Module 8 - Foodborne Disease

Botulism

Another type of food poisoning is Botulism. The bacteria that causes this dreaded exotoxin is Clostridium botulinum.

What is foodborne disease?

Any illness resulting from ingesting of contaminated food.

Food handlers in Clostriadium perfringens

Food handlers play a minimal role as a source of this bacteria. Meat and poultry products are the most common sources of C. perfringens in foodborne illness. Cured meats are seldom implicated, due to the enhanced lethality from the curing agents in combination with other processes.

Type A

Toxin is poisonous to humans, and this is the most common cause of botulism in the United States.

The first salmonella

1885 by Dr D.E.Salmon , chief of the Bureau of Animal Industry of the US department of Agriculture; and medical reports of that day indicate this was a common disease problem

Prevention of Staphylococcus Aureus

Controlling temperature is the most effective route to control S. aureus food intoxication. Adequate heat processing and proper cooling and refrigeration are important control measures

Two kinds of food infections

In one, the food does not ordinarily support the growth of the pathogenic microorganism but merely carries them. Pathogens such as those which cause hepatitis A, tuberculosis, diphtheria, brucellosis, cholera, and others can be transmitted in this manner. In the second, the food not only act as a carrier but also can serve as growth medium for the pathogen. The greater number of cells resulting from this growth will increase the likelihood that an infection will occur when the food is consumed.

Type E

Toxin is poisonous to humans and is usually associated with fish, fish products and the aquatic environment.

Bacillus cereus two distinct type of illness

emetic and diarrheal, are produced by B. cereus, due to the production of two types of toxins. The emetic (vomiting) response is the most severe and acute, occurring within a few hours after ingestion. This response is likely due to ingestion of the preformed toxin. The diarrheal response results from the production of a toxin in the intestine. The symptoms are mild and take longer to develop occurring about 8-20 hours after ingestion.

Food Infection

an illness caused by ingestion of food containing viable microorganisms which they grow and establish themselves, usually in the gastrointestinal tract of the host, resulting in tissue damage and illness. The infection may be directly due to colonization of the intestine or due to metabolites produced as the bacteria grow in the intestine. The type of food infection resulting from metabolites (toxins) produced in the intestine is called toxicoinfection.

Foods for human consumption most commonly contaminated with salmonellae include:

1. poultry, meat, and meat products such as meat pies, pressed beef, sausages, cold cooked meats, reheated meats and gravies. Raw foods of animal origin are the major sources of salmonellae in kitchens of restaurants, institutions, and homes. 2. Eggs (including duck or turkey eggs) and egg product such as dried egg powder, egg albumen, frozen egg, and synthetic cream often prepared from frozen egg. 3. Raw milk and raw milk products such as ice cream, cream, custard, cream-filled confectioneries, and salad creams. 4.Fish, prepared fish dishes and shellfish, especially oysters obtained from uncontrolled beds which may be polluted.

Shigella dysenteriae symptoms

A highly infectious organisms. Illness may occur after ingestion of as few as 10 cells. with some species of Shigella, 10-100 organisms can cause illness in adults. After an incubation period of 1 to 7 days, the symptoms of shigellosis are manifested by diarrhea, abdominal pain, fever, and vomiting. In severe cases, there may be bloody diarrhea, mucus secretia and dehydration. Symptoms can persis for 3 to 14 days. In most cases, shigellosis is self-limiting but antibiotics may be required in the young or in severe cases

Clostridium botulinum

Botulism is a true food intoxication caused by eating food that contains an enterotoxin produced by Clostridium botulinum. Before an illness can result, the microorganism must grow in the food and produce the toxin before it is consumed. The organism that produces this potent toxin is a gram positive, rod‑shaped, anaerobic, spore-forming bacteria. The toxin which it produces is the most powerful poison known to man. It has been estimated that one cupful (eight ounces) of purified botulism toxin is enough to kill every human in the world! The mortality rate is close to 60 percent. At present there are six different types of botulinum toxin. These are distinguished by serological classification.

Prevention of Bacillus cereus

Control measures to prevent outbreaks of illness are directed at avoiding temperature abuse of previously cooked products. Cooked foods should be held at temperatures greater than 60°C until served or rapidly cooled to below 10°C for storage. To facilitate rapid cooling to the center of food products, the maximum thickness of food products should be such that an internal temperature of 15°C is reached within 2-3 hours after cooking. Foods which have been cooked and chilled should be fully reheated before serving

Control of Foodborne Disease

Elimination of outbreaks of foodborne disease requires constant attention to correct food handling practices and an awareness of the problem and methods of prevention. This includes: Good sanitation practices, safe temperature storage.

Define food infection. How do the two types of food infections differ?

Food infection is illness caused by the ingestion of a food containing viable organisms that are capable of causing illness. The two types of food infections differ because some organisms are not capable of multiplying in the food (e.g., Hepatitis A, tuberculosis) while others are capable of multiplication (e.g., Salmonella, Listeria, etc.).

