Introduction
Clostridium perfringens is a bacterium with a characteristic thick cell wall that, like that of all other gram-positive bacteria, is made of peptidoglycan. This property classifies it in the gram-positive group of bacteria. This chemical causes the purple stain when a gram stain procedure is performed on them. They have a wide range of habitats including animals’ intestines where it exists as normal flora as well as in soil. They may also be found in sewage. However, they are more likely to be found in foodstuff especially improperly cooked meat products. Unlike many living things, this bacterium grows and lives in the absence of free oxygen and is therefore referred to as anaerobic. The bacterium also grows best at a pH close to neutral ranging between 6.5 and 7.5 values (Novak, 2003, p. 387). This bacterium reproduces through the production of spores which are more persistent in soil and human feces.
Clostridium perfringens grow very well under a wide range of temperatures from 450 C to high temperatures of 1200C. This is the ideal temperature at which a single bacterium is capable of producing millions of progeny in a short period. When foods are improperly cooked, a strain of Clostridium perfringens develops and makes the food toxic which may even become fatal to humans and other animals including birds. For the spores to produce toxins in food, they require moisture, and therefore the food has to be moist (Schreck, 2010, p. 1). This bacterium mostly affects meat and poultry products.
Catalase and oxidase tests
Clostridium perfringens gives a negative result on catalase test. Since it grows in absence of oxygen, it obtains energy required for growth by breaking down proteins and from the fermentation of carbohydrates. Aerobic respiration which takes place in bacteria that grow in presence of free air produces a by-product, hydrogen peroxide, which is removed by catalase. The oxygen that is available in organic matter is all consumed by other types of bacteria leaving an anaerobic environment that is conducive for the development of clostridia spores. There is, therefore, no need for removal of hydrogen peroxide by-product by catalase hence this bacterium is catalase-negative. It is also oxidase negative and forms gas and acid from carbohydrates. These bacteria are indole negative as well (Todar, 2009, p. 1).
Food poisoning
Clostridium perfringens bacteria have been a major cause of a food-borne infection commonly known as food poisoning which results from poorly cooked meat especially poultry products. The toxin produced by Clostridium perfringens is heat resistant and can only be killed at temperatures of 750C and above. It is detected in foodstuff that is contaminated and poorly prepared as well as in feces. This is because clostridium spores can survive cooking temperatures and can multiply soon after cooling. After ingestion, it only takes these bacteria ten hours to produce spores and toxins which results in infection as they produce spores. However, many cases of Clostridium perfringens tend to be subclinical as antibodies against the toxin are always produced in the body of all animals. The toxins produced by these bacteria damage the tissues and cells of the intestinal tract resulting in conditions such as anaerobic cellulitis, myonecrosis, and gas gangrene (Todar, 2009, p. 1).
The most common of the implications of Clostridium perfringens is the gas gangrene which is the death of affected tissues starting with a wound in an anaerobic region especially in the limbs. The affected area is left with contamination of the spores of the clostridium. With low levels of oxygen, clostridium spores can multiply by germinating and thereby causing more cellular damage. Bacterial enzymes are produced which in turn produces a lot of gas which promotes further infection in muscles. When the gas is produced in large volumes, its pressure surpasses that of the arteries and causes the reduction of blood supply to cells causing the death of the whole affected tissue. Continued absorption of toxins may cause shock to tissues which are more likely to result in death (Novak, 2003, p. 387). However, a high dose of infectious toxins is required to cause death with the carrier state persisting for several days.
Symptoms of the diseases
A person infected with the common Clostridium perfringens experiences severe pain in the abdomen accompanied by nausea and occasionally vomiting. In rare cases, fever is also experienced. This occurs as the bacterium multiplies in the intestines which may start after ten hours of ingestion. Consumption of food that is contaminated with a type C strain of the clostridia causes enteritis necroticans which is a very severe illness. The severity of the symptoms may differ in different individuals with some experiencing less severe symptoms than others even after a long period after ingestion. In case a person suffers substantial problems with his/her health like dehydration, he/she may end up dying. Diagnosis of perfringens poisoning is done by observing specific symptoms of this illness and may be confirmed in a laboratory by culturing specimens on blood agar plates where the bacterium grows in absence of air producing colonies that cause complete hemolysis of red blood cells causing the media to appear light yellow and is usually transparent. The colonies are inoculated on another agar plate containing egg yolk to identify the toxin-producing colonies (Novak, 2003, p. 387).
