The development of medical bacteriology since the
pioneering discoveries of the 19th century can broadly
be divided into pre-molecular and molecular phases.
An important account of the state of medical bacteriology
in the late pre-molecular age up to the 1930s is detailed
in A System of Bacteriology in Relation to Medicine [4]
and in William Bulloch’s The History of Bacteriology of
1938 [5]. It is important to recall that at that time virology
and immunology were still regarded as integral parts of
bacteriology; both of these then still embryonic sciences
were to give rise to the major independent sciences of
virology and immunology. The intensive study of the bacteriophages,
mainly those of Escherichia coli, which
began in the 1940s, would ultimately lead to the important
concepts and tools of molecular biology.