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Microbial data deviations occur when the results of microbial tests fall outside of the product specifications or acceptance criteria. These deviations are also known as “out-of-specification” or “out-of-limit” results.
The purpose of a microbiological data deviation investigation is to identify the root cause, take corrective and preventative actions (CAPA), and demonstrate that the actions are effective. The investigation should be based on an SOP.
Investigating a Microbial Deviation
Identification
The type of investigation may require identifying the organism to the genus and/or species level, or to the species level and sometimes the strain level.
Sampling
Sampling can be imprecise due to the uneven distribution of microorganisms in the environment.
Test Methodology
There is inherent variability with microbiological test methods.
State of the microorganism: The state of the microorganism can vary depending on the growth phase.
Some tools that can be used in an investigation include: Pareto Charts, Fishbone Diagrams, The 5 Whys, Failure Mode and Effects Analysis (FMEA), and Risk Matrices.
In the pharmaceutical industry, a major deviation can affect a product’s quality, safety, or efficacy, but may not have a direct impact on patients.
A minor deviation affects a utility, equipment, material, component, or documentation, but does not affect product quality.
