Early Detection of Microbial Contaminants in Cell-Based Products Using the Milliflex^® Rapid System Combined with a Selective Lysis Solution

Abstract

The Milliflex^® Rapid System is a proven automated ATP-based solution used for rapid bioburden and sterility testing. Combining membrane filtration, ATP bioluminescence and imaging, it provides microbial enumeration in significantly less time than traditional methods. Detecting microbial contamination in cell-based products remains a challenge due to filterability issues and interference from mammalian ATP. To address this, a sample processing method has been developed using a selective cell lysis solution and a free ATP removal enzyme effective at both low and high mammalian cells densities. The processing of Chinese Hamster Ovary (CHO) cells ranging from 106 to 107 cells/mL with lysis solution eliminates the mammalian ATP background in 15 minutes. This requires a ratio of 4 mL of lysis solution per mL of sample at 106 cells/mL or 9 mL of lysis solution per mL of sample at 107 cells/mL. CHO cells were inoculated separately with 6 microorganisms including Cutibacterium acnes ATCC 6919 and then processed with the lysis solution before enumeration with the Milliflex^® Rapid System. Results showed a rapid enumeration of the 6 microorganisms with good recovery according to the control.