What conditions are necessary for an outbreak of staphylococcus food poisoning?

In order for the illness to occur, four conditions are necessary: 1. The food must contain enterotoxin producing staphylococci. 2. The food must be suitable for growth of the organism and subsequent toxin production. 3. The temperature of the food must be suitable for growth of the organism, and there must be sufficient time to produce enterotoxin. 4. The enterotoxin contaminated food must be eaten.

The four types of food most commonly contaminated with salmonellae are:

Salmonella is most often associated with poultry and poultry products, eggs, raw milk and raw milk products, and fish especially shellfish from contaminated waters.

Camplobacter enteriditis Symptoms

Symptoms of campylobacter enteritidis, usually following a 2 to 3 day incubation period, include profuse diarrhea (sometimes bloody), abdominal cramps and nausea. In most cases, campylobacter enteritis is mild with patient recovery in less than one week. The pathogenicity of this organism is not well understood, but the organism is thought to be invasive and release an endotoxin (toxin is released when the cells die) within the gastrointestinal tract.

Types of Clostridium botulinum

The six types are: A, B, C, D, E and F.

Type F

Toxin is poisonous to humans, and this is extremely rare and was only recently isolated.

Type B

Toxin is poisonous to humans, and this is found more often than Type A in most countries of the world.

Type C

Toxin is poisonous to waterfowl, turkeys, cattle, mink and other animals but not yet demonstrated to be toxic to humans.

Type D

Toxin is responsible for forage poisoning of cattle, but this is rarely poisonous to humans.

Vibrio parahaemolyticus

Vibrio parahaemolyticus and other Vibrios associated with foodborne illness are normally inhabitants of marine environments. Outbreaks are frequently associated with consumption of oysters and other shellfish from warm coast waters. Vibrios are sensitive to drying but are able to grow in salt concentrations of up to 10%. Growth is very rapid at 30-37°C, but slow at temperatures below 10°C. Control of this foodborne organism to prevent illness involves preventing the multiplication of the organism in raw products by refrigeration and hygienic measures designed to prevent recontamination of cooked foods.

The following conditions are necessary for an outbreak of C. perfringens gastrointestinal infection:

1.The food contains or becomes contaminated with C. perfringens. 2.Usually the food is cooked, resulting in a greater anaerobic condition in the food; also competing organisms in the food are destroyed. 3.The food is inadequately cooled and favorable temperatures and enough time are allowed for appreciable growth from the surviving spores. 4. The food is consumed without reheating so that large numbers of viable cells are ingested. 5. The cells sporulate in the intestine and elaborate the enterotoxin. In general, any food prepared and kept warm for long time periods before consumption may be a cause of this type of food poisoning. Thus, persons attending large banquets where foods are prepared ahead of time and kept warm for several hours become prime targets for this type of foodborne illness.

Food poisoning

An illness that is caused by consuming food containing a performed poison (toxin). Toxin is produced by the bacteria growing in the food. Food poisoning can also occur by ingestion of mycotoxins, toxins of poisonous mushrooms, plants or shellfish, and poisons associated with pesticides, herbicides, or other chemical contaminates.

Outbreak

An occurrence of an illness involving a number of individual cases or persons who have become ill. Thus, when talking about foodborne illness, the number of cases always will be greater than the number of reported outbreaks Outbreaks may involve a great may persons, but the mortality rate is low (less than 1%). Deaths that do occur are normally in infants, older people and those suffering from other diseases.

Clostridium botulinum Outbreak

An outbreak is usually associated with canned foods. Home-canned foods are the greatest cause of botulism in the United States. In the period 1960-1969 there were 79 outbreaks of botulism, and 41 of these were caused by home-canned foods. Why are canned foods usually the cause of botulism? These bacteria are found in the soil; therefore, they are commonly found on foods such as green beans, peas, spinach and some fruits. Since they are spore-forming organisms, they have the ability to survive heat treatments that kill most other bacteria. They also can grow under anaerobic conditions, which is usually the case in canned foods. Thus, if canned foods receive a sub-lethal or less than sterilization heat treatment, conditions in that canned food are favorable for growth of Clostridium botulinum. The growth will then result in toxin production. C. botulinum cannot grow and produce toxin in any foods with a pH of 4.5 or less. Home-canned fruits are not associated with C. botulinum poisonings.

