Clean-Test self-contained biological indicator performance used to steam sterilization process validation.

Thiago José Pelissari, Heron Oliveira dos Santos Lima, Mirela Vanin dos Santos Lima


Clean-Test self-contained biological indicators are used to monitor steam sterilization cycles. Each biological indicator has a minimum population of 105 or 106 UFC bacterial spores of Geobacillus stearothermophilus ATCC 7953. The purpose of this work was to study the behavior of Clean-Test self-contained biological indicator used to monitor and validate steam sterilization systems, in relation to the incubation time (24, 48 hours and 7 days) and the performance of microbial resistance at different conditions of time, pressure and temperature. The analyses were performed starting with the evaluation of lots of biological indicators by determining the initial population (N0), determination of D value (decimal reduction time), determination of survival and death times for the microorganisms. Then  was studied the resistance performance  of the biological indicator Clean-Test at different exposure times, temperatures and pressure, as well as the evaluation and analysis of the relationship between incubation time and growth rate for periods of 24, and 48 hours 7 days. The behavior of biological indicator when the temperature and pressure were increased was inversely proportional to D value (microbial resistance). The lot behavior of positive biological indicators by the end of seven days of incubation indicated minimal results of 97%, satisfactory acceptability which is acceptable according to ANSI/AAMI/ISO 11138-1:(2006)because the lots of biological indicators tested met its requirements.




Biological indicator, Steam Sterilization, D-value.

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DOI: 10.14685/rebrapa.v2i1.45


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