The results of bioburden testing provide manufacturers with a ‘snapshot’ in time but the problem is that the situation can change without warning. A manufacturer could be presented with a bioburden result that fails the action limit seemingly for no apparent reason. Due to the nature of microbiological testing, the bioburden result may be discovered only after the medical device has been sterilised. So just what are the implications for the manufacturer of a failed medical device bioburden result, given that most sterilisation methods are validated on an overkill approach, having a high level of conservativeness built in?
Bioburden testing determines the microbiological loading of a medical device that is a combination of the microbial content of raw materials, storage conditions, manufacturing environment and cleanliness, manufacturing process steps and personnel. As long as the bioburden result remains consistent and within defined limits, it indicates there has been no change in any aspect that could lead to increased microbial contamination, especially as the bioburden represents the microbial challenge to the sterilisation process. To comply with the standard, ISO 13485 Medical devices – Quality management systems – Requirements for regulatory purposes, all non-conformances must be investigated, and this includes bioburden results. If the issue is serious enough or continual bioburden excursions are noted, this may require converting to a CAPA (Corrective Action and Preventive Action).