DIAGNOSTIC DISCS 100 discs Code: DD 503
1000 discs DD 5031
for the identification of Streptococcus pneumoniae
Purpose and usage:
OPTOCHIN diagnostic discs are used for simple presumptive differentiation of Streptococcus pneumoniae from other viridans streptococci.
The test is based on sensitivity of Streptococcus pneumoniae strains to optochin (ethylhydrocuprein hydrochloride). On the contrary, viridans streptococci are remarkably resistant to optochin.
Inoculate densely and evenly blood agar plate with the tested strain (use a dense inoculum). Put OPTOCHIN disc by aseptic technique on the surface of the plate. Incubate 24 hours at 37°C under a higher tension of CO2.
If you expect large numbers of pneumococci in the tested material you can use OPTOCHIN disc for presumptive identification of S. pneumoniae already in the primary culture.
NOTE: For better evaluation of results we recommend to use suspension of the tested strain in saline (2-3 colonies in 2 ml of saline) for inoculation of blood agar plates. Place OPTOCHIN disc on the plate after suckling off the remaining liquid and after drying the inoculum.
If an inhibition zone develops after incubation, measure its diameter:
Inhibition zone (mm):
Result: > 14 Streptococcus pneumoniae
< 14 S. pneumoniae is to be confirmed by the bile-solubility test
0 Viridans streptococci other than S. pneumoniae
1. OPTOCHIN discs are designed for laboratory use only.
2. Discs should be stored in a dark place at +4°C and should not be used beyond the expiration date shown on the packing.