The effectiveness of Settle plate technique which is employed for monitoring of bio load in manufacturing area mainly depends upon the sampling locations chosen during the study.
The selection of sampling locations should be in such a way that the entire study which is carried out reflects the true microbiological quality of the area under study.
The sampling location selected should be giving maximum number of air born particles on the exposed media surface in the specified exposure time period.
Presently in the Settle plate technique, plate exposure locations are mainly the air outlets where maximum recovery of bio load is expected. A plan has been designed in various locations to find out the maximum recovery of bio load. Following are the locations identified (which ever is applicable),
- AHU inlets
- Return air duct
- Near to the drain trap
- Personnel entry and exit ways
- Material entry and exit ways
- Pass box
A pair of culture media plates namely Soybean casein digest agar and sabouraud dextrose agar shall be exposed at each of the above listed sampling location for a period of 4 hours. These Soybean casein digest agar and sabouraud dextrose agar plates shall be incubated at 37°C± 2°C for not less than 3 days and 22°C ±2°C for not less than 5 days respectively to allow the growth of the microorganisms.
This entire study shall be carried out for five working days to optimize to get the trend. Based on the trends of results, evaluation of the various sampling locations chosen shall be done for suitability in Settle plate technique as a regular sampling location.