Can disinfecting pharmaceutical facilities create microbiological risks?

The question may seem surprising, but the problem is very real.

To illustrate it, we spoke with Denis Streitt, Senior Global Technical Consultant at Ecolab.

He shared one of his real-life experiences… and trust us, it’s absolutely fascinating!

The Mystery of the “White Residue”

A pharmaceutical lab contacted Denis to report an unusual issue:

Their new chlorine-based sporicidal disinfectant was leaving white residue on the wipes after cleaning.

Denis checked all usage parameters over the phone (contact time, concentration, etc.), but no solution was found. So, he decided to pay them a visit.

During observation in production, the white residue was clearly visible.

Looking closer, it seemed to come from the coating of the sandwich panels in the cleanroom. Ouch!

Could the disinfectant be damaging the paint?!

An Unexpected Chemical Reaction

Chlorine (present in the disinfectant) is known to be a strong oxidizing agent. That’s exactly why it’s used as a sporicide. But the downside is that it can also be corrosive to surfaces if not rinsed properly after use.

However, since the disinfectant was recently introduced, it seemed unlikely it had already damaged the surfaces.

So, the investigation continued.

Then, an operator mentioned that ever since they started using the new disinfectant, they’ve been experiencing throat and respiratory irritation.

Hmm… interesting observation! But once again, it couldn’t come solely from the alkaline chlorine-based disinfectant.

There had to be something else… but what?

Denis then asked to see the cleaning and disinfection procedures, especially the rinsing steps (rinsing is so important!).

He noticed that no specific rinsing frequency was defined—suggesting a likely rinsing issue (or even no rinsing at all).

A possible lead!

He then asked which other disinfectants were used in rotation with the chlorine-based sporicide.

The answer? Another sporicide (!) based on peracetic acid…

And that’s when all the puzzle pieces fell into place.

The residues from the alkaline chlorine disinfectant, not properly rinsed, reacted with the peracetic acid, releasing… dichlore.

And there you have it— dichlor is toxic and irritates the respiratory tract.

BINGO, the culprit was found!

Root Cause Analysis

As is often (well, pretty much always!) the case in the pharmaceutical industry—when there’s a risk, it calls for a… risk and root cause analysis!

That’s exactly what was done in this case study to assess the potential impacts of insufficient rinsing and the interaction between the two disinfectant molecules.

Here’s what the analysis revealed (in short!):

1. Risk for operators: Inhalation of toxic gases.
   
2. Microbiological risk of false negatives: Residual disinfectant can interfere with surface microbiological testing.The neutralizers in contact plates might not be effective enough to counter high levels of disinfectant residues.
   
   This could lead to underestimating contamination—posing a serious risk of false negatives.

3. Risk of reduced disinfection efficiency: One might think that using two disinfectants at the same time doubles the effectiveness… but actually, it’s the opposite!
   
   The molecules from the two disinfectants can interact and reduce the overall effectiveness of the disinfection, increasing the risk of… contamination.

Corrective Actions

A risk analysis is great—but now it’s time to implement corrective actions so the lab can safely resume operations.

1. Keep only one sporicide for routine use
   
   The lab simplified its disinfection protocol by keeping the easiest-to-use sporicide for routine operations. The second sporicide would be reserved for curative actions in case of contamination.
   
   This action aligns with Annex 1, chapter 4.33: “Disinfection should include the periodic use of a sporicidal agent.”
   
   
2. Establish a rinsing protocol
   
   A clear rinsing frequency was defined to avoid any buildup of residues.
   
   This step, in line with Annex 1, chapters 4.33 & 5.4, eliminates the risk of interactions between the two disinfectant molecules.

Conclusion

Since these adjustments, there are no more white residues, no more irritations, and the microbiology lab results are spotless (well, as spotless as they can be)!

A big thank you to Denis Streitt for sharing this story, which reminds us all to think carefully about disinfectant use and the importance of rinsing protocols.

Even though it all starts with chemistry, it always ends up impacting our microbiological results!

On your side, have you ever experienced something like this in your lab?

Feel free to share it in the comments… we’d be happy to turn it into an article!