Bacterial adhesion: considerations within a risk-based approach to cleaning validation

Pharmaceutical manufacturing processes are vulnerable to varying degrees of microbial challenge (hazard) quantifiable as microbial ingress, and microbial retention risks affecting raw materials and inputs to the final product. Control over these risks is exacted by both purposefully designed and incidental (or fortuitous) properties of the manufacturing processes. Within the manufacturing environment, equipment cleaning and hold processes are uniquely prone to microbial challenge yet paradoxically demonstrate the greatest potential for mitigation of these risks. Cognition of those components and contributing factors associated with microbial challenge are necessary to facilitate scientifically sound risk assessments. In the context of equipment cleaning and hold processes, risk assessments are necessary to identify and contrive conditions, which are truly worst case for the validation of the control of microbial challenge. A number of components contribute to the risk of microbial retention, yet the phenomenon of microbial adhesion to surfaces remains one of the most ubiquitous and perplexing. The dual purpose of this review is to primarily précis and provide in a single reference those multi-factorial features and variables contributing to bacterial adhesion, and secondly to provide a guide for interpretation of those considerations for integration into a risk-based approach to cleaning validation.