Foodborne Botulism
Introduction
Briefly introduce your topic
Clostridium botulinum
See also Clostridium botulinum
Clostridium botulinum is a gram-positive, anaerobic, rod-shaped bacterium that produces the botulinum neurotoxin, which is the cause of foodborne botulism. The bacteria lie dormant as spores until exposed to ideal environmental conditions that enable them to germinate, in which the neurotoxin is then produced. These spores are also very resistant to adverse environmental conditions so eradication of them is difficult. Proliferation of these spores occurs if conditions include for "group I" (discussed below) optimal temperatures between 35-40°C and a pH of 4.6, while "group II" requires the temperature to be between 18-25°C and a pH of 5.0, with both groups requiring anaerobic conditions [1].
Classification
There are four distinct groups (designated I-IV) in which C. botulinum 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.
| Characteristics | Group I | Group II |
|---|---|---|
| Neurotoxin types | A, B, F | B, E, F |
| Human Disease | Yes | Yes |
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
| 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
Foodborne Botulism
Signs & Symptoms
Foodborne Botulism in the United States
Treatment
Diagnosis
Often physicians may mistake a diagnosis of botulism to be other diseases such as Guillain-Barre syndrome, stroke or myasthenia gravis. In such a case, steps are needed to be taken in order to diagnose Clostridium Botulinum by brain scans, spinal fluid examination, electromyography or a tensilon test in order to rule out the other diseases. To directly diagnose whether a microorganism exists within the patient, the doctor will isolate the toxin by the stool and inject it into the mice. When the mice show symptoms of botulinum, then the patient is notified that he/she has a bacteria living inside of them.
Treatment
Treatment of foodborne botulism varies depending on the method the microorganism got into the system to the amount of time it was in the system. The following are methods that physicians may use in order to treat a patient. In cases that the doctor needs an antitoxin, they are able to contact the state health officials or CDC for them.
- If diagnosed early, the foodborne and wound botulism can be treated with equine antitoxin in order to the block the toxin to circulate in the blood. This can occur for several weeks as the patient
- If the patient is diagnosed late, and has respiratory failure and paralysis the patient will need to be on a breathing ventilator and intensive care for several weeks until the doctor approves that the patient is fine
- If the botulism was foodborne, it is possible that the doctor will induce vomiting or use enema in order to remove the contaminated food
- If the botulism is by a wound, the doctor my treat by removing the toxin producing bacteria by antibiotics.
Prevention
How to Stop Foodborne Diseases in Home-Canning
In efforts to prevent foodborne botulinum from increasing its prevalency in America, the USDA implemented a guide to home canning. In this guide, it shows methods of “selecting, preparing and canning” of fruits, vegetables, meats, jams and jellies.
In generalities, home canned foods should be done with the following conditions:
- Be sure that the jar going to be used was washed in hot water with detergent.
- Store the jars at around 50-70 degrees Fahrenheit
- If possible, try the method of “hot packing” which removes most of the oxygen from the food
- Acidity: the acidity of the canned food can determine whether the botulinum spore lives or not. At high pH levels, botulinum would not be able to grow since the conditions are not ideal.
- Low-acid (pH >4.6). These should be sterilized at temperatures of 240-250 degrees Fahrenheit in order to ensure that the microorganism is destroyed.
- Good acidic level (pH<4.6)
Summary
Incorporate here or in Prevention section
References
1. Montville, T. J., & Mathews, K. (2005). Food Microbiology: an introduction (p. 192-193). Washington, DC: ASM Press
2. Hatheway, C. L. (1990, January). Toxigenic Clostridia (Electronic version). Clinical Microbiology Reviews, 3, 71-74.
3. McLauchlin, J., Grant, K.A., & Little, C.L. (2006, August). Food-borne botulsim in the United Kingdom (Electronic version). Journal of Public Health, 28, 339 (Table 2).
4. Montville, T. J., & Mathews, K. (2005). Food Microbiology: an introduction, (pp. 12). Washington, DC: ASM Press
5. Montville, T. J., & Mathews, K. (2005). Food Microbiology: an introduction, (pp. 33). Washington, DC: ASM Press
6. Data obtained from http://www.ncbi.nlm.nih.gov/sites/entrez?db=genomeprj&cmd=DetailsSearch&term=txid1491%5Borgn%5D+AND+pt_default%5Bprop%5D&log$=activityDownload this as a file
Edited by Carolina Ceballos, Cristina Flores, Nancy Gomez, Malisa Tov, students of Rachel Larsen
