PROTOCOL TO EVALUATE EFFICACY OF UV GERMICIDAL LAMP WITH KNOWN MICROORGANISM
OBJECTIVE
The objective of this study is to determine the efficacy of UV germicidal lamp of Laminar air flow and pass box with known microorganism. This ensure that the UV is effective enough to kill the microorganisms on exposure to defined period of time and gives the idea at when the UV light to be replaced.
BRIEF DESCRIPTION
The purpose of UV lamp used in Laminar air flow and pass box are for germicide activity of that environment. It is important to ensure that the germicidal effectiveness of UV lamp at given time during the test should produce reproducible result.
The study shall be conducted with 200 to 250 microorganisms per plate. These plates shall be exposed to UV lamp at defined places on the working platform for the given time intervals.
PURPOSE
The purpose of UV lamp used in Laminar air flow and pass box are for germicide activity of that environment. This shall be achieved by exposing plates containing viable microorganisms for different time intervals.
Exposure time: 1 Minute, 2 Minutes, 5 Minutes, 10 Minutes, 15 Minutes, 30 Minutes.
Location of Plate: 1.Rear – Left, 2. Rear – Right, 3. Front – Left, 4. Front – Right, 5. Centre.
Viable count: ________
% reduction: _________
PROCEDURE
PREPERATION
Prepare cell suspension of Bacillus subtilis containing approximately 1000 cells / ml.
Prepare Soyabean casein digest agar plates as per STP.
Using sterile glass spreader, spread 0.25 ml of cell suspension on the surface of Soyabean casein digest agar plates.
Expose these plates under UV lamp for defined time interval.
After exposure, cover the plates with lid and incubate at 37°C for 3 days.
Repeat the test for each time interval.
Keep one un-inoculated plate as negative control and one plate, which is inoculated but not, exposed to UV, as positive control.
From positive control evaluate No. of colony forming units as “Initial count”.
Count the No. of colony forming units for each exposed plate.
Calculate reduction in count after UV exposure.
ACCEPTANCE CRITERIA
There should be 99 % reduction in the viable count after UV exposure for 30 minutes.
