2.3. Antimicrobial susceptibility testing
2.3.1. Disc diffusion method
This experiment was performed by the method of Hayes
and Markovic (2002) with some modifications. Propionibacterium
acnes was incubated in brain heart infusion medium
(BHI) with 1% glucose for 72 h under anaerobic conditions
and adjusted to yield approximately 1.0×108 CFU/ml.
Aliquots of molten BHI with glucose agar were used as an
agar base. A prepared inoculum was added to molten agar,
mixed and poured over the surface of the agar base and left to
solidity. A sterile paper disc was impregnated with test material
and the disc was placed on the agar. Plates were then
incubated at 37 C for 72 h under anaerobic conditions.
Staphylococcus epidermidis was incubated in tryptic soy
broth (TSB) for 24 h at 37 C and adjusted to yield approximately
1.0×108 CFU/ml. The procedures were the same as
mentioned above except the plates were incubated at 37 C
for 24 h under aerobic conditions. All disc diffusion tests were
performed in three separate experiments and the antibacterial
activitywas expressed as the mean of inhibition diameters
(mm).