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 in the stationary-phase 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. Groups I and II are both directly responsible for the cause of disease in humans. The botulinum neurotoxins can also be divided into seven antigenically distinct types, A–G, and are some of the most potent toxins known [2]. Group I contains proteolytic strains (those that are able to break down proteins due to the enzymes they produce) of types B and F, while group II contains nonproteolytic strains of types B and F. 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. Type E is most commonly associated with the consumption of contaminated marine products. The most common cause of food poisoning in the United States is toxin type A, while for most of Europe the most common cause is toxin type B.
| Characteristics | Group I | Group II |
|---|---|---|
| Neurotoxin types | A, B, F | B, E, F |
| Cause of human disease | Yes | Yes |
| Proteolytic for types B and F | Yes | No |
| Disribution in the environment | Type A in the U.S. & Type B in most of Europe | Type E common in marine sites worldwide |
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
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
Foodborne botulism has occurred year after year within the United States although most people didn’t know that microorganisms may exist within food. Therefore, groups today such as the US Department of Agriculture, U.S. Food and Drug Administration, Center for Disease and Control and etcetera have formed a detailed websites full of information for the general population to view. For example, in August of 2001 the USDA had implemented a fact sheet to minimalize the out interaction with Clostridium Botulinum. In this fact sheet, the USDA clearly states that any food bought from the grocery stores that are frozen must be inspected carefully for any broken packages, or refrozen products. In such a case, there is likely possibility that a microbe may have infected the product.
In the case that a physician detects a commercial product may harm the general population; the doctor should notify the state public health. After the state public health is notified, they will then contact the CDC, USDA and the FDA. From here, there was diagnostic testing done in the laboratory to determine whether it is Clostridium Botulinum.
Today, the CDC produces reports of Foodborne diseases yearly by which anyone may be able to read. In each year, they state where the disease had occurred, and the vehicle of the disease.
More locally, the state of California has formed a Cannery Inspection Program by which implements a strict hygiene for all 200 licensed canners in the methods of canning and cleanliness. Specifically, they inspect the facilities, equipment and the level of food protection from microbes. Whenever, the facility does not reach the expected level, then the state of California will force a recall of the product until that facility meets the demands for this state.
However, the United States may attempt to minimalize the amount of cases of Clostridium Botulinum per year, it cannot be completely abolished. Even with our technologies today, in 2007 there was a canned chili sauce incident where the products contained botulinum toxin. Although all the products were recalled after the eight incidents, there was another person whom consumed the chili sauce. Overall, it is not possible to completely prevent cases of Clostridium botulinum but it can only be minimalized.
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
