RT Journal Article SR Electronic T1 Probable Scenarios of Process Contamination with Cutibacterium (Propionibacterium) acnes in Mammalian Cell Bioreactor JF PDA Journal of Pharmaceutical Science and Technology JO PDA J Pharm Sci Technol FD Parenteral Drug Association (PDA) SP pdajpst.2019.010710 DO 10.5731/pdajpst.2019.010710 A1 Angel L Salaman-Byron YR 2019 UL http://journal.pda.org/content/early/2019/12/13/pdajpst.2019.010710.abstract AB Mammalian cell lines constitute an important part in the manufacture of therapeutic proteins. A contamination-free operation of a mammalian cell bioreactor demands constant attention to details. Cutibacterium acnes, a slow-growing bacterium, is a common skin flora and often being associated with mammalian cell bioreactor contaminations. This paper reviews the literature published about such C. acnes contaminations and presents three hypothetical contamination scenarios based on the author's experience in the hope of fostering early detection of contamination events. Bioreactor process parameters such as unusual dissolve oxygen fluctuation, high levels of ammonia and microscopic examination have been identified as useful tools to detect slow-grower bacteria contamination.