Klebsiella pneumoniae survival and regrowth in endoscope channel biofilm exposed to glutaraldehyde and desiccation.

Biofilm in endoscopes is a major problem that can result in failure of disinfection. We studied the survival of K. pneumoniae in a biofilm formed on endoscope tubes subjected to combined chemical and physical stresses. We monitored bacterial survival in the biofilm after the action of 1% and 2% GTA either immediately or after 15 days of desiccation and described the ability of surviving bacteria to recolonize endoscope tubing in a dynamic model. There were surviving bacteria after 5-min exposure to 2% and 1% GTA. The percentage of survivors after 2% and 1% GTA was greater when the GTA treatment was performed after 15 days of prior desiccation of the biofilm. The survivors were able to recolonize and reform biofilm on abiotic surfaces probably because of the survival of persisters in a viable but non-culturable state in the biofilm. Our findings emphasize that the current guidelines on endoscope reprocessing should be strictly followed but that once constituted the biofilm in endoscope tubing will be very difficult to eradicate with present practices.