Microbiological Monitoring of the Environment

by Hale Ichinose
Microbiology Supervisor of Environmental Monitoring

A strong environmental monitoring program is an integral aspect of process validation.

It is also critical to protect product integrity from contamination, and contract manufacturers and developers should be able to demonstrate an organized, effective approach to the need.

Environmental monitoring in- volves evaluation of the controlled environment where the sterile materials are assembled and processed into the finished dosage form. A contract manufacturer's written monitoring program should include routine sampling and testing of the environment including room air, walls, floors, critical equipment surfaces and personnel monitoring. A review and reporting process should call attention to any results that exceed alert/action limits. Generally, because contamination could be caused either by the settling of microorganisms suspended in the air, or by manipulative procedures where component handling leads to contamination, environmental monitoring should be performed under static conditions as well as during the dynamics of filling.

There are some specific points to look for in a contractor's environmental monitoring program.

Often, filling rooms are protected entirely by HEPA-filtered, vertical laminar flow air and are classified as "Class 100" rooms. The immediate supporting areas are classified as follows: aseptic corridor(s) and the white gowning room are "Class 10,000"; and the supply system is designed so that air movement is from the critical areas to the clean areas and on to less clean areas. Con- tractors should be monitoring this air movement by pressure differentials between rooms. This is accomplished by a computerized system that continuously reads a pressure transducer to ensure clean areas are at a higher pressure than less clean areas.

An aggressive environmental program may employ four different methods of sampling; three methods to detect viable contamination and the fourth method to quantify non-viable or particulate contamination. These methods may include: swab testing — surface monitoring; rodac plates — surface sampling; sterilizable microbiological atrium (sma) — viable air sampling; and, particle monitors — non-viable particulates.

The program should allow for testing each aseptic controlled area at least twice each workweek and on every production day.

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