Bacillus cereus

Bacillus cereus is a common spore forming bacteria in soils and on vegetation. It is frequently isolated on a variety of foods, including dairy products, meats, spices and dried products and cereals, especially rice. The spores of B. cereus will survive cooking. The potential for foodborne illness occurs when the surviving spores germinate in the cooked food product. If the food product is held at temperatures allowing the growth of the bacteria, the organism grows to large numbers releasing a toxin in the food as well as in the intestine when ingested. Ingestion of about 108 cells/gram is usually required to produce illness. Bacillus cereus food poisoning can be classified as either a food intoxication or a food infection as the toxin may be preformed in the food or produced in the intestine. This bacterium has an optimal temperature for growth of 30°C, with a minimum of 10°C and a maximum of 49°C. The pH range for growth is from 4.9 to 9.3

Examples of Food Intoxications / Food Poisoning

Bacterial Food Intoxications: 1. Staphylococcus aureus 2. Clostridium botulinum Fungal Food Intoxications: 1. Mycotoxin (molds), including poisonous mushrooms Chemical Food Poisonings 1. Heavy Metals (Arsenic, lead, mercury) 2. Pesticides, Herbicides, and insecticides Others: 1. Poisonous plants 2. Toxic Shellfish

Example of food infections

Bacterial food infections: 1. Salmonella spp 2. Shigella Dysenteriae 3. Clostridium perfringens 4. Campylobacter jejuni 5. Yersinia Enterocolitica 6. Listeria monocytogenes 7. Vibrio spp 8. Escherichia coli O157:H7 9. Bacillus cereus Viral Food Infections: 1. Infectious hepatitis (Hepatitis A) 2. Norwalk virus

Why are outbreaks of botulism usually associated with home-canned foods? What are the six types of botulism toxin? How does the botulism toxin differ from that produced by S. aureus?

Botulism outbreaks are most commonly associated with low acid, home canned foods because the heat treatment needed to destroy the spores is not possible in homes. The six types of botulism toxins include toxins A, B, C, D, E, and F. The Staphylococcus aureus toxin differs from Clostridium botulinum toxin in that the Staphylococcus toxin is heat stable and affects the gastrointestinal tract while the Clostridium toxin is destroyed by heat and affects the nervous system.

C.jejuni prevention

C. jejuni infections can be prevented by properly pasteurizing or cooking foods and avoiding cross-contamination of cooked foods with foods or equipment on which raw foods have been handled.

Source of Campylobacter jejuni

C. jejuni is widely prevalent in the feces of a variety of wild and domestic animals, in particular birds. For this reason, the organism is principally associated with raw foods of animal origin. Raw milk and poultry are commonly implicated as vehicles of foodborne outbreaks. This bacteria has long been identified as a pathogen of domestic livestock, where it is associated with spontaneous abortion and other pathology. Foods may be contaminated with C. jejuni due to contact from the intestinal contents of animals during processes such as slaughter, milking, and inadequate washing of hen's eggs. Infected food handlers can also contaminate foods when hygienic practices are poor. Fecal contaminated water sources may be another source.

Clostriadium perfringens

Clostridium perfringens is the anaerobic bacteria responsible for gas gangrene of deep tissue wounds. When present in foods, this organism can cause gastrointestinal illness. Food poisoning usually occurs 8-24 hours after ingestion of food containing one million or more Clostridium perfringens vegetative cells. The illness is caused by sporulation of the bacterial cells in the intestine, accompanied by production of an intracellular enterotoxin. Sporulation and release of toxin can also occur in the food, but generally the toxin produced in the intestine appears to be responsible for the illness. The toxin damages intestinal cells, resulting in excessive fluid accumulation in the intestine C. perfringens has exacting nutritional needs, requiring 13 to 14 amino acids and five to six growth factors. These nutritional requirements may play a role in the types of foods associated with this foodborne illness. Foods usually incriminated in outbreaks caused by this organism are often high in protein, such as meat, meat gravies and meat dishes. C. perfringens is anaerobic, and grows best when air or oxygen is not present. Heating of food, particularly liquids such as gravies or soups, drives out air and oxygen and creates an ideal environment for the growth of these organisms, unless proper precautions are taken after heating to prevent growth. Other growth requirements of C perfringens include a maximum temperature for growth of about 55°C with an optimal of 43 to 47°C. It will not grow well in acidic foods as 5.0 is the lower limit of pH tolerance, nor is it tolerant of greater than 5% salt.. The ability to form spores is an important factor in its role as a foodborne pathogen. Spores on raw meat and poultry can survive cooking and grow when the cooling food product reaches a suitable temperature. Rapid, uniform cooling is therefore essential. Foods should be cooled to below 10°C within 2-3 hours. Previously cooked food held for serving the next day, should be reheated to a temperature of 75°C immediately before serving to destroy vegetative cells. As a general rule, fully cooked meats should be kept above 60°C or below 4°C.

Commercial processes

Commercial processes used to can foods are designed to provide sufficient heat treatment to destroy spores of C. botulinum. In most instances, processes are developed which are far in excess of this minimum requirement. Spore-forming bacteria that are much more heat-resistant than C. botulinum spores are used to establish these processes. For example, a company wishes to process and sell a canned beef product — what heat process should be used? To develop this requirement, data from inoculated pack runs have been established. This is done by inoculating a batch of the beef product with spores of a highly heat resistant organism. A commonly-used strain are the spores of PA3679. This organism is a Clostridia, and it has been established many times that it is much more heat resistant than C. botulinum. The inoculated pack is given a heat treatment and then incubated to determine if this organism has survived and can grow. This technique is continued until a process is found that provides maximum destruction of PA3679. This process then will provide assurance that C. botulinum will not survive, grow and cause botulism. The toxin of botulism is different than that produced by S. aureus in that it can be destroyed by heat. Boiling for a few minutes is sufficient heat to inactivate the toxin. The spores of the organism are heat resistant, but the toxin produced by the organism is not. However, while boiling inactivates the toxin, the clostridia spores are still living and able to produce more toxin if given a chance.

