By Bryan Brezoff, ID Section Leader, BS, SM(NRCM)
By Jacob Lee, Environmental Monitoring Study Director, BS
Frequently Nelson Labs receives questions from clients in regard to environmental monitoring (EM). It is a necessary tool to help us know when problems arise due to environmental contamination. EM testing, microbiological surveillance, or incubation and enumeration are important to ensure environments remain within a particular state of control throughout the product manufacturing process. Monitoring of the surface and air quality will provide a way to measure the quality control systems put in place to achieve a controlled environment (HEPA, air exchange, disinfectant program, etc.). The frequency of EM testing should be based upon the amount of control you are looking for and often relates to the type of controlled environment you are monitoring. Since EM testing provides a retrospective look at your environment it makes sense that if you require more control then you should test more frequently. A higher frequency of sampling allows you to take action sooner if you do happen to have an environment that is out of specification.
There are three basic test methods for EM testing:
- Passive Air—this involves testing the normal fallout of microorganisms from the air. It does not require any special equipment, only the passive fallout onto an agar plate for a specified period of time (usually 4 hours).
- Active Air—this involves using special equipment that will actively pull a specified volume of air through a vacuum and impinge the microorganisms onto an agar medium or filter.
- Surface Testing—surface sampling can be performed by contact plates or by swab sampling. At Nelson we always recommend contact (touch plates) sampling whenever possible because it provides a greater recovery of microorganisms than swab sampling can. However, if the surface you are trying to sample is irregular than contact plates would not be suitable and swab sampling would be necessary.
As part of the EM program, manufacturers must establish a baseline of data. This can involve up to a year’s worth of data collection. Through review of your baseline you will be able to establish alert and action levels and be able to identify areas with the highest environmental bioburden. The initial collection of data is very important. During this time it’s important to identify the organisms you recover from your EM testing. IDs should be set; especially the peaks, spikes and counts within the environment. It's part of the data collection process. Throughout the day the test is monitoring and establishing the microbial count, which may change over time. The initial testing should show you have it under control whereas on-going testing you will watch for spikes and irregularities that can cause significant problems and risks.
Locations for all EM tests are determined by the environmental sampling plan and based on operation—where work is going on, where critical steps in the process are conducted and where it makes the most sense by the manufacturer.
Again, manufacturers gain more control over their environments by routine monitoring of their environmental bioburden. Ideally, Nelson Labs recommends conducting clean room EM testing daily and controlled and other environments at least quarterly, but preferably monthly.
In an earlier blog, we talked about ID baselines. Nelson Labs encourages you to take your EM process another step to gram stain and ID the bacteria gathered by the monitoring. . Doing so will ensure you always have good data and during spikes and failures you will be able to save time and money by more quickly locating the source of problematic excursions. Remember, it is never too late to start your base line. It is a lot less costly and time consuming in the long run than the delays and costs associated with a contamination problem.