Case report
Most outbreaks of food poisoning especially those that occur due to consumption of corned beef have been associated with the Clostridium perfringens bacterium as the major cause. This has been demonstrated in a case study from St. Patrick’s restaurant in the United States wherein one day; on March 18, 1993, cases of fifteen people who got sick after consumption of corned beef from the food shop were reported. Following the publication of this report, more than a hundred people reported abdominal disturbances 48 hours after they had eaten food from the same food shop. All cases showed symptoms of food poisoning such as vomiting, abdominal pains, and nausea. A large percentage of 92% of the cases reported constituted those who had eaten corned beef with the minority having eaten potato salad or roasted beef. However, no one was hospitalized (Kendall, 1997, p. p. 1047).
An inspection and follow-up were done at the St. Patrick’s café a day after the reports had been made. It was found that 1400 pounds of corned beef had been purchased due to the expected high demand for the product. Portions of the beef had been boiled after purchase for a few hours and left to cool at room temperature after which they were refrigerated. About four days after, they were removed from the refrigerator thus exposing them to warmer temperatures before they were served. Samples from the food shop were collected from leftovers of corned beef and were cultured in a bacteriology laboratory. More than a hundred colonies of Clostridium perfringens bacteria were isolated in every single gram of the samples.
On another occasion at the same venue, a traditional dinner was held after which 76% of those who had attended the dinner complained of having stomach pains, vomiting and diarrhea a few hours after eating a meal consisting of corned beef and vegetables. The outbreak was associated with the corned beef because all the infected people with an exception of one ate the beef. Cultures showed 106 colonies of Clostridium perfringens bacteria in every gram of the samples.
Probable causes of the outbreak
The major cause of all kinds of bacterial food poisoning is temperature changes. Clostridium perfringens is no exception because the bacterium multiplies in foodstuffs that are kept at room temperature for hours. The bacterium gets into the food during the cooking process either from the handler or from the materials being used. Once introduced into the food, clostridia develop vegetative spores that are heat stable and are therefore able to resist the normal cooking temperatures. When the food is left to cool or taken out of the refrigerator, the spores multiply in the food within a few hours. Clostridia do not, however, produce toxins in the food before consumption but rather in the stomach once ingestion has occurred (Doyle, 2009, p. 24).
The same applies to the case study above where bacteria were introduced into the corned beef during handling and were able to develop spores and multiply when the beef had been left to cool after heating as well as the time when it had been removed from the refrigerator before being served. After consumption of the corned beef, the spores developed into toxins which caused the symptoms reported. Besides temperature changes, lack of adequate hygiene causes the invasion of bacteria into foodstuffs from where the bacteria obtain nutrients for their growth.
Measures to prevent clostridia outbreak
Foods especially meat products should be cooked sufficiently to ensure that all bacterial spores are destroyed. It is advisable to heat food beyond the normal cooking temperatures because the spores are not killed at this temperature and may later germinate and multiply when the food cools. All leftover meat products should be refrigerated properly and reheated before being re-eaten. Foods that are more susceptible to containing clostridia should be avoided such as certain species of fish and other meat products. Food should be served hot immediately after cooking to prevent them from attaining room temperature. Keeping food in smaller amounts in the refrigerator can also help increase the cooling rate of the food. Monitoring of food shops should be practiced to ensure adequate cooking, storage temperatures as well as hygiene. Above all, proper hygiene is the key to avoiding recontamination of previously cooked food.
Conclusion
Most food poisoning outbreaks are associated with inadequate hygiene. It is therefore advisable for people to maintain cleanliness at home as well as animal keepers to prevent clostridia and other bacteria food poisoning. Proper cooking of food should be observed to kill the vegetative spores and prevent germination and multiplication of the bacteria. Infected people, as well as animals, should take large amounts of fluids to prevent dehydration resulting from diarrhea which is a very common occurrence in food poisoning patients.
Bibliography
Doyle, M. (2009). Foodborne Bacterial Pathogens. Marcel Dekker; New York.
Kendall, M. (1997). Hospital Outbreak of Clostridium Perfringens Food-poisoning. The Lancet, Volume, Issue 8020, pp. 1046 – 1048.
Novak, J. (2003) Viability of Clostridium perfringens, Escherichia coli, and Listeria monocytogenes surviving mild heat or aqueous ozone treatment on beef followed by heat, alkali, or salt stress. Journal of Food Protection; 66: 382-389.
Schreck, S. (2010). Outbreak Linked to Louisiana Hospital. Web.
Todar, K. (2009). Pathogenic Clostridia: Clostridium perfringens and Clostridium difficile. Web.