Worst-case soiling levels for patient-used flexible endoscopes before and after cleaning

Background: The soiling levels of patient-used narrow-lumened flexible endo scopes were assessed for bronchoscopes, duodenoscopes, and colonoscopes. Th e effect of cleaning on the soil composition and concentration was evaluate d. Design: Suction channels from 10 each of bronchoscopes, duodenoscopes used for endoscopic retrograde cholangiopancreatography, and colonoscopes were a ssessed immediately after patient use for the levels of bilirubin, hemoglob in, protein, sodium ion, carbohydrate, endotoxin, and viable bacteria. Anot her 10 suction channels of each type of endoscope were evaluated for the sa me components after routine cleaning hut before processing by high-level di sinfection or sterilization for subsequent clinical use. Results: Recognizing that only soluble components could be quantified, the worst-cast soil levels in the suction channels (the average surface area of these channels was 45.6 cm(2), 149.8 cm(2), and 192.0 cm(2) for bronchosco pes, duodenoscopes, and colonoscopes, respectively) were protein 115 mu g/c m(2), sodium ion 7.4 mu mol/cm(2), hemoglobin 85 mu g/cm(2), bilirubin 299 nmol/cm(2), carbohydrate 29.1 mu g/cm(2), endotoxin 9852 endotoxin units/cm (2), and bacteria 7.1 (log(10)) colony-forming units (CFU)/cm(2). Colonosco pes had 4 to 5 times greater soiling on average compared with the other end oscope types. Routine cleaning reduced the levels of bilirubin to below the limits of detection for all endoscopes evaluated (limits of detection were <1 nmol/mL). After cleaning, residual hemoglobin was detectable in broncho scopes only After cleaning, the levels of protein, endotoxin, and sodium io n all were reduced fivefold to tenfold for all types of endoscopes. Carbohy drate was reduced to lower than the limit of detection for all endoscopes a fter cleaning, except the duodenoscopes. The average load of viable bacteri a was reduced from 3 log(10) to 5 log(10) CFU/cm(2) (which represents 5.9-9 .5 log(10) CFU/endoscope channel) after patient use to approximately 2 log( 10) CFU/cm(2) (which represents 3.2-5.3 log(10) CFU/endoscope channel) afte r cleaning. Conclusions: These data demonstrated that cleaning effectively reduced or e liminated many components of soil, but a substantial amount of viable bacte ria and protein remained. Hemoglobin levels in before samples indicated tha t blood was not present in high concentrations in the suction channels of t he majority of flexible endoscope samples. Soil that mimics the worst-case composition from patient-used endoscopes would be ideal for simulated-use s tudies for such medical devices.