxin type E. In patients exposed to low doses of botulinum toxin type E, gastrointestinal symptoms may predominate.

Development of enrichment semi-nested PCR for Clostridium botulinum types A, B, E, and F and its application to Korean environmental samples.

An enrichment semi-nested PCR procedure was developed for detection of Clostridium botulinum types A, B, E, and F. It was applied to sediment samples to examine the prevalence of C. botulinum in the Korean environment. The first pair of primers for the semi-nested PCR was designed using a region shared by the types A, B, E, and F neurotoxin gene sequences, and the second round employed four nested primers complementary to the BoNT/A, /B, /E, and /F encoding genes for simultaneous detection of the four serotypes. Positive results were obtained from the PCR analysis of five of 44 sediments (11%) collected from Yeong-am Lake in Korea; all were identified as deriving from type B neurotoxin (bontb) genes. Two of the C. botulinum type B organisms were isolated, and their bontb genes sequenced. The deduced amino acid sequences of BoNT/B showed 99.5 and 99.8% identity with the amino acid sequence of accession no. AB084152. Our data suggest that semi-nested PCR is a useful tool for detecting C. botulinum in sediments, and renders it practicable to conduct environmental surveys.

Comparison of DNA fingerprinting methods for use in investigation of type E botulism outbreaks in the Canadian Arctic.

Pulsed-field gel electrophoresis (PFGE), randomly amplified polymorphic DNA (RAPD) analysis, and automated ribotyping were compared for epidemiological typing of Clostridium botulinum type E using clinical and food isolates associated with four botulism outbreaks occurring in the Canadian Arctic. All type E strains previously untypeable by PFGE, even with the use of a formaldehyde fixation step, could be typed by the addition of 50 microM thiourea to the electrophoresis running buffer. Digestion with SmaI or XhoI followed by PFGE was used to link food and clinical isolates from four different type E botulism outbreaks and differentiate them from among 39 group II strains. Strain differentiation was unsuccessful with the automated ribotyping system, producing a single characteristic EcoRI fingerprint common to all group II strains. RAPD analysis of C. botulinum group II strains was not consistently reproducible with primer OPJ-6 or OPJ-13, apparently discriminating between epidemiologically related strains. A modified PFGE protocol was judged to be the most useful method for typing epidemiologically related C. botulinum type E strains, based on its ability to type all strains reproducibly and with an adequate level of discrimination.

Prevalence and diversity of Clostridium botulinum types A, B, E and F in honey produced in the Nordic countries.

A total of 294 honey samples produced in Denmark, Norway and Sweden were studied for the presence of Clostridium botulinum types A, B, E and F by using a multiplex-PCR method. The samples consisted of honeycombs taken directly from beehives, and extracted honey representing several hives or apiaries. The prevalence of C. botulinum showed a significant variation between Denmark, Norway and Sweden, the proportions of positive samples being 26%, 10% and 2%, respectively. The major serotype detected was type B. When analysed with pulsed-field gel electrophoresis (PFGE) using restriction enzyme SacII, the 24 strains isolated produced eight different PFGE patterns. At a similarity level of 95%, four clusters were produced, three of which contained 20 of the 24 analysed strains. One of the clusters included isolates from both Denmark and Norway.

Proteolytic Clostridium botulinum type B in the gastric content of a patient with type E botulism due to whitefish eggs.

Whitefish eggs were confirmed by pulsed-field gel electrophoresis to cause type E foodborne botulism in a 54-year-old patient in Finland. Botulinum neurotoxin and/or nonproteolytic Clostridium botulinum type E organisms were detected in fecal and gastric samples from the patient and in suspected whitefish eggs. Apart from C. botulinum type E, proteolytic type B organisms were detected in the patient's gastric content. This was considered to be insignificant with respect to the clinical disease, suggesting botulinal spores to be occasionally present in the human gastrointestinal tract without any apparent clinical significance. This is the first domestic case of foodborne botulism in Finland.