Cranial-nerve palsies and vomiting

Clostridium botulinum and the safety of minimally heated, chilled foods: an emerging issue?

Foodborne botulism is caused by consumption of preformed botulinum neurotoxin, with as little as 30 ng of neurotoxin being potentially lethal. Consumption of minute quantities of neurotoxin-containing food can result in botulism. In view of the severity of foodborne botulism, it is essential that new foods be developed safely without an increase in incidence of this disease. Minimally heated, chilled foods are a relatively new type of food, sales of which are currently increasing by about 10% per annum. These products meet consumer demand for high-quality foods that require little preparation time. Their safety and quality depends on mild heat treatment, chilled storage, restricted shelf life and sometimes on intrinsic properties of the foods. The principal microbiological hazard is nonproteolytic Clostridium botulinum, and there is a concern that this may become an emerging issue. A considerable amount of research and development over the last 15 years has underpinned the safe production of commercial, minimally heated, chilled foods with respect to foodborne botulism, and it is essential that safe food continues to be developed. In particular, the desire to use lighter heat processes and a longer shelf life presents a challenge that will only be met by significant developments in quantitative microbiological food safety.

Food-borne botulism in the United Kingdom

Food-borne botulism is a rare but serious disease caused by ingestions of neurotoxin [botulinum neurotoxins (BoNTs)] produced as a result of the growth of the bacterium Clostridium botulinum in foods before consumption. The disease is rare in the United Kingdom, and only 62 cases have been recognized between 1922 and 2005. This report provides a brief review of C. botulinum and food-borne botulism as well as descriptions of the six episodes (33 cases with three deaths) of this disease that occurred in the United Kingdom between 1989 and 2005. The six incidents illustrate the importance of the risk factors of poor processing or storage of commercially prepared foods, improper home preservation of foods and travel to countries where botulism is much more common than in the United Kingdom. Even small outbreaks of food-borne botulism can precipitate a national emergency and inundate public health and acute care provision. This report provides a reminder to public health professions of the occurrence, diagnosis, treatment and control of this rare but serious food-borne disease.

Development and application of Real-Time PCR assays to detect fragments of the Clostridium botulinum types A, B, and E neurotoxin genes for investigation of human foodborne and infant botulism

Real-time PCR assays for detection of Clostridium botulinum neurotoxin (BoNT) gene fragments specific to BoNTA, B, and E were developed as alternatives to the mouse bioassay. The expected specificities of the PCR assays were demonstrated by in silico analysis as well as empirical testing of target DNA extracted from 83 pure cultures of C. botulinum, and 44 bacteria from other species. The sensitivities of the assays were found to be equivalent to 16, 10, and 141 genomes for BoNT A, B, and E, respectively. The assays were shown to be applicable to both purified DNA, as well as crude DNA extracted from cultures and enrichment broths. The assays were evaluated using DNA extracted directly from clinical and food specimens as well as from inoculated broths using material collected from seven confirmed and one suspected case of botulism. The appropriate BoNT genes were detected in material from seven of the eight cases of botulism and provided a supportive diagnosis faster than the conventional bioassay. These assays have already proven useful for pubic health microbiological investigation of suspected cases of human botulism by substantially improving the diagnostic process.

Characterization of Clostridium botulinum strains associated with an infant botulism case in the United Kingdom

The sixth case of infant botulism in the United Kingdom was reported in 2001. The case was caused by a type B strain of Clostridium botulinum. Strains of C. botulinum were isolated from the baby's feces and from foodstuffs in the household in an attempt to document transmission. The aims of this study were to characterize the strains of C. botulinum associated with the botulism case. This was performed using a variety of techniques, including C. botulinum culture phenotypic properties, neurotoxin characterization, and pulsed-field gel electrophoresis (PFGE) banding patterns. Cultures associated with this case as well as isolates from stored and historical samples were analyzed and compared. C. botulinum type B PFGE patterns from the infant and from an opened container of infant formula were indistinguishable, while the PFGE profile of a strain presumably isolated from an unopened archival container was unique. The results suggest that the unopened brand of formula was not the source for transmission of spores to the infant and that the strain was distinct from previous botulism cases in the United Kingdom. Since environmental testing was not performed, it is not possible to deduce other sources of transmission.