This figure represents the various sources of exogenously acquired microorganisms and how failure to properly clean, disinfect and sterilize reusable medical equipment may lead to the introduction of microorganisms into the flexible endoscope. Possible sources of exogenously acquired microorganisms include: Residual microorganisms from previous patient use; Residual environmental microorganisms acquired during reprocessing; Wet storage following appropriate disinfection/sterilization.