FDA is aware of a report of Leptospira licerasiae contamination in cell cultures (see Chen, Bergevin, et al. 2012). There is no indication that this bacterium ultimately contaminated either the finished drug substance or drug product. This bacterium has been found to pass through 0.1 µm pore size rated sterilizing-grade membrane filters. While this specific species was the identified contaminant in this case, other Leptospira species also are capable of passing through 0.1 µm pore size rated filters (see Faine 1982). Compendial microbiological test methods typically used in association with upstream biotechnology and pharmaceutical production are not capable of detecting this type of bacteria. Whether this apparently rare contamination risk may be more widespread is unknown, and we are sharing this information so that manufacturers can consider whether this hazard may be relevant to their operations.
Leptospira are Gram-negative aerobic spirochetes that are flexible, highly motile, and spiral-shaped with internal flagella. The bacteria measure 1μm in diameter and 10-20 μm in length. Leptospira are obligate aerobes that use oxygen as the electron receptor and long-chain fatty acids as a major source of energy. While some of the Leptospira are harmless fresh-water saprophytes, other species are pathogenic and can cause leptospirosis, a significant disease in humans and animals (Ricaldi, Fouts, et al. 2012; Matthias, Ricaldi, et al. 2008; Bharti, Nally, et al. 2003).
Based on current information, Leptospira contamination does not appear to occur frequently, and purification steps that follow cell culture in a typical biotechnology operation would be expected to prevent carryover to the finished drug substance. Testing of bulk drug substances produced in the reported cases did not detect the Leptospira species, and no evidence of deleterious effects on in-process product were observed in the known case study. However, we are providing this communication to alert manufacturers that these types of bacteria can potentially:
Penetrate sterilizing-grade membrane filters
Be present in the manufacturing site environment
Impact in-process production (e.g., production yields, impurity levels, process performance)
Go undetected due to the limitations of current compendial bioburden tests in detecting this microbial genus
As a general principle, manufacturers should use sound risk management and be aware of unusual microbiota reported in the literature that may impact their manufacturing processes (e.g., cell culture biotechnology, conventional sterile drug manufacturing).
Manufacturers should assess their operations, be aware of potential risks, and apply appropriate risk management based on an understanding of possible or emerging contamination risks (see section 18.3 in ICH guidance for industry Q7 Good Manufacturing Practice Guidance for Active Pharmaceutical Ingredients). As appropriate, preventive measures should be implemented during the product and process lifecycle.
To illustrate, if leptospiral contamination is considered possible, or has occurred, risk mitigation procedures and practices for this microorganism should include at least the following:
(1) Review of available published articles from the scientific literature and technical reports by related industry organizations that may provide further understanding on how to mitigate this contamination hazard.
(2) Use of molecular or nonconventional microbial monitoring methods at appropriate intervals to detect microbial flora that may exist in processing steps or in the immediate environment, but are not readily detected by current routine methods. Such expanded testing should be used to modify the strategy (e.g., timing, frequency, types of tests) of detection and control in the event of newly identified risk posed by the viable, but not easily cultured, microorganism.
