ENVIRONMENTAL MONITORING BY SETTLE PLATE METHOD
OBJECTIVE: To lay down a procedure Environmental monitoring by settle plate method.
SCOPE: This SOP is applicable for Environmental monitoring by settle plate method of this organization.
RESPONSIBILITY:
Quality control – Executives
Quality control – Officer (microbiologist)
ACCOUNTABILITY: Quality control – Head
PRECAUTIONS :
Glass wares employed for sampling should be cleaned as per the SOP, autoclaved as per SOP and dried.
Media should be autoclaved and cooled, up to 450C to 500C properly before pouring into Petri plates.
Aseptic measures should be adopted during plate pouring operations.
Solidify the media under LAF before subjecting the plates for preincubation.
Contaminated plates obtained after preincubation should be rejected and only fresh Plates without contamination should be employed for exposing.
Immediately close the lid of Petri plates as soon as the exposing operation is over followed by incubation.
Add 10% glycerol to the media before sterilization.
Record of the count should be made properly in an authorized format only.
MATERIALS & EQUIPMENTS REQUIRED
MATERIALS:
SCDA
WFI, 70% v/v IPA, Micropipette (1000ul) and micropipette tips.
Glycerol 10%.
EQUIPMENTS:
Colony counter
Lab. Incubator and BOD Incubator.
Autoclave & hot air oven and LAF unit.
PROCEDURE
Wear clean Lab coat and cap wear hand gloves rinsed in 70% IPA during media Preparation and plate pouring method while, sterile dress with sterile hand gloves should be worn during plate exposure operations.
Prepare SCDA agar media required for plate exposure as per SOP Adjust pH and autoclave the prepared media as well as the Petri plates at 1210c for 15 min (as per SOP)
After autoclaving, dry the Petri plates in hot air oven at 600 C for 2 hr. and allow cooling, similarly, cooling the media to 45◦c before proceeding for the Plate pouring in MLT room under LAF Unit.
Pour approx. 16-18 ml of liquefied SCDA agar media cooled to 450c in all Petri plates required as per the exposure location
Cover the Petri plates and allow the poured media to solidify under LAF. After solidification, pre-incubate all media containing Petri plates in a laboratory incubator at 32.50C -2.50C for 18- 24 hours in inverted position for detecting any contamination during plate pouring operations.
Following incubation, examine all Petri plates for microbial growth. Petri plates without Contamination following pre incubation is selected for plate exposure Operation.
Before exposure label all the plates as exposure area/ location number/ date of exposure/ sign and expose the plates according to location chart
make all preincubated media containing plates in a S.S. container along with S.S. Plates holder (mopped properly with 70% IPA) and carried to the location of exposure in Classified & Unclassified Area. (Class D)
Expose the Petri plate at each location by removing the upper lid of the Petri plate and placing the media containing part on the plate holder. Expose the media for 4 hours.
Exposure for all other sampling locations should be carried out in similar manner.
After expose the media for 4 hours close the Petri plate’s lids, collect all Petri plates in same S.S container and bring the exposed plates to Laboratory.
If Working of Plate exposing Break down the plates, then Immediately do the proper sanitizing with Disinfectant and note down the no. of location and Next plate Exposing on basis of planning and cover the location.
Incubate all exposed Petri plates in laboratory Incubator at 200C-250C for 72 hours for fungal and at 30ºC-350C for 48 hrs. for bacterial.
After incubation, count the number of colonies forming units (CFU) per plate per location with the help of colony counter.
FREQUENCY: Monthly. (All area covers in monthly plan)