Procedure to carry out Optochin test:
o Streak a blood plate with the organism to be tested.
Place an optochin disc in the centre of the inoculum.
Incubate at 35-37°C for 18-24h in 5% CO2.
Examine for zones of inhibition.
Positive result zone
of inhibition of ≥5mm radius from the edge of the disc eg. Test organism is S. pneumoniae.
Negative result no zone
of inhibition, or a zone ‹5 mm radius from the edge of the disc eg. Test organism is not S. pneumoniae.