Biological Indicator for Steam Sterilization,Paper Carrier
»Biological Indicator for Steam Sterilization,Paper Carrier,is a defined preparation of viable spores made from a culture derived from a specified strain of Bacillus stearothermophilus,on a suitable grade of paper carrier,individually packaged in a suitable container readily penetrable by steam,and characterized for predictable resistance to steam sterilization.The packaged Biological Indicator for Steam Sterilization,Paper Carrier,has a particular labeled spore count per carrier of not less than 104and not more than 109spores.When labeled for and subjected to steam sterilization conditions at a particular temperature,it has a survival time and kill time appropriate to the labeled spore count and to the decimal reduction value (Dvalue,in minutes)of the preparation,specified by:
Survival time(in minutes)=not less than (labeled Dvalue)×(log labeled spore count per carrier -2);and
Kill time(in minutes)=not more than (labeled Dvalue)×(log labeled spore count per carrier +4).
Packaging and storage— Preserve in the original package under the conditions recommended on the label,and protect it from light,toxic substances,excessive heat,and moisture.The packaging and container materials do not adversely affect the performance of the article used as directed in the labeling.
Expiration date— The expiration date is determined on the basis of stability studies and is not less than 18months from the date of manufacture,the date of manufacture being the date on which the first determination of the total viable spore count was made.
Labeling— Label it to state that it is a Biological Indicator for Steam Sterilization,Paper Carrier;to indicate its Dvalue,the method used to determine such Dvalue,i.e.,by spore count or fraction negative procedure after graded exposures to the sterilization conditions;the survival time and kill time under specified sterilization conditions stated on the label;its particular total viable spore count with a statement that such count has been determined after preliminary heat treatment;and its recommended storage conditions.State in the labeling the size of the paper carrier,the strain and ATCCnumber from which the spores were derived,and instructions for spore recovery and for safe disposal of the indicator.Indicate in the labeling that the stated Dvalueis reproducible only under the exact conditions under which it was determined,that the user would not necessarily obtain the same result and that the user should determine the suitability of the biological indicator for the particular use.
Identification— The biological indicator organism complies substantially with the morphological,cultural,and biochemical characteristics of the strain of Bacillus stearothermophilus,ATCC No.7953or 12980,whichever is stated in the labeling:under microscopic examination it consists of Gram-positive rods with oval endospores in subterminally swollen cells;when incubated in nutrient broth for 17hours and used to inoculate appropriate solid media,growth occurs when the inoculated media are incubated aerobically for 24hours at 55to 60,and similar inoculated media incubated concomitantly at 30to 35show no evidence of growth in the same period.When examined under conventional biochemical tests for microbial characterization,it shows a delayed weak positive catalase reaction,it does not utilize citrate,propionate or hippurate,it reduces nitrate,but it does not liquefy gelatin,and it gives a negative result with the Voges-Proskauer test.Organisms derived from ATCCstrain No.7953show negative egg yolk and starch hydrolysis reactions,while those derived from ATCCstrain No.12980show positive reactions in both tests.
Resistance performance tests—
Dvalue— Proceed as directed for the relevant procedure for D Valueunder Biological Indicators—Resistance Performance Tests á55ñ.The requirements of the test are met if the determined Dvalueis within 20%of the labeled Dvaluefor the selected sterilizing temperature,and if the confidence limits of the estimate are within 10%of the determined Dvalue.
Survival timeand kill time— Follow the procedure for Survival Time and Kill Timein the section Steam Sterilization,Paper Carrier,under Biological Indicators—Resistance Performance Tests á55ñ.The requirements of the test are met if all of the specimens subjected to the steam sterilization for the survival time show evidence of growth,while none of the specimens subjected to the steam sterilization for the kill time shows growth.If for either the survival time test or the kill time test,not more than 1specimen out of both groups fails the survival requirement or the kill requirement (whichever is applicable),continue the corresponding test with 4additional groups,each consisting of 20specimens,according to the procedure described.If all of the additional specimens subjected to steam sterilization either meet the survival requirement for the survival time test or meet the kill requirement for the kill time test,whichever is applicable,the requirements of the test are met.
Total viable spore count— Proceed as directed for Total Viable Spore Countin the section Steam Sterilization,Paper Carrier,under Biological Indicators—Resistance Performance Tests á55ñ.The requirements of the tests are met if the log average number of viable spores per carrier is not less than 0.3log of the labeled spore count per carrier and does not exceed the log labeled spore count per carrier by 0.48.
Purity—
Presence of contamination by other microorganisms— By examination of the spores on a suitable plate culture medium,there is no evidence of contamination with other microorganisms.
Disposal— Prior to destruction or discard,sterilize it by steam at 121for not less than 30minutes,or by not less than an equivalent method recommended by the manufacturer.This includes a test strip employed in any test procedures for the strips themselves.
Auxiliary Information— Staff Liaison:David A.Porter,Ph.D.,Associate Director
Expert Committee:(AMB)Analytical Microbiology
USP28–NF23Page 258
Phone Number:1-301-816-8225