How to Control Fungus in Cleanrooms

Fungal issues are significant in controlled environments. To ensure your cleaning agent will be effective against mold and yeast, follow this series.

Fungal contamination from mold and yeast are concerns for cleanrooms in any industry. Mold issues in particular have surfaced in cold rooms, door kick plates, incubators, and cleanroom startups in addition to the cleanrooms themselves.

One of the major concerns, outside of properly testing for and catching contamination, is finding an effective disinfectant. Not all disinfectants are effective against fungal spores; you might have to use a sporicidal agent to control fungi. Another issue is that fungus will develop a resistance to products, so you need to rotate at least two different ones that are equally effective.

When selecting a disinfectant, you need to take critical steps to ensure you choose an effective agent. Here is the first:

Gather all information and data.

Before you can test products or even choose them, you need all the information necessary to make your decision. Collect all the relevant and available information from the suppliers. The information you want includes:

  • • Technical data sheets
  • • MSDS
  • • Recommended directions for use
  • • Review all available testing on substrate compatibility, stability, and microbial efficacy
  • • Ensure these tests were performed in accordance with accepted standards (AOAC, ASTM, EN)
  • • Check that the product was manufactured according to local, state, and country regulations
  • • Certificate of manufacture/analysis
  • • Audit supplier’s change control policies to ensure you’re notified of any significant changes to the product
  • • Any other information you need to compare products and make the appropriate selection

Selecting a Disinfectant for your Cleanroom

There are numerous types of fungi that can grow in your cleanroom. Selecting the right disinfectant(s) depends on several processes. In part one, we discussed the different types of relevant data you want to collect. Here we will discuss testing disinfectants for efficacy.

Many factors influence the effectiveness of the active ingredients in biocides. Some of them include:

  • • Concentration
  • • Surface type
  • • Contact time
  • • pH
  • • Organic soil
  • • Bioburden
  • • Hardness of the water
  • • Temperature

The actives used against fungal spores will perform differently depending on the factors above. It is therefore necessary to perform in-house testing. For pharmaceutical environments in particular, a series of tests are necessary. Some agents that work against vegetative fungi aren’t effective against fungal spores. Here are three methods to consider.

  1. Suspension Tests:
    These tests work to determine the time necessary to reduce an acceptable amount of organisms. However, they do not address efficacy within various surface types. The microorganism is suspended in the appropriate dilution of the test disinfectant. This should be done at room temperature at selected time intervals. After neutralizing any remaining disinfectant from the sample, viable counts can be performed.
  2. Carrier Tests:
    Here is where you will test efficacy on hard surfaces. You use a carrier made of the type of surface(s) in your cleanroom (e.g. stainless steel) to test disinfection agents. Typical cleanroom surfaces include stainless steel, terrazzo flooring, epoxy, vinyl, lexan, and glass.
  3. Statistical Comparisons:
    This is an ongoing test comparing the frequency of isolation and the number of organisms isolated before and after disinfection. It’s important to carry these tests out throughout the year. You may find seasonal variations that alert you to facility or maintenance issues.

In the end, the disinfectant application process should be validated. If you have questions about these processes, contact Gerbig Cleanrooms at 888-628-0056 or