Rapid Microbiological Methods for a New Generation
These are exciting times, as 19th-century microbiological methods make way for rapid detection, quantification and characterization technologies.
By Michael J. Miller, Ph.D., Senior Research Fellow, Eli Lilly and Co.
Optical spectroscopy and instantaneous detection
Optical spectroscopy measures the interactions between light and the material being studied. Light scattering is a phenomenon in which the propagation of light is disturbed by its interaction with particles.
In a Mie scattering particle detector, airborne particles intersect a light beam emanating from a laser diode. If the air is free of particles, a “beam blocker” at the center of the first convex lens stops this laser beam. If the air contains particles, they will scatter the laser beam and cause part of the light to deviate at an angle from the incident beam. This scattered light will be collected by the second lens and focused onto a photo detector, which converts the light intensity to an electrical signal. This is the basis for a novel, instantaneous and continuous microbial detector, currently in development at BioVigilant Systems (Tucson, Ariz.).
The technology was originally developed to detect potential bioterrorism agents such as anthrax spores, but is now being adapted to the pharmaceutical industry’s unique needs. The platform uses a Mie scattering particle counter with effective detection of particles within the 0.5 to 20 µm range. The detection of biological particles is based on the autofluorescence of cellular targets including NADH and riboflavin, under UV laser with a wavelength of 405 nm. The company will be working on a method to capture microorganisms after analysis for further processing, such as microbial identification.
In short, these are very exciting times for microbiology, and, as more alternatives become available, more pharmaceutical microbiologists will embrace rapid detection, quantification and characterization technologies. No doubt Fanny would be proud of these worthy successors to agar cultivation.
About the Author
Michael Miller, Ph.D., is Senior Research Fellow in the Manufacturing Science and Technology (MS&T) function at Eli Lilly and Co. (Indianapolis). He is responsible for providing technical leadership in microbiology and sterility assurance within Manufacturing, Quality, Engineering, and Product Development. He is also accountable for leading Lilly’s corporate initiatives for Process Analytical Technology (PAT), barrier isolation technology and rapid microbiological methods. Previously, he held numerous business development, Quality and R&D leadership roles at Bausch & Lomb and Johnson & Johnson.
Dr. Miller has authored over 60 technical publications and presentations in the areas of rapid microbiological methods, PAT, ophthalmics, disinfection and sterilization, and has served as Chairperson for numerous rapid microbiological methods technical conferences in the United States and Europe. Most recently, he was the editor of the Encyclopedia of Rapid Microbiological Methods, a three-volume reference co-published by the PDA and Davis Healthcare International Publishing.
Dr. Miller holds a Ph.D. in Microbiology and Biochemistry from Georgia State University (GSU), a B.A. in Anthropology and Sociology from Hobart College, and has served as an adjunct professor at GSU and the University of Waterloo School of Optometry.
GSK: Using Rapid Detection for PAT-worthy Product Release
A microbial monitoring milestone was achieved in 2004 when GlaxoSmithKline announced that it had been granted FDA approval to use ATP bioluminescence technology to release a prescription nasal spray product in its Parma, Italy plant. This was the first time a drug maker had used a rapid detection technology to release product under FDA’s Process Analytical Technology (PAT) initiative.
GSK sought approval based on FDA’s comparability protocol approach; it was granted in just 19 days, reported Dr. Paul Newby, team leader, Pharmaceutical Microbiology for GSK, reported at last fall’s Pharmaceutical Microbiology Interest Group gathering in London.
GSK Parma uses a novel two-tier release strategy for the non-sterile product: first, a presence/absence test using Pall Life Sciences’ (East Hills, N.Y.) Pallchek ATP bioluminescence system (at right); then, if contamination is present, further conventional assessment to determine its level and identity. The approach has allowed GSK to reduce its release time for the product from several days to 24 hours, said Newby. The approval was noteworthy for the fact that FDA had previously stated publicly that it would not accept such a strategy, Newby noted.
ATP bioluminescence is also being tested by Bristol-Myers Squibb in France to obtain immediate readings for monitoring Water-for-Injection system contamination, Dr. Eric Bagur, bacteriological quality control manager of BMS, France, recently reported. Several years ago, GSK gained European approval to use another rapid method, solid-phase cytometry, using the Chemscan RDI by Chemunex (Princeton, N.J.), for rapid testing of pharmaceutical-grade water.