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Pathogens are microorganisms capable of causing disease. All these microorganisms are harmful to humans. They can survive in pure water as well as injected water. Pathogenic bacteria found in water systems are E.coli, Salmonella and Pseudomanas.
Typically, they are attached to water system filtration membranes such as reverse osmosis membranes and ultra-filtration membranes, or sometimes a biofilm can form in water system pipelines.
Sometimes pathogens are found in samples for microbial limit testing when we analyze purified water or water for injection (WFI). In that case, we should first reanalyze the sample to confirm the presence of pathogenic bacteria in the water system.
When such conditions occur, the entire water system should be cleaned. First the entire system should be sanitized with hot water (80⁰C) for 4-5 hours. All users and sampling points should also be flushed with continuous drainage of hot water for 15-20 minutes to properly remove pathogens.
Drain the water and flush the system at least twice with ¼ of the water storage tank. Fill the tank with fresh water. RO systems and ultra-filtration membranes should not be sanitized with hot water. This process only applies to the water recirculating loop connected to the water storage tank.
After sanitization, samples should be taken from each user point and analyzed for all pathogens according to standard operating procedures for clean water/WFI testing.
If pathogens are found again in the water sample, first disinfect with nitric acid solution (5%) followed by formaldehyde, chlorine or hydrogen peroxide (5%) to remove pathogens. They can be used with hot water for better results.
Ultraviolet light in the return loop plays an important role in keeping pathogenic bacteria out of the water system. The system should be properly cleaned and analyzed for traces of chemical use before the water is used in the manufacturing process.
Water systems should properly remove pathogens for at least seven days before reuse in pharmaceutical production.
