Pharmaceutical Microbiology is an applied branch of Microbiology.
The Basics
It involves the study of microorganisms associated with the manufacture of pharmaceuticals e.g. minimizing the number of microorganisms in a process environment, excluding microorganisms and microbial by-products like exotoxin and endotoxin from water and other starting materials, and ensuring the finished pharmaceutical product is sterile.
Other Aspects
Other aspects of pharmaceutical microbiology include the research and development of anti-infective agents, the use of microorganisms to detect mutagenic and carcinogenic activity in prospective drugs, and the use of microorganisms in the manufacture of pharmaceutical products like insulin and human growth hormone.