Introduction to Bacteriology

Bacteriology is the study of bacteria. Bacteria are microscopic organisms composed of a single cell. In bacteriology, the structure, functions, and growth of various bacteria have been discovered. Bacteriology has also explored the positive and negative impact of bacteria in the environment and in human beings. Another important function is the identification of bacteria that often cause disease in man and animals, and the mechanisms of how they bring about infection. This is an important aspect of bacteriology, which leads to the development of antibiotics or antibacterial drugs known to treat diseases caused by bacteria. Bacteria are single-celled microorganisms that lack a nuclear membrane, are metabolically active and divide by binary fission. Medically they are a major cause of disease. Superficially, bacteria appear to be relatively simple forms of life; in fact, they are sophisticated and highly adaptable. Many bacteria multiply at rapid rates, and different species can utilize an enormous variety of hydrocarbon substrates, including phenol, rubber, and petroleum. These organisms exist widely in both parasitic and free-living forms. Because they are ubiquitous and have a remarkable capacity to adapt to changing environments by selection of spontaneous mutants, the importance of bacteria in every field of medicine cannot be overstated. The discipline of bacteriology evolved from the need of physicians to test and apply the germ theory of disease and from economic concerns relating to the spoilage of foods and wine. The initial advances in pathogenic bacteriology were derived from the identification and characterization of bacteria associated with specific diseases. During this period, great emphasis was placed on applying Koch’s postulates to test proposed cause-and-effect relationships between bacteria and specific diseases. Today, most bacterial diseases of humans and their etiologic agents have been identified, although important variants continue to evolve and sometimes emerge, e.g., Legionnaire’s Disease, tuberculosis and toxic shock syndrome.