Escherichia coli

Enteropathogenic E. coli is a significant cause of diarrhea in developing countries. It is associated with "travelers" diarrhea. There are several types of enteropathogenic E. coli based upon the type of pathogenicity produced (i.e., toxin production, invasiveness). The hemorrhagic strain, O157:H7 is responsible for the outbreaks of which have occurred in North America, now commonly referred to as "hamburger disease." It is also known as hemorrhagic colitis or bloody diarrhea. Severe abdominal cramps also characterize the disease. Incubation time is 3-4 days, with a duration of 2-9 days. In healthy adults the symptoms may be very mild and go virtually unnoticed. Particularly in children, however, the illness may progress to a potentially fatal kidney dysfunction, known as Hemolytic Uremic Syndrome. It is not known what number of organisms must be ingested to cause infection. The more frequent occurrence of symptoms in children suggests a lower resistance to the bacteria such that a small number of organisms are sufficient to cause illness. Non-pathogenic E. coli bacteria are normal inhabitants of the intestinal tract of animals and humans, occurring at levels of millions per gram of feces. Humans are thought to be the principal if not the only reservoir of toxigenic and invasive strains of E. coli. In contrast, animals are thought to be the principal reservoirs of the hemorrhagic O157:H7. This strain has been isolated from many food products including beef, fruits, vegetables and processed products such as cheese and mayonnaise. In recent outbreaks of hemorrhagic E. coli, contamination of beef with feces has been presumed to be the source although this is not conclusive. Human-to-human transmission through poor hygiene is a known route of transmission. As in many foodborne outbreaks, one needs to consider if it is the food that presents a risk to the people or the people that present a risk to the food. The optimal temperature for growth of E. coli is 37°C, with a range of growth of 10 to 40°C. The optimal pH is 7.0 to 7.5, with a minimum of 4.0 and the maximum is 8.5.

Define food intoxication. List two types of microbial food intoxication.

Food intoxication is the ingestion of a food containing a toxin that can cause illness. Several examples are the toxins produced by Clostridium botulinum, Staphylococcus aureus, and molds.

Foods most commonly involved in outbreaks of Clostridium perfringens food poisoning are ________________ and ________________ which have been cooked and held for some time. What growth characteristic of this bacteria allows it to grow in heated liquids such as gravies or soups?

Food most commonly involved in Clostridium perfringens food poisoning is meat gravies and meat dishes which have been cooked and held for some time. Clostridium perfringens is an anaerobe that is capable of growth at 55°C. Cooking destroys the vegetative cells, but does not necessarily destroy spores. Salmonella and Staphylococcus aureus are both destroyed by cooking, but in the case of Staphylococcus the toxin is heat stable and this can still cause illness after cooking.

Limit or prevent contamination of the food by the microorganism.

Foods become contaminated with bacteria in many ways. It is impossible to produce food (grow, process and prepare) in a nice, little, sterile bag that keeps out bacteria. Consequently, most foods are contaminated from the time they leave the farm until they are used. Others become contaminated during subsequent handling and processing after they leave the producing farm. Meat and poultry may be contaminated during slaughtering and processing operations by organisms carried in waste material of animal origin. These raw products may carry the organisms into food preparation areas and contaminate equipment and personnel handling the food. From these sources other foods may become contaminated. Any food may be contaminated with disease-causing microbes from dirty equipment, dust, insects, rodents and fecal-borne organisms of animal or human origin. Obviously, the observance of proper personal hygiene and processing techniques will reduce contamination, but it does not always prevent it. There are procedures that can be used to effectively limit the amount of contamination of foodstuffs. The one most frequently used is separation of processes so that one stage of the process does not contaminate the next. Slaughter areas are separated from deboning lines to help prevent contamination of the deboned meat with microorganisms from the freshly-killed animals. It is obvious that the finished product should be handled in such a manner that it does not become contaminated. If the processing of the product destroys the foodborne disease organisms, then recontamination must be prevented. Prevention of contamination of food with microorganisms that cause foodborne illness is an effective way to help control the problem. This is particularly true with foodborne diseases such as Salmonellosis or Staphylococcus aureus food poisoning. However, it will not do the trick alone. This principle must be used in combination with the other two principles for complete control of outbreaks of foodborne disease.

