Foodborne Botulism

Introduction

Foodborne botulism is a rare but sometimes deadly disease that occurs all over the world. It can range from having mild symptoms, which may be misdiagnosed or disregarded, to a more serious condition that can be lethal within a day. Botulism occurs as a direct result from exposure to, or the ingesting of, a botulinum neurotoxin; the most toxic natural substance known. Produced from the bacteria Clostridium botulinum, the neurotoxin will only proliferate under ideal environmental conditions. Foodborne botulism is typically associated with exposure to improperly canned foods and/or contaminated food products, and is a condition that adversely affects the nervous system. Diagnostic tests and treatments for this disease continue to improve as advancements in technology are made. Although foodborne botulism has not been eradicated, public awareness in the United States continues to grow along with continued efforts made to minimize occurrences of the disease.

Clostridium botulinum

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.

Table 1: Clostridium botulinum Groups I & II

*Source: see reference* [3]
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 Western U.S.; Type B in the Eastern U.S. and in most of Europe	Type E common in marine sites worldwide

Genome

Table 1: Chromosome, 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

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. botulinum 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.

Pathology

Virulence Factors

Mechanism

Signs & Symptoms

Diagnosis

Often times physicians overlook a diagnosis of botulism as being another disease or condition, such as Guillain-Barre syndrome, stroke or myasthenia gravis. In such instances, other tests may be performed to accurately diagnose Clostridium botulinum, and to rule out other condtions, by a brain scan, spinal fluid examination, electromyography or a tensilon test. To directly diagnose the existence of a microorganism within a patient, the physician will isolate the toxin from a stool sample and then inject it into mice. If the mice display symptoms of botulism, then the patient is notified and treament of the disease begins.

Treatment

This is the antitoxin that patients can be treated with. CDC

Treatment of foodborne botulism varies as it depends on the method in which the microorganism got into the body system as well as the amount of time it has been in the system. The following are methods that physicians may use in order to treat a patient. In cases where the doctor needs an antitoxin, they are able to contact the state health officials or CDC to obtain them.

If diagnosed early, the foodborne botulism can be treated with equine antitoxin in order to the block the toxin from circulating in the blood.
If diagnosed late, the patient may experience respiratory failure and paralysis and will need to be placed on a breathing ventilator and in intensive care for several weeks.
If the botulism was foodborne, it is possible that the doctor will induce vomiting or perform an enema in order to remove the contaminated food.
If the botulism is by a wound, the doctor may treat it by removing the toxin producing bacteria by antibiotics.

Foodborne Botulism in the United States

This figure shows the number of Foodborne disease outbreaks by bacteria in the year of 2006. The numbers are based on per 100,000 people.CDC: MMWR

Today, Clostridium botulinum is not well known as since many other microbes such as Salmonella continue to be a large problem. However, Foodborne botulism does occur year after year within the United States due to poor home canning and availability of information brought to the community. Groups such as the CDC, FDA and etcetera has information about Clostridium botulinum on their websites but the generally people do not realize that these microorganisms may exist since the media only portrays other microorganisms such as E. Coli and Salmonella.

Information from the FDA has shown that from 1988 to 1995, there are cases occurring yearly. Depending on the region within the United States, a different Clostridium botulinum would be more prevalent:

Type A botulinum are found mostly in the western regions
Type B spores are found mostly in the northeast and central states
Type E spores are found in the marine life in the Pacific Northwest and Great Lakes

Prevention

The occurrence of foodborne botulism in the United States has been ongoing for many years, even during a time when people did not know of the existence of microorganisms and their interaction with food products. Current organizations such as the US Department of Agriculture (USDA), U.S. Food and Drug Administration (FDA), and the Centers for Disease Control and Prevention (CDC) provide detailed information about this topic that is available to the general public. In August of 2001, the USDA implemented a fact sheet to inform the public of the food-dwelling microbes, including Clostridium botulinum, that are potentially harmful to the public given the right conditions. The CDC provides yearly reports of foodborne disease occurrences that are available to the public, including the state in which the incidence occurred and the vehicle of the disease. The increase of public awareness of the ill-effects of microbes, as well as how to prevent them, can lead to the minimization of diseases. For example, the USDA states that any frozen food purchased should be inspected carefully for broken seals or refrozen products. A mishandled food product with these conditions increases the potential for microbial contamination.

Another way in which foodborne botulism can be prevented is through the implementation of statewide standardization measures of proper food canning methods. For example, over 200 licensed canning companies in California must abide by strict rules outlined by the Cannery Inspection Program, concerning standards of hygiene and canning methods. If the facility fails to meet minimum standards, the state of California will force a recall of that product and prevent further manufacturing until standards are met.

If a health care provider is aware of an individual that has been negatively affected by a microbe from a food source, the health care provider should notify the state public health authorities, which then, in turn, notify the CDC, USDA and the FDA. Diagnostic tests are then performed to explicitly identify the microbe responsible.

Although the United States attempts to minimize the amount of cases of Clostridium botulinum per year, it cannot be completely eradicated. Advancements in food technology was not enough to prevent an outbreak of the botulinum toxin in chili sauce in 2007. Although all of the products were recalled after eight incidents, there was still another individual whom became ill after consuming the contaminated food product.

A Guide to Home-Canning

These jars of jalapeño peppers contaminated with botulinum toxins are an example of improper sealing of foods (cite#).

In an effort to prevent the prevalence of foodborne botulism from increasing in the United States, the USDA implemented a guide to home-canning. This guide suggests methods of “selecting, preparing and canning” fruits, vegetables, meats, jams and jellies.

In general, home-canned foods should be performed with the following conditions:

Be sure that the jars used are washed in hot water and 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 spores live or not. At high acidic levels, or at low pH levels, the botulinum toxin would not be able to grow.
- Low-acid level (pH>4.6) allows for botulinum toxin growth
- High-acid level (pH<4.6) prevents botulinum growth
The product should be sterilized at temperatures of 240-250 degrees Fahrenheit in order to ensure that the microorganism is destroyed.

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

Center for Disease Control and Prevention. Department of Health and Human Services. Disease Listing: Botulism General Information. Web. <http://www.cdc.gov/nczved/dfbmd/disease_listing/botulism_gi.html>.

United States Department of Agriculture. Food Safety and Inspection Service. Frozen, Fully-Cooked Products & Botulism - Food Safety Advisory. Sept. 2001. Web. <http://www.fsis.usda.gov/Fact_Sheets/Frozen_Fully_Cooked_Products_&_Botulism/>.

California Department of Health Care Services. Food and Drug Branch. Cannery Inspection Program. Web. <http://www.dhs.ca.gov/fdb/HTML/Food/indexcan.htm>.

Centers for Disease Control and Prevention. Department of Health and Human Services. Botulism Associated with Canned Chili Sauce, July-August 2007. Center for Disease Control and Prevention, 21 Aug. 2007. Web. <http://www.cdc.gov/botulism/botulism.htm>.

United States Department of Agriculture. USDA Complete Guide to Home Canning. 1994. USDA Complete Guide to Home Canning, 2006 revision. Web. <http://www.uga.edu/nchfp/publications/publications_usda.html>.

Edited by Carolina Ceballos, Cristina Flores, Nancy Gomez, Malisa Tov, students of Rachel Larsen