Application of Biofluorescent Particle Counters for Real-Time Bioburden Control in Aseptic Cleanroom Manufacturing

Abstract

This experimental study examines the use of a real time viable particle counter in pharmaceutical cleanroom operations under ISO class 8/Annex 1 Class C ‘in operation’ conditions. The used measuring system, a Biofluorescent Particle Counter (BFPC), continuously detected particles >1.0 µm as well as microbe carrying (viable) particles (MCPs). In addition, classic air samplers for the evaluation of Colony Forming Units (CFU) were installed to enable a comparison of counter-provided values with classic, agar-based methods of microbial air sampling required by regulatory guidelines. A test room comparable to typical cleanrooms in the pharmaceutical industry was operated under three different air change rates (ACR). At these ACRs, the operators wore three different garments. With test repetition, 18 experiments were conducted simulating different pharmaceutical process conditions. The results show correlations of measured particles to MCPs and MCPs to CFUs. Furthermore, albeit an industry-wide used and regulatory accepted minimum ARC value of 20 h−1, the study results indicate that an ACR of 10 h−1 is capable of keeping cleanrooms within regulatory limits for particles and CFUs, and thus provides the opportunity to save energy for cleanroom operations. The implementation of real time viable particle counters can be used to achieve a quality advantage for ISO class 8 cleanrooms for a continuous, documented control of the cleanroom status, and thus enable a reduction of ACRs with the aim of energy saving. Further long-term studies should validate this.