Probable Scenarios of Process Contamination with Cutibacterium (Propionibacterium) acnes in Mammalian Cell Bioreactor

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 is often 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 fluctuation in dissolved oxygen, high levels of ammonia, and microscopic examination have been identified as useful tools to detect slow-growing bacteria contamination.