Case Study of a New Growth-Based Rapid Microbiological Method that Detects the Presence of Specific Organisms and Provides an Estimation of Viable Cell Count

Published In “Encyclopedia of Rapid Microbiological Methods”, vol 4. Editor Michael Miller 2013, PDA Bethesda, MD. DHI Publishing River Grove. IL.


Chapter  Highlights

The BioLumix Rapid Microbiological System is capable of performing testing with a similar outcome to USP <61> (USP, 2009a) and <62> (USP, 2009b) simultane­ously on a single platform faster than the conventional USP methodology. The automated growth-based system detects microbial growth, provides an estimation of viable cell counts (total aerobic count, yeast and mold, bile tolerant Gram-negatives), and identifies the absence of specified groups of microorganisms. The novel BioLumix Optical System using ready-to-use vials provides faster results, labor savings, automation, and connectivity. The streamlined testing design and rapid results lead to reduced material-holding time for faster product and raw materials release. The BioLumix System is capable of analyzing tablets, capsules, powder, liquid and viscous material without any product interference. BioLumix offers a comprehensive range of micro­biological tests for raw materials, in-process and finished products, as well as process water. Environmental monitoring (e.g., detecting micro-organisms on surfaces) is also performed easily by inserting the swab directly into the assay vial. Early warning of contaminated samples, as well as sample release informa­tion, could be automatically communicated through your intranet, significantly improving your company’s efficiencies. The software is 21 CFR Part 11 compliant and a Drug Master File (DMF) is on file with the FDA.

Industry Needs

Effective microbiological monitoring of pharmaceutical manufacturing processes is a necessary step to meet industry standards of product quality.  From a microbiology perspective, the industry should apply Quality Risk Management (QRM) principles in order to design a process to prevent contamination of product while investigating ways that correct contamination events.  QRM is an important part of science-based decisions that are essential for the quality management of pharmaceutical manufacturing.

Similarly, the FDA’s cGMPs for the 21st Century: A Risk-Based Approach, states “that using a scientific framework to find ways of mitigating risk while facilitating continuous improvement and innovation in pharmaceutical manufacturing, is a key public health objective, and that a new risk-based pharmaceutical quality assessment system will encourage the development of new technologies, such as Process Analytical Technology (PAT), to facilitate continuous manufacturing improvements via implementation of an effective quality system”.

In 2003 the FDA introduced the PAT initiative to “encourage the voluntary development and implementation of innovative pharmaceutical manufacturing and quality assurance.” PAT is comprised of four components: data analysis, process analytical tools, process monitoring, and continuous feedback. The quality-by-design aspect of PAT should reduce cycle time thus reducing the wastes of waiting and excess inventory already identified by lean manufacturing.

BioLumix Can Help Meet Industry Needs

Standard microbiological methods require up to seven days to complete.  At every point where microbial testing is carried out (raw materials, work-in-progress, or finished products) batches may be held in quarantine before they are pronounced ready to move to the next product stage.  Waiting for microbial results can tie up working capital and often results in storage expenses and delays in supplying products to the market. Essentially, inventory stays on the floor instead of going out the door to the customer and/or patient population.

The BioLumix Instrument is an example of a new generation Rapid Microbiological Method (RMM).  The BioLumix System is based upon detection of changes in color or fluores­cence due to microbial metabolism in liquid medium within a novel two-zone test vial. An optical sensor monitors these changes within the vial’s reading zone, which is physically separated from the incubation zone. This two-zone approach prevents masking of the optical pathway by product or microbial turbidity and, therefore, eliminates product interference.

The BioLumix System can be used to perform testing for total aerobic count, yeast and molds, and Gram-negative bile-tolerant bacteria as described in USP <61> (USP, 2009a).  The system can also detect objectionable organisms such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Salmonella according to USP <62> (USP, 2009b). Each of these assays can be simultaneously performed using the same instrumentation. The sensitivity of the BioLumix System is a single viable cell per sample vial; when a single cell replicates to a specific detection threshold level, a positive response is recorded (detection time (DT)). The threshold level is ~100,000 cells/mL for bacteria and ~10,000 cells/mL for both yeast and molds. BioLumix uses the dilute-to-spec protocol, which requires diluting the sample to product release specifications or in-process action levels. If growth is detected, the sample fails; if there is no detection, the sample passes (i.e., the counts are below the specification limit).


Summary of Data from the Chapter

  1. Side by side growth comparison to USP<61> was shown for Total Aerobic Counts, Yeast & Molds, and for Gram Negative Bile-Tolerant organisms.
  2. Specificity using Inclusivity and Exclusivity testing was demonstrated for the BioLumix system.
  3. The Limit of Detection was demonstrated using target organisms.
  4. Robustness of the system was demonstrated using the following parameters:  effect of instrument temperature, effect of sample size, and effect of media volume in BioLumix vials.
  5. Ruggedness of the system was demonstrated using the following parameters:  effect of the analyst, effect of reagent lots, and effect of different instruments.



  1. United States Pharmacopeia (USP) (2009a), Chapter <61>, Microbiological Examination of Nonsterile Products: Microbial Enumeration Tests, The National Formulary, Rockville, MD, The United States Pharmaceopeial Convention.
  2. United States Pharmacopeia (USP) (2009b), Chapter <62>, Microbiological  Examination of Nonsterile Products: Tests for Specified Microorganisms, The national Formulary, Rockville, MD, The United States Pharmaceo­peial Convention.

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