Archive February 2014 XV, No. 2

Beware the Biofilm

The microscopic residue of surgery and exams can cause big-time problems.

Michelle Alfa, PhD, FCCM


manual cleaning BRUSHING UP Diligent manual cleaning is essential to prevent biofilm from forming.

Biofilm is comprised of microorganisms, particularly bacteria and yeast that replicate in the presence of liquid. When biofilm forms on instruments and in flexible endoscope channels, a slimy layer helps protect the bacteria and yeast, making it difficult to eradicate once it forms. The problem is that scopes and instruments are becoming incredibly complex, making removing biofilm an increasingly difficult task.

Background on biofilm
Biofilm buildup can be especially common in flexible endoscopes. Even if reprocessing techs follow proper cleaning and disinfection protocols, subsequent storage with moisture in the channels can still lead to biofilm. Keeping internal channels clear of bacteria is important and requires attention to cleaning, disinfection and dry storage. Transmission rates of bacteria in flexible endoscopes are fairly high: Between 40% and 50% of patients treated with contaminated scopes will become colonized. The colonizing organisms may not cause infections immediately, but because the bacteria are antibiotic resistant, they'll be the "last bugs standing" in patients subsequently treated with antibiotics.

From a microbiology perspective, an absence of moisture means bacteria can't replicate and biofilm can't form. That's a pivotal point. Flexible endoscopes are supposed to be stored dry. If staff follow proper reprocessing practices and store scopes properly, biofilm won't be an issue.

However, the frontline perception of what's considered dry for endoscopes is not well understood and scopes stored with moisture in their channels are one of the biggest issues endoscopy centers face. After the final rinse, wipe down the exterior of the scopes, as well as the valves and attachments, with a lint-free cloth. Then purge all endoscope channels with 70% to 80% isopropyl alcohol followed by forced air to ensure channel drying. Finally, hang scopes in storage with the valves removed so the internal channels remain dry.

There is no standardized quality assurance program currently in place for endoscope reprocessing. According to the Association for the Advancement of Medical Instrumentation, the level of residual protein and hemoglobin in properly cleaned endoscopes should be <6.4 μg/cm2 and <2.2 μg/cm2, respectively.

Hopefully, updated national guidelines will soon require facilities to monitor the reprocessing of each endoscope to confirm proper manual cleaning has been completed before high-level disinfection, and to hold improperly cleaned scopes back from use until they're reprocessed correctly.

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