Food Borne Disease caused by Bacteria | Intestinal tracts of animals

Bacteria That Cause Food-borne Disease

Food-borne disease often shows itself as flu-like symptoms such as nausea, vomiting, diarrhoea, or fever, so many people may not recognize the disease is caused by bacteria or
other pathogens on food. They can grow in just about any food, but are fond of protein foods, such as meat, poultry, seafood, eggs, and dairy products in particular, as well as
high-protein vegetables such as beans and grains.

Bacteria multiply rapidly between 40° and 140° F. To keep food out of this “danger zone,” keep cold food cold and hot food hot. Store food in the refrigerator (40° F or below) or freezer (0° F or below); cook food to 160° F; maintain hot cooked food at 140° F; reheat cooked food to 165° F.


It is a rare but serious paralytic illness caused by a nerve toxin, botulin, that is produced by the bacterium Clostridium botulinum. Botulinic toxin is one of the most powerful known to man, with a lethal dose of a microgram. It acts blocking nerve function and leading to respiratory and musculoskeletal paralysis.

Clostridium Botulinum Food borne disease
Clostridium Botulinum

Some other bacteria cause more serious illness than others, but only a few are responsible for the majority of cases.

Below is the information regarding nine prominent bacteria.

Campylobacter jejuni:

Found in intestinal tracts of animals and birds, raw milk, untreated water, and sewage sludge. Transmission through contaminated water, raw milk, and raw or under-cooked meat, poultry, or shellfish.

Campylobacter jejuni Food Borne disease Bacteria
Campylobacter jejuni

Clostridium botulinum:

It is widely distributed in nature: in soil and water, on plants, and in intestinal tracts of animals and fish. Bacteria produce a toxin that causes illness. Improperly canned foods, garlic in oil, and vacuum-packaged and tightly wrapped food can invite it.

Clostridium botulinum Food Borne Disease Bacteria
Clostridium botulinum

Clostridium perfringens:

Found in soil, dust, sewage, and intestinal tracts of animals and humans. It is called “the cafeteria germ” because many outbreaks result from food left for long periods in steam tables or at room temperature. Bacteria is destroyed by cooking, but some toxin-producing spores may survive.

Clostridium perfringens Food Borne Disease Bacteria
Clostridium perfringens

Escherichia coli O157:

Found in intestinal tracts of some mammals, raw milk, unchlorinated water; one of several strains of E. coli that can cause human illness. It is transmitted through contaminated water, raw milk, raw or rare ground beef, unpasteurized apple juice or cider, uncooked fruits and vegetables; person-to-person.

Escherichia coli O157 Food Borne Disease Bacteria
Escherichia coli O157


Found in intestinal tract and feces of animals; Salmonella enteritidis in raw eggs. It transmits through raw or undercooked eggs, poultry, and meat; raw milk and dairy products; seafood.

Salmonella Bacterial food borne disease

Streptococcus A:

Found in noses, throats, pus, sputum, blood, and stools of humans. Transmission- people-to-food from poor hygiene, ill food handlers, or improper food handling; outbreaks from raw milk, ice cream, eggs, lobster, salads, custard, and pudding allowed to stand at room temperature for several hours between preparation and eating.

Streptococcus A Bacterial Food Borne Disease
Streptococcus A

Listeria monocytogenes:

Found in intestinal tracts of humans and animals, milk, soil, leaf vegetables, and processed foods; can grow slowly at refrigerator temperatures. Transmission- soft cheese, raw milk, improperly processed ice cream, raw leafy vegetables, meat, and poultry. Illness caused by bacteria that do not produce toxin.

Listeria monocytogenes Bacterial Food Borne Disease
Listeria monocytogenes

Shigella :

Found in human intestinal tract; rarely found in other animals. Transmission- person-to-person by fecal-oral route; fecal contamination of food and water. Most outbreaks result from food, especially salads, prepared and handled by workers using poor personal hygiene.

Staphylococcus aureus :

Found in on humans (skin, infected cuts, pimples, noses, and throats). Transmission – people-to-food through improper handling. Multiply rapidly at room temperature to produce a toxin that causes illness.

Staphylococcus aureus Bacterial food borne disease
Staphylococcus aureus

Biotechnology and Bacteria

Biochemistry is defined as the application of organisms such as bacteria, fungi and algae to the manufacturing and services industries. These include:

  • Fermentation processes, such as brewing, baking, cheese and butter manufacturing, chemical manufacturing such as ethanol, acetone, organic acid, enzymes, perfumes, etc.
  • Pharmaceuticals, such as antibiotics, vaccines and steroids.
  • Energy, in the form of biogas.
  • Food products, such as beverages, dairy products, amino acids and proteins.
  • Agriculture, such as animal feed, composting processes, pesticides, nitrogen fixation, plant cell and tissue culture.
  • Microbial mining, which is the bacteria and other microorganisms are cultured in container and then used to bring these processes e.g., copper extraction.

Genetic engineering and bacteria:

Genetic engineering is the manipulation of genes. It is also called recombinant DNA technology. In genetic engineering, pieces of DNA (genes) are introduced into a host by means of a carrier (vector) system. The foreign DNA becomes a permanent feature of the host, being replicated and passed on to daughter cells along with the rest of its DNA.

Bacterial cells are transformed and used in production of commercially important products. The examples are production of human insulin (used against diabetes), human growth hormone (somatotrophin used to treat pituitary dwarfism), and infections which can be used to help fight viral diseases.

Fibre retting:

Bacterial populations, especially that of Clostridium butyclicum, are used to separate fibres of jute, hemp, flax, etc, the plants are immersed in water and when they swell, inoculated with bacteria which hydrolyze pectic substance of the cell walls and separate the fibres.These separated fibres are used t make ropes and sacks.


Some bacteria living in the gut of cattles, horses and other herbivores secrete enzyme cellulose that helps in digestion cellulose contents of cell wall. Cellulose in the major source of energy in these animals.

Vitamins synthesis:

Escherichia coli living in human colon synthesize vitamin B and release it for human use. Similarly, Clostridium butyclicum is used for commercial preparation of riboflavin, a vitamin B.

Waste disposal:

Aerobic and anaerobic bacteria are used to decompose sewage wastes. They break down organic matter to harmless, soluble sludge in settling tanks. The methane gas produced is used as energy source. Similarly toxic chemicals synthesized by living organisms and those present in the pesticides are disposed with the help of bacteria. Pseudomonas putida has been created by using genetic engineering techniques and can break down, xylene, and camphor.

Agents of disease:

Organisms which cause disease are called pathogens. Some bacteria are pathogens Some bacteria are pathogenic and cause diseases both in animals and plants. However, pathogenic bacteria more commonly affect animals than plants.

Food spoilage:

Saprotrophic bacteria attack and decompose organic matter. This characteristic has posed problem to mankind as food such as stored grains, meant, fish, vegetable and fruits are attacked by saprotrophic bacteria and spoiled. Similarly milk and products are easily contaminated by bacteria and spoiled.

Vaccine Manufacturing Bacteria:

Bacteria are used in a very large scale to produce antibiotic drugs. A bacterial vaccine
is a preparation of dead or weakened bacteria. Vaccine of diptheria, pnenumonia, cough, cholera, tetanus, etc. is prepared using bacteria.

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