An atypical outbreak of food-borne botulism due to Clostridium botulinum types B and E from ham.

An outbreak of human botulism was due to consumption of ham containing botulinum neurotoxins B and E. A Clostridium botulinum type E strain isolated from ham was assigned to a new subtype (E12) based on bont/E gene sequencing and belongs to a new multilocus sequence subtype, as analyzed by whole-genome sequencing.

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.

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.

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.

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.