Yersinia enetrocolitica

Gastroenteritis due to Y. enterocolitica is infrequent despite its isolation from the gastrointestinal tract of most animals. Many isolates of this organism are non-pathogenic. A pathogenic strain has been isolated from the intestinal tract of swine; however, no outbreaks have been directly associated with pork. Documented cases of Y. enterocolitica infection have occurred after ingestion of chocolate milk, pasteurized milk and tofu. In the outbreak involving tofu, contaminated spring water in which the product was packaged was determined to be the source of the organism. Y. enterocolitica is sensitive to heat (50°C), sodium chloride (5%) and acidity (pH 4.6). However, it is one of the few foodborne pathogens that can grow at refrigeration temperatures. Refrigerated at 7°C for 10 days, this organism is capable of growing from a few hundred cells to millions per gram. Refrigeration, an important means of controlling the growth of foodborne pathogens, is not an effective measure for controlling yersinia. It is important to eliminate the organism from foods by pasteurization or cooking and avoiding cross-contamination of raw products, particularly meats.

Good sanitation practices

Individuals handling food either at home or in a food-processing plant should observe good sanitation practices to minimize opportunities for contamination. All buildings, equipment and utensils used for processing food should be designed and constructed so thorough cleaning will be easy and practical. Processing plant personnel should be encouraged to practice sound personal hygiene and to report any illness, skin infection, rash or boils. Food handlers should be encouraged to wear plastic or rubber gloves that can be cleaned and sanitized frequently or discarded. Every effort should be made to prevent contamination of the food. Those handling prepared food should: 1.Always work with clean hands. Never use your hands to mix food when clean, sanitized utensils are available. 2 Always wash hands thoroughly after going to the toilet or handling raw food. A final treatment with a sanitizing solution on the hands can be useful. 3.Wear clean and sanitary plastic or rubber gloves whenever possible, particularly if there is a cut or skin irritation on the hands. 4.Keep hands away from skin infections, mouth, nose and hair 5Cover coughs and sneezes with tissue or check with supervisory personnel if condition warrants. 6.Don't use cooking utensils or fingers to taste food while cooking or serving; don't lick fingers or eat while preparing food. 7.Kitchen equipment should be well scrubbed to prevent cross- contamination between raw and cooked foods. 8.Avoid cross-contamination between raw and cooked foods.

Listeria monocytogenes

Listeriosis, the disease caused by Listeria monocytogenes was previously known as a disease associated with abortions and encephalitis in animals. Since the 1980s, L. monocytogenes is recognized as an important foodborne pathogen in humans. L. monocytogenes is widely distributed in nature and survives very well in soils and on vegetation. Reported outbreaks of listeriosis have been attributed to vegetables fertilized with manure from infected sheep. Meat products from infected animals can serve as a source of the organism in the food supply. Pregnant woman, the fetus, newborn infants and immuno-compromised individuals are most at risk for listeriosis. The disease may be manifested as septicemia, meningitis or meningoencephalitis. Approximately 30% of the immunocompromised, newborns and young children may die from listeriosis. When the disease invades the central nervous system such as in encephalitis, the death rate may be as high as 70%. In most healthy people, ingestion of the bacteria may result in a flu-like illness or go unnoticed. However, a carrier state may develop. As many as 5% of symptomless persons may be excreters of L. monocytogenes. The growth requirements of L. monocytogenes include a pH range of 5.0-9.5 in a good growth medium. This organism is very salt tolerant and relatively resistant to drying. L. monocytogenes is able to grow at refrigeration temperatures of 4°C and at this temperature its resistance to other factors such as drying increases. The ability of this bacteria to double its numbers every 1.5 days at 4°C increases the difficulty of controlling L. monocytogenes.

Salmonellae

Nearly 2,000 serotypes of the bacterial genus Salmonella have been isolated from humans and animals. Many of these bacteria are responsible for the disease salmonellosis, which is one of the major foodborne illnesses affecting man today. When ingested, salmonellae live and grow in the intestinal tract. This disease spreads easily, passing in a continuous infecting cycle from animal to man, man to man, man to animal, and environment to man or animal. Salmonellae can be picked up at any time during the various stages of production, processing, storage or preparation of foods for human or animal consumption. Foods and/or beverages so contaminated are primary agents of disease transmission, while infected persons/animals are secondary ones. Salmonellae usually do not affect the appearance, smell, or taste of the food within which they grow. The most vulnerable foods are those that are subjected to negligent handling or processing and those that are lightly cooked or used without any further cooking. Once any foodstuff is contaminated, conditions may develop enabling bacteria to grow, and under some conditions they grow and reach numbers sufficient to cause illness in a relatively short period of time

Prevent or inhibit the growth of the microorganism.

Of the principles of foodborne disease control, this one seems to be the most applicable for control of food poisoning outbreaks associated with prepared foods. The key to control is to prevent growth of these organisms in cooked and cooling meat, poultry, meat broths and other foods that might support their growth. Under circumstances commonly encountered in food preparation and service, the best way to prevent growth is to adjust the food temperature to such a degree that growth is inhibited. These organisms grow best over a range of temperatures from 37°C to 49°C. The farther the temperature deviates from the optimum, the slower the growth. The growth becomes slower and slower as the temperature increases or decreases until a temperature is reached where growth is stopped. The control mechanism is, therefore, temperature adjustment of the food. Prevention of outbreaks can be achieved by the effective use of refrigeration, storage and chilling of hot food at temperatures below 4°C or holding of hot food at temperatures 60°C or above.

