Evaluating Real Time Viability Detectors

By Darrick Niccum, senior global product manager-biotechnology, TSI Incorporated

Rapid microbiological methods (RMM) have been around for many years but have yet to make a significant impact on pharmaceutical manufacturing processes despite the advantages they offer in terms of cost savings and process improvement. The majority of RMM’s are laboratory-based instruments that significantly reduce the time to obtain quantitative, or qualitative, microbiological results when compared to traditional culture plate methods. Most of these techniques require the collection of sample that must be prepared for analysis by the RMM device. A relatively new RMM entry is optical spectroscopy, which analyzes aerosol particles for viability on a particle- by-particle, real time basis.

Real time aerosol optical spectroscopy instruments use laser-induced fluorescence (LIF) to determine if a particle is viable or inert. The operational theory is based on the fact that viable cell metabolites fluoresce when excited by ultraviolet light. The principal metabolites targeted by aerosol LIF- based instruments are tryptophan, NADH, and flavins (riboflavin). LIF instruments have been produced for more than 20 years and were originally developed for military and homeland defense applications. Only recently has this technology been adapted for use in the pharmaceutical industry.