Effectiveness and Recovery rate of Microorganisms on SCDA plate of Settle Plate in Environmental Monitoring

Environmental Monitoring Programme is essential for evaluation of clean room contamination by known with different techniques are Settle plate , Air Sampling ,Contact plate method. In that Settle plate method is the most important one for determine the contamination levels in clean grades.

Settle Plate Method:

In Environmental Monitoring programme Settle Plate method is also known Passive Air Monitoring . In this method Soya been Casin Digestive Agar(SCDA) 90 mm plates are used for sampling . Passive Air Sampling is performed in clean room grades i.e. A,B,C,D exposure of SCDA Plates for 4 hrs .after exposure SCDA Plates need to incubate at 20- 25 degree centigrade for 72 hrs after incubation Periods SCDA plates transferred into 30-35 degree centigrade for 48 hrs. After incubation period count the number of colonies using by colony counter .

Ex: Location: SPM 16 – 47 cfu /4 hrs

Effectiveness of recovery rate from SCDA Plates in different time intervals:

In this study we need to know the how correlation between the hours of exposure and recovery rate of organisms in clean room monitoring . Initially study was conducted for ten different location in controlled Microbiology laboratory area, SCDA plates( 90mm) expose in particle location in controlled area in different time interwall up to 2 hr, 4 hr, 6hr, and 8 hrs ,after exposure these plates incubated in incubator at 20-25 ⁰c for 72 hrs after transfer SCDA plates into 30-35⁰c for 48 hrs .After incubation count the colonies under colony counter.

Microbiology Laboratory Controlled Area Grade-C Location	02/06/20  Cfu/2 hr	03/06/20  Cfu/4 hr	04/06/20  Cfu/6 hr	04/06/20  Cfu/8hr
PSP01	25	38	29	18
PSP02	26	39	27	19
PSP03	36	42	35	26
PSP04	38	41	34	27
PSP05	18	31	27	21
PSP06	35	42	28	15
PSP07	34	39	29	21
PSP08	28	34	24	11
PSP09	29	31	22	13
PSP10	19	28	21	9
Alert Level	45	45	45	45
Action Level	50	50	50	50

Settle Plate Monitoring Different Time Intervals in Grade-C area of Microbiology Laboratory

Correlation of Recovery rate Colonies Vs Time of Exposure of Settle Plate Monitoring

Summary and Conclusion

From the above data summarises that the number of colonies are gradually decreases from 4 hrs exposure to 8 hr exposure due to over time exposure of SCDA plates leads to dryness and formation of a thick layer on the plate inhibits the growth of colonies and get false positive result. The above conclusion is clearly states that 2 to 4hr time best form environmental monitoring in clean rooms and controlled environment.