Campylobacter jejuni

Only recently isolated as a human pathogen, Campylobacter jejuni is now recognized as one of the leading causes of acute bacterial gastroenteritis in humans. Evidence suggests that campylobacter is responsible for at least as many cases of foodborne illness as salmonellae. This bacterium was once classified as Vibrio fetus. C. jejuni does not grow well outside a living host. It requires a temperature of 30°C to grow but can survive well at refrigeration temperatures. It is sensitive to heat (inactivated at above 45-50°C), oxygen, acids and disinfectants. In spite of its fragility, the frequency of C. jejuni illness is high. This is because ingestion of low levels of viable cells (a few hundred cells) can cause illness, suggesting the organism is highly virulent.

Cause of Staphylococcus Aureus

Outbreaks of foodborne staphylococcus intoxication occur as a result of eating foods that contain a toxin produced by the bacterium, Staphylococcus aureus, during growth in the food. The toxin is very heat stable and is not destroyed by normal cooking or pasteurizing processes. This toxin is called an enterotoxin because it causes inflammation and irritation of the lining of the stomach and intestinal tract.

Salmonellae control measures

Requires a combination of approaches from the farm through to the kitchen. In the kitchen, the most common method of eliminating salmonella from food products is heat processing. These organisms are heat sensitive and ordinary pasteurizing or cooking conditions are generally sufficient to kill salmonellae in high moisture foods. As with other microorganisms, the heat resistance increases as the food moisture content (aw) decreases. In properly heat-processed foods, the occurrence of salmonellae indicates post-processing contamination from raw products, contaminated equipment or unhygienic handling. Acidification of food products and lowering of the water activity are also effective in preventing the growth of salmonellae. For example, during sausage fermentation the combination of acidity and sodium chloride is the principle method of control.Freezing and frozen storage has some lethal effects on all bacteria including salmonellae. Generally, however, bacteria remain viable for long periods of time under frozen storage. Frozen storage, therefore, is not effective in preventing the occurrence of bacteria in foods. As with freezing, Salmonella may survive for extended periods of time in dehydrated products.

What are the symptoms of these four illnesses? Are there any differences in the symptoms? What might they be?

Salmonella symptoms: diarrhea, nausea, abdominal pain, chills, fever, and vomiting within 1-7 days. Campylobacter symptoms: diarrhea (perhaps bloody), nausea, and abdominal cramps within 2-7 days. Staphylococcus symptoms: diarrhea, headache, shallow respiration, and low body temperature. Symptoms can appear within as little as two hours.

Salmonellae in animals

Salmonellae may also be found in many types of animal feeds. When an infected animal is slaughtered, it can contaminate the packing plant and employees who have contact with it or the slaughter area. Slaughterhouse scraps then are used as supplements in animal feed. If improperly processed or reinoculated, these scraps containing bacteria contaminate feed and subsequently other animals.

Shigella Dysenteriae

Shigellosis or bacillary dysentery is caused by bacteria of the genus shigella. The intestinal tract of humans and other primates are the normal habitat of shigella and only rarely is this bacteria isolated from other animals. The disease is mainly transmitted from person to person by the fecal-oral route. Food may become contaminated with the organisms from asymptomatic carriers or persons recovering from the disease. Similar to salmonella bacteria, shigella may persist in the intestinal tract for months following an infection. Shigellosis is an important problem in countries where unsanitary or crowded conditions exist, including institutions and daycares.

Staphylococcus aureus

Staphylococcus intoxication or food poisoning is one of the most common forms of foodborne diseases affecting man today. The actual number of outbreaks occurring each year is difficult to determine, because cases may occur that never get reported. An outbreak of foodborne staphylococcus intoxication may involve large groups of persons when it occurs at banquets, picnics or public institutions. When this happens, publicity results and action is taken to determine the cause of the illness. However, a great many outbreaks may involve only a few persons and may be confined to one or two individuals in a family. In such instances no attempt is made to determine the cause, and quite often the illness is disregarded as "stomach flu" or a "virus" and forgotten in a short time. Consequently, it is very difficult to document and diagnose the cause of the sickness. The primary sources from which food poisoning staphylococci enter foods are either human or animal. The nasal passages of humans are laden with these organisms. At least 50% of healthy people carry S. aureus as part of the normal microbial population of the nasal cavity. Boils, pimples, acne and infected skin wounds are also sources of these organisms. Poor personal hygiene of food handlers is an important source of contamination. Staphylococci are becoming increasingly important as a cause of mastitis in cows, and some of these cocci can produce enterotoxin, and thus may be a source of food poisoning in raw milk and milk products. S. aureus also commonly occurs on the skin and hides of animals and therefore may contaminate products as a result of dressing procedures. Usually when an outbreak of staphylococcus food poisoning occurs, not all individuals who have eaten the contaminated food become ill. Why is this the case? Individuals vary in their susceptibility to the action of the toxin. The amount required to make one individual sick may not affect a second person, whereas this same concentration of toxin may make another individual quite ill. In an outbreak, it is possible to have varying degrees of illness in different individuals all of whom have eaten the same amount of contaminated food. The incubation period for this type of food poisoning is usually from a minimum of two to four hours to a maximum of eight to 12 hours. This differs from other common types of foodborne infections, such as salmonellosis, which usually has a longer incubation period.

