Comparative study of impaction and sedimentation in an aerosol chamber using defined fungal spore and bacterial concentrations

Biocontamination control is a very significant part of the manufacturing process of sterile drugs. Sterility is frequently monitored by active or passive air sampling measurements, but there are no specific rules as to how this is to be done. This study tested air sampling methods of active impaction and passive sedimentation under standardized conditions. Aspergillus niger (A. niger) and Staphylococcus aureus (S. aureus) were selected in this experiment to examine parallels, correlations and differences between the two methods. The results show that the number of colony forming units per plate (CFU/plate) was higher for A. niger in the active method, whereas for S. aureus it was higher in the sedimentation method. A high correlation coefficient was found between the impaction and sedimentation methods for A. niger. For S. aureus, depending on the culture media used and the time for passive air sampling, a larger number of CFU/plate was found than in active air sampling. This study concludes that active and passive air sampling can be used for monitoring the air in clean rooms. For fungal spore detection, the impaction is more efficient, as it is possible to sample a higher volume of air in a shorter period of time, whereas the optimal measurement methods for S. aureus depend on a number of factors.