Water is a very serious source of microbiological contamination. Microorganisms, particularly Gram-negative bacteria, can grow and multiply in water, even when nutrients are only present in very low concentrations. Some such microorganisms evolve to form films or slimes, which adsorb nutrients from flowing water. Periodically these films are naturally sloughed off into the water stream.
Most microorganisms are unable to move or expand more than a few millimetres on dry, solid surfaces. Conversely, waterborne types are guaranteed to be found in practically every wet location, and in locations that have recently been wetted. Water is therefore a vector, as well as a source, of microbiological contamination.
The most likely types of microorganisms traceable to water are Enterobacteriaceae, including Escherichia coli and Salmonella spp. as the most readily recognizable types in domestically contaminated waters, and Pseudomonas spp., which are always found in natural, potable and pharmaceutical waters.
There are regulatory restrictions on the presence of water in clean rooms used for aseptically filling sterile pharmaceutical products. The restrictions are — on the face of it — quite simple: there should be no water outlets in these areas.
However, water is the most commonly used cleaning fluid and diluent for pharmaceutical products, cleaning agents, disinfectants. It is virtually impossible to have a completely water-free pharmaceutical clean room, and it is certainly impractical. Water-based fluids must be sterilized before entry to aseptic filling rooms, usually by filtration.
Water is permitted, and is indeed necessary, in the lower grades of clean rooms (change rooms, preparation areas, compounding areas, etc.), which surround and exist to service sterile pharmaceutical manufacture. Wherever possible it should be of pharmaceutical grade (of purified water or water for injection quality), microbiologically controlled and monitored. Personnel movement from areas in which there is water into high-grade, aseptic clean rooms may be an additional vector for waterborne contaminants.
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