Facility-based case study: A comparison of the recovery of naturally occurring species of bacteria and fungi on semi-solid media when incubated under standard and dual temperature conditions and its impact on microbial environmental monitoring approach

摘要

This study compared the recovery of naturally occurring micro-organisms on tryptone soya agar (TSA) and Sahouraud dextrose agar (SDA), when incubated under three different temperature conditions. The micro-organisms were sourced directly from a factory environment. The incubation conditions employed were 20-25°C, 30-35°C and a combination of each, termed dual temperature incubation, for a period of 5 days. The results demonstrated that TSA was the most effective medium for the primary isolation of both bacterial and fungal/yeast micro-organisms. Bacteria were recovered best at 30-35°C with human commensals providing the largest numbers, while fungi and yeasts showed best recovery at 20-25°C. The use of dual temperature incubation at 20-25°C for 3 days followed by 2 days at 30-35°C gave reduced recovery for both types of micro-organisms. The authors recommend that similar studies should be considered for all manufacturing facilities in order to determine the optimal incubation temperature regime for the recovery of local, naturally occurring species of bacteria and fungi which may present a threat to aseptic manufacturing areas. This process should be undertaken as part of an overall risk assessment for the establishment and maintenance of a viable environmental monitoring programme and may also be relevant to the incubation conditions employed in process simulation studies.