Bacteria-Filtering Effect of a Filtering System Used in Eye Drops

ABSTRACT

PURPOSE: A filtering system (ABAK system, Thea(R), France) was developed and has been used to prevent the abuse of preservatives and to decrease the complications that may result from them. However, the bacteria filtering effect of the system has not been reported yet. In this study, we attempt to verify its efficacy. METHODS: Staphylococcus epidermidis was diluted to two different concentrations, 10(7) and 10(5) CFU (Colony-Forming-Unit)/ml. To determine the inward-filtering effect of the system (reverse direction), 0.5 ml of each bacterial concentration was aspirated through the ABAK system, and the solutions that filtered through were cultivated. The results were compared with the controls in which the same amounts of bacterial solutions were dropped from a dropper by squeezing the bottle. For the outward-effect (forward direction), 1ml of bacterial solution from each concentration was put into the bottle with a syringe. Solutions were re-collected by filtering them out through the ABAK system by squeezing the bottle and also by aspirating them from the bottle with a syringe. Both solutions were cultivated, and the results were compared. Each test was repeated 5 times. RESULTS: In control solutions that did not pass through the filter, bacteria were cultivated consistently in repeated tests. However, bacteria were not cultivated in solutions that had passed the filter in both concentrations and in both directions. CONCLUSIONS: Filtering systems prevent solutions from contamination, and even if the bottles are polluted with Staphylococcus epidermidis initially, the bacteria would be filtered out. The effectiveness of the filtering systems was also demonstrated in high bacterial concentrations.