25º Congresso Brasileiro de Microbiologia

25º Congresso Brasileiro de Microbiologia

ResumoID:2499-1

Área: Microbiologia Geral ( Divisão H )

INFLUENCE OF THE VOLUME OF A STERILIZING SOLUTION OF BACILLUS STEAROTHERMOPHILUS IN THE STERILIZATION PROCESS UTILIZING PLASMA STERILIZER

Cristiane Mezaroba (Cisa); Tania Bonfim (UFPR)

Resumo

Abstract The Plasma Sterilizer utilizing a chemical solution and gas plasma technology. There is suited to the sterilization of heat and moisture-sensitive instruments. The efficacy of the process is verified by a sterility assurance level (SAL) of at least 10^(-6) B. stearothermophilus spores. Objective The purpose of this study was to verify the influence of the volume of the sterilizing solution in the B. stearothermophilus sterilization process utilizing the Plasma Sterilizer. Materials and Methods Materials The sterilizing equipment was Cisa model SPS 640. The mixture used for the sterilization cycle was composed of peracetic acid (min 15%), hydrogen peroxide (min 23%), acetic acid (max 16%) and stabilizer (q.s.p. 100%). Suspensions of spores of B. stearothermophilus ATCC 7953, 10^8 spores/ml were used and inoculated in 7x25 mm stainless steel polished strips. Tripic Soy Agar (Oxoid) was culture media. Prepare of the strips The strips were dipped initially in HCL (1:1) for 30 min, rinsed and dried and sterilized at 121,1°C for 15 min, after were inoculated with a 0,1 mL suspension of 10^8 spores of B. stearothermophilus, dried in a biological hood at room temperature, put into sterilized test tubes and wrapped with Tyvek®. Test All the critical process parameters except the volume of the chemical solution has been fixed in the cycle. Tests strips are loaded in the chamber. After treatment, test strips submitted to the sterilizing cycle and positive control were transferred into tubes filled recovery solution with glass beads and was macerated in vortex, submitted for heat shock procedure and a dilution series. 1 mL from this dilution was pipetted into two Petri dishes, TSA agar was poured and incubated at 55-60 °C. After 48 hours the plates were counted. Results and Discussion Volume(ml) Initial 0,25; 0,5; 1; 1,5; 2 Inicial Log (No) 2,86E+07; 1,54E+06; 1,40E+07; 1,40E+07; 1,10E+07 Log trailing (N) 2,13E+05; 9,30E+01; 1,29E+01; 1,00E+00; 1,00E+00 Difference (NRD) 2,13; 4,22; 6,04; 7,15; 7,04. The Number of decimal reductions (NRD) was calculated by the equation NRD = Log No – Log N, where, No is the initial number of spores (positive control) and N is the number of surviving spores. Conclusion It was possible to verify the influence of the volume of the sterilizing solution in the B. stearothermophilus sterilization process utilizing the Plasma Sterilizer. The log reduction is higher as larger is the volume of the sterilant injected.

Palavras-chave: Plasma Sterilizer, Bacillus stearothermophilus, sterilization process

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