SORPTION OF BACTERIAL-ENDOTOXIN AND RETENTION OF BACTERIA BY POSITIVELY CHARGED MEMBRANE FILTERS

Positively charged membrane filters (Pall, Posidyne(R)) were studied f or their ability to retain both bacterial endotoxins and bacteria. Fil ters (0.2 mum pore size) were challenged with high (up to 510(5) EU) levels of bacterial endotoxin. When the endotoxin was dispersed in wat er, a more than 10.000 fold reduction of the endotoxin was obtained, w hereas the reduction was only a factor 20 when Ringer's solution was u sed to disperse the endotoxin. Retention of bacteria was dependent on the type of organism, the pore size of the filter and the suspending l iquid. Although filters with pore sizes > 0.2 mum were not suitable to be used as a final filter in an aseptic production process, a very re duction in the number of bacteria could be obtained. Possible applicat ions for these filters in the production of sterile pharmaceuticals ar e discussed.