Viable Particle Count By Using Settle Plate Method   
1.     Purpose:-                         

To determine airborne microbiological contamination in clean rooms by Settle Plate Method 

2.     Scope:-

It is applicable to following areas:

o   Liquid Injectable area (Production Department)

o   IV Infusion filling area (Production Department)

o   Sterility testing Suit (Microbiology Department)

3.     HSE Statement:-

Not Applicable.

4.     Responsibilities:-

                               i)      Manager Quality Control is responsible to ensure that procedure & formats are followed entirely as approved.
                             ii)       Microbiologist is responsible to perform the test.
                           iii)      Lab attendant is responsible to assist the officer microbiologist for the preparation of test materials and to take the plates to respective areas.
5.     Materials:-

       5.1 Petri plates (90mm)
       5.2 Soya bean casein digest agar (SCDA)
       5.3 Screw cap flask
       5.4 SS-Tray
       5.5 Hot plate and stirrer

6. Definitions:-

           6.1 Viable particle count: (Also referred as Total Air borne Aerobic Microbial
                              The recovered number of colony forming units (cfu) per unit volume of air.
          6.2 Settle Plate Method: -
                     This method is widely used to qualitatively asses the environments over
prolonged exposure times. Settle plates when exposed for four hours period can provide a limit of detection for suitable evaluation of aseptic environment.

Flow Chart:-

 8.0 Description:-
  8.1 Procedure:-
   8.1.1 Preparation of Settle plates:- Weigh desired amount of agar medium (e.g.; Nutrient agar or SCDA) in a screw cap flask. Dissolve agar medium in calculated volume of distilled water according to manufacturer’s
instructions. Tight the cap of the flask and autoclave the medium at 1210C for 15min Take clean and washed petriplates (90mm) and sterilize them in hot air oven at 2000C for 2 hours. Allow petriplates to cool at room temperature. Pour approximately 30ml molten and autoclaved agar medium cooled at 400C sterile petriplates. Allow agar medium to solidify. After solidification, incubate each petriplate in inverted position for 48-72 hours at
          32.50C Examine each petriplate for contamination after incubation. Contaminated petriplates should be
            disposed off Use only contamination free petriplates for the test. Mop each petriplate from outside with a clean duster dipped in 70% IPA and label according to sampling plan.
 8.1.11 Do not label the plate from the lid side. In case of mixing of lids, this may cause
           in misinterpretation of results. Place all the petriplates in a SS-tray properly mopped with 70% IPA and send to the desired area for exposure. During transportation, do not open the lid of SS-tray. Place the SS-tray in Pass Through of the area under UV light.    
8.1.2 Plate Exposure Open the SS-tray in controlled area and bring the petriplates out of it. Place the plates in appropriate defined positions. Lift the lid of petriplate and place it in downside up position on the stand. Leave the petriplate open for 4 hours. Close the petriplate after the time of exposure. Clean the traces of agar or condensation traces from the place where plates have been exposed with suitable disinfectant. Place the petriplates back in SS-tray and Place it in Pass Through. Transfer the SS-Tray to Microbiological Lab. During transportation, do not open the lid of SS-tray. Incubate each petriplate in inverted position at 32.5 + 2.50C for 48-72 hours along with an unexposed Petri plate mentioning as Negative Control. After incubation, record the results by using colony counter
8.2 Specifications:-
For each grade of controlled areas or clean rooms limits are given below.
Table: Limits* for Microbial contamination (CFU/ Plate for 4 hours)
Sr. No.
Grade / Class
Standard Limits(cfu/plate)
Alert Limits(cfu/plate)
Action Limits(cfu/plate)
 At Rest

In Operation
   At Rest

   At Rest


·         Limits are bacterial count. Mold or fungal count should be considered as zero.

 8.3. Frequency:-
 8.3.1 Each operating shift
 8.3.2 After shut down for a weak or more
  9. Records
  9.1 Aseptic Area Monitoring (SPM & SAS)- Ampoule and IV Infusion Filling Area

9.2 Aseptic Area Monitoring (SPM & SAS) Vial Filling Area
9.3 Area Monitoring of Sterility Testing Room

10 References:-
10.1 Guidelines on the Test Methods for Environmental Monitoring for Aseptic Dispensing Facilities, Produced by: A Working group of the Scottish Quality Assurance Specialist Interest Group, February 2004. (For All Classes at rest)
10.2 Sterile Production, World Health Organization). (For All Classes at Operational Condition)
10.3    EU Requirements,FDA Requirements, WHO Requirements on Viable Particle count
 10.4 United States Pharmacopoeia 35. 

11. Distribution:-

This SOP has to be distributed in below mentioned Departments:-

Sr. NO
Distributed to
Quality Control Department

Quality Management Department

12 Revision History:-
Date                                        Changes