Foodborne Botulism: Difference between revisions

Revision as of 03:52, 27 August 2009

Introduction

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Clostridium botulinum

Classification

There are four distinct groups (designated I-IV) in which C. botulism is categorized, and is solely determined by the characteristic of botulinum neurotoxin production. Furthermore, the botulinum neurotoxins can be divided into seven antigenically distinct types, A–G, and are some of the most potent toxins known [2]. Foodborne botulism is almost always associated with groups I and II, with these groups producing the toxin types A, B, E and F. Toxin types A and B are the most common causes of foodborne botulism while type F is the least common.

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Interaction with Food

The interaction between food and a microbial population creates a complex microenvironment, as the presence of a bacteria on food will directly affect the overall food ecosystem. Although C. botulism is an obligate anaerobe, foods that are aerobic can still become contaminated by this bacteria and are often the source of food poisoning outbreaks. For example, C. botulinum growth in potatoes, cole slaw, and sautéed onions, has caused botulism outbreaks since the oxygen in these foods leaves during cooking and although it diffuses back, it does so so slowly that most of the food product remains anaerobic [4]. Heat resistance of spores can vary greatly among the different species and even among strains. Since group I C. botulinum type A and B strains produce extremely heat-resistant spores, they therefore are the most important subtype for the public health safety of canned foods to be cautious of [5]. The only way to ensure prevention of foodborne botulism is to prevent the neurotoxin production within those foods.

Genome

Table 1: Chromosome and plasmid size and GC content of sequenced Clostridium botulinum Strains

*Source:see reference [6]*
Strain	Chromosome Size	Plasmid Size	GC content
Clostridium botulinum strain Hall A	3.8Kb	16Kb	28% for chromosome 26% for plasmid
Clostridium botulinum A str. ATCC 19397 (Los Alamos National Laboratory)	3.8 Kb	none	28% for chromosome
Clostridium botulinum A str. ATCC 3502 (Sanger Institute)	3.9Kb	0.016Kb	28 % for chromosome 26% for plasmid
Clostridium botulinum A str. Hall (Los Alamos National Laboratory)	3.7Kb	none	28% for chromosome
Clostridium botulinum A2 str. Kyoto (Los Alamos National Laboratory)	4.15Kb	none	28% for chromosome
Clostridium botulinum A3 str. Loch Maree (Los Alamos National Laboratory)	4Kb	0.27Kb	28% for chromosome 25% for plasmid
Clostridium botulinum B str. Eklund 17B (Los Alamos National Laboratory)	3.8Kb	0.048 Kb	27% for chromosome 24% for plasmid
Clostridium botulinum B1 str. Okra okra (Los Alamos National Laboratory)	3.9Kb	0.15Kb	28% for chormosome 25% for plasmid
Clostridium botulinum Ba4 str. 657 (Los Alamos National Laboratory)	3.9Kb	Plasmid pCLJ- 0.27Kb Plasmid pCLJ2-0.01Kb	28% for chromosome 25% for pCLJ plasmid 24 for pCLJ2 plasmid
Clostridium botulinum E3 str. Alaska E43 (Los Alamos National Laboratory)	3.6Kb	None	27% for chromosome
Clostridium botulinum F str. Langeland (Los Alamos National Laboratory)	4.0Kb	0.018Kb	28% for chromosome 26% for plasmid

Pathology

Virulence Genes & Factors

Mechanism