Safe temperature storage

Storing food at low temperatures by freezing or refrigeration is an effective prevention to microbial growth. However, this does not destroy the organism, and once the food is placed in a more favorable temperature, growth can occur. Prepared food that will not be consumed immediately should be refrigerated as quickly as possible, so the center of the food reaches 4°C within a short time. The use of shallow containers will help in lowering temperatures of the food quickly. Be sure that food to be served cold is kept cold, below 4°C, until consumed. Heat will destroy most microbes that cause foodborne illness. Adequate cooking will assure destruction of these organisms. But regardless to what temperature the food is heated, recontamination of the food after heat treatment often occurs and should be prevented. Heat treatment will not destroy any Staphylococci enterotoxin that may be present in the food before cooking. Since no detectable change in the food is produced by these bacteria when growing and producing toxin, it is essential that food be handled properly before cooking as well as after. A good motto to follow is: "When in doubt — throw it out." Storing prepared food at temperatures that enhance the growth of microorganisms should be avoided. When food is exposed to temperatures between 4°C and 60°C, holding time should be kept to a minimum. All foods should be refrigerated promptly after a meal or cooking and should be stored at a temperature below 4°C. The prevention of outbreaks of foodborne disease requires diligent attention to details of sanitation, food handling practices and temperature control. Only through the concentrated efforts of all individuals involved can an unpleasant experience at a social gathering or family dinner be prevented.

Vibrio parahaemolyticus symptoms

Symptoms of foodborne illness due to V. parahaemolyticus include acute gastroenteritis (vomiting, nausea, cramps, fever, chills, and diarrhea). The disease is usually mild but can be fatal. In Japan, due to the consumption of raw seafood, V. parahaemolyticus is responsible for 50‑70% of all foodborne gastroenteritis.

Yersinia enetrocolitica Symptoms

Symptoms of foodborne illness due to Y. enterocolitica are often quite severe, particularly in children. Symptoms are a sharp pain in the lower right abdomen, mimicking appendicitis; and diarrhea, fever, and vomiting. Complications such as septicemia and meningitis may occur.

In order for Staphylococcus aureus to occur, four conditions are necessary:

The food must contain enterotoxin producing staphylococci. The food must be suitable for growth of the organism and subsequent toxin production. The temperature of the food must be suitable for growth of the organism, and there must be sufficient time to produce enterotoxin. The enterotoxin contaminated food must be eaten.

Salmonellae food poisoning symptoms

The food poisoning usually appear between 6 to 48 hours after ingestion of contaminated food or beverage. Variation in incubation time may be attributed to the size of the infecting dose, the virulence (degree of pathogenicity) of the Salmonella species, the susceptibility of the person and the physicochemical composition of the transmitting food. Therefore, its difficult to establish what the number of cells ingested per meal is necessary to cause illness, but for the more virulent serotypes as few as 10^7 cells per meal can cause illness in susceptible individuals. Salmonellosis is characterized by an abrupt onset of diarrhea, nausea, abdominal pain, prostration, chills, fever, and vomiting. Symptoms generally last 1 to 7 days, intensity varies. Outbreaks may involve a great may persons, but the mortality rate is low (less than 1%). Deaths that do occur are normally in infants, older people and those suffering from other diseases. For omst, salmonellosis is a self-limiting gastroenteritis which may be misdiagnosed as intestinal influenza by the patient of physician. Therefore, the occurrence is greatly under reported.

Destroy the microorganism by some treatment of the food.

The heat treatment involved in the thorough cooking of most foods is usually sufficient to kill those organisms that cause Salmonellosis or S. aureus food poisoning. But these treatments will have little if any effect on spore forming organisms such as C. botulinum or C. perfringens or on heat stable toxins such as S. aureus. Consequently, cooking cannot be considered a reliable means of destroying the latter two pathogenic bacteria. To achieve the destruction of spores of these two organisms requires a much greater heat treatment. As a result, other means must be utilized to prevent outbreaks of foodborne illness caused by these two organisms. As was indicated earlier, the processes for canning food are dependent upon heat necessary to destroy spores of C. botulinum. Thus, this illness can be controlled effectively by following proper canning techniques. The other types of microorganisms that cause foodborne disease, such as Salmonella, C. perfringens and S. aureus are a little more difficult to control. These organisms are somewhat ubiquitous, and often contaminate food after it has been processed or cooked, and is awaiting consumption. Control at this point is dependent upon the third principle of prevention.

