SOP on Testing Efficacy of Disinfectants.
Objective: To lay down a procedure for testing efficacy of Disinfectants.
Scope : This SOP is applicable for testing of efficacy of disinfectant solutions used in microbiology laboratory and production area.
Responsibility
Microbiologist
Head-Microbiology
Accountability
Head-Quality Control
Head-Quality Assurance
Procedure
Prepare Culture suspension of Escherichia coli ATCC 8739, Candida albicans ATCC 10231 Pseudomonas aeruginosa ATCC 9027, Bacillus subtilis ATCC 6633 and a common isolate of environment as per SOP.
Prepare stock solution of the above culture suspensions to obtain a concentration of at least 1000 organisms per ml.
Prepare 1000 ml of the required concentration of disinfectant solution in sterile water for injection or purified water as per SOP.
All activities shall be carried out under Laminar Airflow bench.
Dispense 100 ml of disinfectant solution prepared into a sterile container.
Inoculate it with 1 ml from dilution containing 1000 CFU/ml (or 0.1 ml of 100 CFU).
Give a contact time as per the table for different disinfectants.
After the elapse of Contact time, filter the disinfectant solution through a filtration unit having 0.45 m sterile membrane filters.
Rinse the membrane with 3 x 100 ml of Sterile 0.1% Peptone water.
Transfer the membrane onto Soyabean casein Digest Agar for Bacteria and Sabouraud Dextrose Agar for Candida albicans.
Incubate the plates for 5 days at 30-35 0C for Bacteria and 20-25 0C for Candida albicans.
Calculate the log of initial count and the final count. Subtract the log of final count from initial to get log reduction.
Record the details.
Run a negative control by filtering the disinfectant solution only followed by rinsing with 3 x 100 ml of 0.1% Peptone water and placing the membrane onto respective agar plates.
Table for Disinfectants, Contact Time and Effective Concentration.
| Sr.No SNo | Disinfectant | Contact Time
(in min) |
Effective Concentration (%) |
| 1 | Sterillium | 5 | undiluted |
| 2 | IPA | 10 | 70 |
| 3 | Savlon | 10 | 2.5 |
| 4 | Combatan DS | 5 | 1 |
| 5 | Protasan DS | 10 | 1 |
| 6 | Triple 100 | 10 | 1 |
| 7 | Lyzol | 10 | 1 |
| 8 | Domex | 10 | 1 |
Frequency: Every new lot shall be tested for disinfectant efficacy.
List of Annexure:
Disinfectant Efficacy Test Report – Annexure – I.
Reason for revision
Not Applicable due to first version
Abbreviations:
SOP : Standard Operating Procedure
No : Number
IPA :Isopropyl Alcohol
CFU : Colony forming Unit.
Annexure – I
Disinfectant Efficacy Test Report
Serial dilution of micro- organism
A.R No:
Date of test : Date of observation:
Media lot No : Date of prep. :
Observation:
| Name of organism | Serial dilution using 0.9% saline solution. | |||||
| 1:100 | 1:1000 | 1:10000 | 1:100000 | 1:1000000 | 1:10000000 | |
Incubation temperature:
For Bacteria: 30 to 35°C For Fungus : 20 to 25° C
EFFICACY OF DISINFECTANT
Name of disinfectant: Media Lot No :
Concentration : Date of prep. :
Date of test : Date of observation:
Observation table:
| Sr.No | Name of organism | Initial count | Log of Initial Count | Count observed after contact time in cfu/ml | Log of Final Count | Log Reduction=Log(Final count)-Log(initial Count) |
| Negative Control | Positive Control | ` | ||||
Remarks: The bactericidal/fungicidal activity is achieved within…………min at concentration of ______________________________________.
Done by: Checked by:
Date: Date:
