A study of the efficacy of bacterial biofilm cleanout for gastrointestinal endoscopes.

Aim: To compare the influence and clearance effect of enzymatic and non-enzymatic detergents against Escherichia coli (E. coli) biofilm on the inner surface of gastroscopes.

Methods: Teflon tubes were incubated in a mixture of different detergents and E. coli culture (10(6) CFU/mL) for 72 h at 15 degrees C, and biofilms on the inner surface of the teflon tubes were analyzed by bacterial count and scanning electron microscopy. To evaluate the clearance effect of detergents, after biofilms were formed on the inner surface of Teflon tubes by 72 h lavage with E. coli culture, tubes were lavaged by enzymatic and non-enzymatic detergents at a speed of 250 mL/min, then biofilms on the inner surface were analyzed by bacterial count and scanning electron microscopy.

Results: Non-enzymatic detergent had a better inhibition function on biofilm formation than enzymatic detergent as it reduced bacterial burden by 2.4 log compared with the control samples (P = 0.00). Inhibition function of enzymatic detergent was not significantly different to that of control samples and reduced bacterial burden by 0.2 log on average (P > 0.05). After lavaging at 250 mL/min for 3 min, no living bacteria were left in the tubes. Scanning electron microscopy observation showed biofilms became very loose by the high shear force effect.

Conclusion: Non-enzymatic detergent has a better inhibition effect on biofilm formation at room temperature. High speed pre-lavage and detergents are very important in temporal formed biofilm elimination.