a. Bacteria (singular is bacterium) are single-celled plants. They are all quite
small but can vary somewhat in size. The typical bacterium is about 1/25,000 of an
inch; it would take as many as 25,000 individual bacteria placed side by side to equal
b. Some bacteria are able to produce spores. A spore is a stage in the life cycle
of a bacterium whereby the bacterium has a thick, hard cell wall. The tough cell wall
protects the spore from heat, cold, or other destructive agents. Spore-forming bacteria
are much more difficult to destroy than regular bacteria. The resistance of spores to
destruction is important in food sanitation. Cooking and refrigeration alone will not kill
all spores; other precautions must be taken.
c. There are many bacteria able to produce disease in man. This subcourse will
discuss the control of those bacteria causing foodborne disease. Bacteria are the most
common cause of foodborne disease.
Viruses are microorganisms that are even smaller than bacteria. In fact, they
are the smallest and simplest form of life. They can be seen only through a powerful
microscope called the electron microscope. Viruses are not able to reproduce on their
own; they must enter the cells of a living organism and cause these cells to assist in
producing more viruses. Viruses come in a variety of shapes and vary in their
Parasites are organisms that live on or in another organism (the host).
Parasites vary in size. Some are one-celled like bacteria and can be seen only through
a microscope while others are multi-celled and can be seen without a microscope.
Parasites are a special problem for soldiers stationed overseas in countries which use
human fecal matter as a fertilizer.
REQUIREMENTS FOR BACTERIAL GROWTH
Since bacteria are the most common source of foodborne disease, many of the
regulations for food service facilities are designed to prevent or slow bacterial growth.
To better understand why a food service facility must follow these regulations, the
preventive medicine specialist should know the basics of bacterial growth.
a. Bacteria reproduce simply by dividing in two. Each of the two new cells then
divides, and so forth. This type of reproduction leads to an explosive increase in the
number of bacteria within a few hours. For example, in just one hour, a single bacteria