Introduction

U.S. Department of Agriculture

Illustration of a bacterium. (Source: NIH)

The U.S. Department of Agriculture's Food Safety and Inspection Service characterizes Bacteria as living single-cell organisms. Bacteria can be carried by water, wind, insects, plants, animals, and people and survive well on skin and clothes and in human hair. They also thrive in scabs, scars, the mouth, nose, throat, intestines, and room-temperature foods.

Often bacteria are maligned as the causes of human and animal disease, but there are certain types which are beneficial for all types of living matter.

National Institute of Allergy and Infectious Diseases

Scanning electron micrograph of a number of Gram-negative Escherichia coli bacteria of the strain O157:H7. (Source: CDC)

The National Institutes of Health's National Institute of Allergy and Infectious Diseases characterizes Bacteria as living things that have only one cell. Under a microscope, they look like balls, rods or spirals. They are so small that a line of 1,000 could fit across a pencil eraser. Most bacteria won't hurt you – less than 1 percent makes people sick. Many are helpful. Some bacteria help to digest food, destroy disease-causing cells and give the body needed vitamins. Bacteria are also used in making healthy foods like yogurt and cheese. But infectious bacteria can make you ill. They reproduce quickly in your body. Many give off chemicals called toxins, which can damage tissue and make you sick. Examples of bacteria that cause infections include Streptococcus, Staphylococcus, and E. coli.

Antibiotics are the usual treatment. When you take antibiotics, follow the directions carefully. Each time you take antibiotics, you increase the chances that bacteria in your body will learn to resist them. Later, you could get or spread an infection that those antibiotics cannot cure.

Further Reading

• Germs: Understand and protect against bacteria, viruses and infection
• Microbes in Sickness and in Health
• Virus or Bacterium?