Joan O’Malley Manager Charles River Laboratories

Five Tips to Ensure Your Lab Disinfectants Are Working


Cleanrooms and other classified areas in healthcare and pharmaceutical facilities must be kept in a state of microbial control in order to maintain aseptic conditions and ultimately protect the product or patient. The current GMP lays the foundation for ensuring adequate conditions in a general sense.

Cleanliness of a manufacturing operation includes control of air quality as well as surface cleaning and disinfection in manufacturing areas. These conditions, combined with careful and thorough evaluation of the chemical agents used for the cleaning and disinfection program, should help achieve the specified cleanliness standards and control of microbial contamination of products.

The effectiveness of disinfectants and procedures should be measured by their ability to ensure that potential contaminants are adequately removed from surfaces. To ensure disinfectants are working, environmental monitoring (EM) must be performed at defined intervals.  This should include active and passive sampling and personnel monitoring. Monitoring must initially be performed in the cleanroom/facility in the “at rest” state, so as to prove that a certain level or classification of cleanliness can be achieved in an area.

Once this is achieved, EM must be performed “in operation,” to prove that the cleaning regimen and disinfectants are working. Bioburden testing on products during the various stages of production will also show that cleaning regimen and disinfectants are working. Here are five suggestions to ensure that your disinfectants are working in the lab.

  1. Test the efficacy of the in-use disinfectant. Make sure you perform the suspension test on the disinfectant in order to assess the contact time. You must also perform the surface disinfectant test on each type of material used in cleanrooms in order to assess the efficacy of the disinfectant with the surface type. A wide range of different materials are used in the construction of clean rooms and other controlled areas, so each material needs to be evaluated separately to validate the efficacy of a given disinfectant. Ensure that testing has been performed on the disinfectant to confirm its effectiveness, up to and including its expiration date, and that you test against in-house isolates (i.e., those recovered during environmental monitoring/bioburden testing). Lastly, perform bioburden testing on the in-use disinfectant to confirm its sterility.
  2. Select the right media. It’s important to confirm that the media used for the EM is effective in the recovery of organisms. Ensure that the EM media in use contains suitable neutralizers to inactivate any residual disinfectant that may be present in the environment that could be masking the growth of organisms present. You also must ensure that the media is capable of recovering bacteria and fungi. Viable monitoring is intended to detect organisms in the aerobic state; however, you may need to check for anaerobes if nitrogen is used in the manufacturing process.
  3. Probe the classified areas, too. It’s important that you perform EM (including personnel monitoring) in the classified areas in both at rest and in operational states, in order to detect the levels of bacteria and fungi present during a defined stage of the process. The results should be within the defined specification. If the EM data suggests a drift in commonly recovered environmental flora, a review of the disinfectant is required. The microbial isolates recovered should be trended on a periodic basis to identify isolates associated with environmental/personnel and product bioburden, atypical isolates, and the most frequently isolated organisms.
  4. Make sure bioburden tests remain within specification. If levels of organism recovered are low, it means that the disinfectant process steps are adequate for the removal of organisms. If test results tend to exceed the specification allowed, one cause could be that the disinfectant in use is not suitable for removal of organisms. Identify the contaminating organisms and test the efficacy of the disinfectant with these organisms.
  5. No cross-fertilization, please! Make sure there isn’t any cross-contamination between laboratories. If disinfection procedure is performed correctly, there should be no evidence of cross-contamination. If this happens, it can greatly impact your results by obtaining out-of-specification EM and bioburden results, ultimately leading to rework of the product and shutting down of the production process while investigations are performed to find the root cause and to determine the corrective and preventative actions.









































Joan O’Malley ([email protected]) is the manager of the microbiology department at Charles River Laboratories’ site in Ireland. Joan regularly blogs for Charles River’s science blog, Eureka, and recently wrote about microbial disinfectants.

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