Trend Analysis of Microbiological Samples within Isolators

Introduction
On the occasion of the installation of new isolators in our institution during summer 2023 and the official release of the new 2023 Good Preparation Practices (GPP), it was decided to study and compare the microbiological sampling frequency recommended in the GPP with the processes in place in our hospital.

Objectives
The objectives consist of conducting a trend analysis and defining a new microbiological sampling frequency.

Materials and Methods
The initial four-week phase involves strict implementation of GPP recommendations. Air samples by sedimentation agar are taken at each workstation in the morning and in the afternoon, along with operators’ glove imprints at the end of work session. On top of that, contact samples are taken once a week at 10 critical points designated by the supplier (lower tray of sas1, upper tray of sas 2, sas 1 door seal, workbench near the air vent, upper shelf, workbench near the trash bin, workbench near the opening to the product sas, inside of the plexiglass window, sas product grating, refrigerator container). Finally, a monthly sample is taken with the air sampler. After that, sampling frequencies are adjusted based on the results obtained. Samples are taken in accordance with the Association for Safety and Economic in Pharmacy (ASPEC) directives.

Results
Results of aerobiocontamination indicate a concentration lower than 1 colony forming unit per cubic meter (cfu/m3), while it is lower than 1 cfu/4 hours for sedimentation. Concerning contact agar plates, results are also lower than 1 cfu/plate, except for one positive sample in the product exit airlock. Observed results comply with glove imprints, with less than 1 cfu/glove. Consequently we settled to adjust sampling by conducting one sedimentation on each side of the isolator per day, one agar plate per pair of gloves at both workstations per day, while maintaining the same frequency for contact agar plates and aerobiocontamination. Once the new method implemented, no more contamination was observed during the testing period.

Discussion/Conclusion
The revaluation of microbiological sampling practices allowed us to update our microbiological analysis frequency by spacing out some samplings to limit agar consumption while ensuring compliance with ISO5 (Class A) standards inside the isolator. It was therefore set to conduct our samplings according to the following schedule: monthly for aerobiocontamination, weekly for the 10 points for contact agar plates, daily for glove samplings at each workstation, and sedimentation as a daily sampling of up to 4 hours at each workstation. This also led us to implement aerobiocontamination within our isolators.

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