2011 Buyers' Guide 2011 Buyers' Guide - International Fiber Journal

case processing conditions. The effluentis collected and assayed quantitativelyby membrane filtration. Integritytesting is performed before and afterthe bacterial challenge procedure. Theselection of Brevundimonas diminutaas the challenge organism is based onliterature reports that the organism attainsa very small size when grownunder stress or minimal nutritionalconditions. The test procedure compliesin intent and content with theASTM F838-83 Standard Test Method“Determining Bacterial Retention ofMembrane Filters Utilized For LiquidFiltration” and the Health IndustryManufacturers Association (HIMA)Test Method “Microbiological Evaluationof Filters For Sterilizing Liquids”.Saline lactose broth is selected as thegrowth media because the literature reportsthat use of this media in concertwith carefully controlled growth conditions,results in a minimally aggregatedpopulation of Brevundimonas diminutacells, a significant percentage of whichwill pass through 0.45 µm membranes.The test objective of a most severe bacterialchallenge to the filter is met bythe challenge conditions, which includehigh pressure, high flow ratesand a high bacterial concentration percm 2 of effective filtration area. Thegrowth parameters, temperatures andmedia are adapted from the ASTM andHIMA methods.INOCULATED PRODUCT CHALLENGEWhen no deleterious effects fromthe product are revealed in the toxicitystudy, the organism is suspended directlyin the product to a concentrationresulting in greater than 1 x 107(CFU/cm 2 ) of effective filtration area. Asample of the challenge suspension istaken for titer and the test filters arechallenged at worst case conditions.The filtrate is collected and the totalvolume assayed by membrane filtrationto quantitate any passage of the challengeorganism through the test filter.Integrity testing (forward air diffusionand bubble point) is performed on eachfilter before and after the challenge.RE-CIRCULATING TECHNIQUEWhen toxicity or physical incompatibilitiesdirect, the product is re-circulatedthrough the test filters by peristalticpump for the duration of theprocess time. The filter and test apparatusare flushed with an appropriatesolvent to remove any residual productand the filter is challenged withthe organism at greater than 1 x 107per cm 2 of effective filtration area insaline lactose broth. The filtrate is collectedand assayed to quantitate anypassage of the challenge organismthrough the test filter. Integrity testing(forward air diffusion and bubblepoint) is performed on each filter beforeand after the challenge.CONTROLThe ability of a significant numberof organisms from the test challengesuspension to pass through a 0.45µmmembrane constitutes the positive control.It is verified concurrently withtesting by challenging a “standard”0.45 µm membrane with an aliquot ofthe challenge suspension.CONCLUSIONAlthough manufacturing a sterilewww.filtnews.com • August 2010 • 19product that is labile when exposedto heat, chemicals, and radiation, offersseveral challenges, filtration sterilizationis an industry-acceptedalternative. With careful considerationof manufacturing and productneeds, a validation plan may be developedby the product manufacturerwith help from an independent laboratoryor filter manufacturer. It is alsoimportant to remember that it is theuser (pharmaceutical or biologicalmanufacturer) that bears the responsibilityfor validating its filtrationsterilization process, which may include,not only microbial retentionbut also compatibility, extractables/leachables,and integrity testing.It is recommended to consult with anFDA reviewer when developing a validationplan. It may also be helpful toconsult with an independent contractlaboratory that performs filtrationsterilization validations.FNFor more information contact Nelson Labs:Tel: 1-801-290-7500 Fax: 1-801-290-7998Website: www.nelsonlabs.com