The prevention of the formation and elimination of biofilm in endoscope channels is a current topic in the reprocessing of flexible endoscopes. It is being discussed whether, with regard to its elimination, biofilm can be regarded as...
...an accumulation of microorganisms which can be inactivated by disinfection or sterilization, or
...a "fouling" consisting of extracellular polymeric substances (EPS) with trapped microorganisms, which can be removed by cleaning,
be regarded as a "contaminant".
According to current knowledge, classical biofilms consist of about 20% microorganisms and about 80% EPS.
International standards for testing disinfectants and disinfection processes do not include efficacy tests against microorganisms in biofilm. Papers have appeared in the scientific literature describing limited efficacy of some antimicrobial agents against microorganisms embedded in biofilms. In other publications, efficacy has been demonstrated only at application concentrations up to 20 times higher, depending on the type and age of the biofilm.
With regard to the efficacy against biofilm of low-temperature sterilization processes, which can be used in endoscope reprocessing, I'm personally not aware of any publications as author.
For cleaning agents, there is also no international standard for testing the performance for removing biofilm. However, publications describe the efficacy of cleaners, canal brushing, and mechanical cleaning procedures with increased mechanical assistance.
In the majority of publications, biofilm produced on microtiter plates is used to demonstrate efficacy. Another test method, using a biofilm grown in a tube, is described in the international series of standards EN ISO 15883 "Washer-disinfectors". This test is mandatory for testing the cleaning performance of washer-disinfectors for thermostable endoscopes as part of the manufacturer's type testing.
Conclusion:
The first priority is to prevent the formation of biofilms.
Elimination of biofilms from endoscope channels once they have formed can be most reliably ensured by thorough cleaning with mechanical assistance using tested agents and equipment. The preferred procedure is manual cleaning including brushing of the channels followed by further cleaning and disinfection in a washer-disinfectors for thermostable endoscopes tested according to the EN ISO 15883 series.
About the author
PD Dr. Holger Biering studied chemistry at Martin Luther University Halle-Wittenberg, where he also completed his doctorate and habilitation. Until 2010, he worked in various management positions in research and development at Ecolab. Since then he has been working as a consultant for cleaning and disinfection of medical devices for companies and users in the healthcare sector. Holger was an advisory member of AKI until 2022.