Staphylococcus aureus intoxication.

The most common type of food poisoning caused by bacteria is Staphylococcus aureus intoxication. Staphylococcus aureus can grow readily in many foods, and it produces an enterotoxin while growing. The term Enterotoxin can be applicable to any type of toxin which exerts its effect on the intestinal system.

Prevention of Listeria monocytogenes

The organism is inactivated by heat treatments, above that required for minimum pasteurization. Heat processes of milk may require 76.4-77.8°C for 15.4 seconds to inactivate this organism. Control measures involve strict sanitation regiments and prevention of cross‑contamination of raw product and finished product equipment and personnel.

Prevention of Escherichia coli

The organism is relatively heat sensitive and can easily be destroyed by pasteurization temperatures or by proper cooking processes. The recommended temperature to destroy E. coli O157:H7 in hamburger is 66.1°C for 41 seconds. Control measures include hygienic product preparation from slaughter through to the finished product, adequate refrigeration and adherence to recommended cooking processes.

Shigella dysenteriae principal foods

The principal foods associated with outbreaks are a variety of salads and seafood which become contaminated during handling by infected workers or a carrier whose personal hygiene is poor. Improper refrigeration of contaminated products increases the likelihood of an outbreak. Harvesting of seafood from fecal contaminated waters and use of non-potable water in food preparation may also be sources of the disease particularly in underdeveloped countries. S. dysenteriae is sensitive to heat processing and do not survive in acid pH of below 4.5.

Growth of Staphylococcus aureus

The range of conditions under which staphylococci will grow and hence produce enterotoxin in food varies. S. aureus is facultative in respect of its oxygen requirements; however, oxygen is required for toxin production. Some of the toxin-producing staphylococci are very salt-tolerant, growing in salt solutions of 10-20% NaCl. They also tolerate nitrites to such an extent that under favorable conditions growth can occur in curing solutions and on cured meats. Staphylococci will also grow in fairly high concentrations of dissolved sugars (50-60% sucrose). The temperature at which these organisms grow varies depending upon the type of contaminated food. But, in general, they will grow in a wide range of temperatures from about 4°C to approximately 46°C. At the lower temperatures, growth is slow; but at the higher temperatures growth is very rapid. The minimal pH for growth is about 4.8 and the maximum is 8.0. The minimum aw for growth is 0.86, the lowest of any of the food poisoning bacteria. It should be emphasized that when growing in food these organisms produce no obnoxious odors, nor is the appearance or flavor of the food altered in any way. Thus, it is almost impossible to sense the presence of staphylococci or enterotoxin by the appearance of the food. While normal cooking temperatures are sufficient to kill the bacterial cells, the enterotoxin is heat stable and not inactivated by heat. Therefore, the inability to detect viable S. aureus cells does not ensure that a food is safe. Ordinarily Staphylococcus aureus contaminates a food product in low numbers. The organism is usually outnumbered by other types of bacteria in a raw food product. Due to competition for the available nutrients in the food, S. aureus will not grow to appreciable numbers. However, when contaminated onto a cooked food product, the competing organisms have been eliminated by the heat treatment. When these conditions occur together with temperature abuse of the product S. aureus can grow to large numbers and form toxin. Any food requiring a great deal of hand labor in preparation, such as salads, casseroles and hors d'oeuvres are a possible source of staphylococcus food poisoning, particularly if the food has been mishandled after preparation.

Clostriadium perfringens symptoms

The symptoms are diarrhea and severe abdominal pain. Nausea is less common, fever and vomiting are unusual, and mortality is rare except for the debilitated or elderly.

Staphylococcus aureus symptoms

The symptoms include salivation as well as typical gastrointestinal symptoms, head and muscular aches, weak pulse, shallow respiration and subnormal body temperature. Symptoms persist until the toxin is removed from the system, but recovery in most cases is complete within 24 hours. For the most part, no treatment is given except in extreme cases when saline solutions may be given to restore the salt balance and counteract dehydration. Death from this illness is extremely rare.

In your own words, discuss, in one or two paragraphs, control of foodborne disease.

The three general principles related to the control of foodborne disease are to: Limit or prevent contamination of the food by the microorganism. Destroy the microorganism by some treatment of the food. Prevent or inhibit the growth of the microorganism.

The four most common types of foodborne illness in this country are:

The three most common foodborne illnesses in Canada are caused by Salmonella spp., Campylobacter jejuni, and Staphylococcus aureus.

Types of Clostriadium perfringens

There are several types of Clostridium perfringens. Some are part of the microflora of soils, others are found in the intestinal tracts of all animals including humans. The production of spores contributes to the ability of this organism to inhabit a wide range of environmental conditions.

Principles of Control

There are three general principles related to the control of foodborne disease: 1. Limit or prevent contamination of the food by the microorganism. 2.Destroy the microorganism by some treatment of the food. 3.Prevent or inhibit the growth of the microorganism.