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6. Procedure of antimicrobial testing
A. Inoculation of the MH plate
• Dip a sterile swab into the inoculum tube.
• Rotate the swab against the side of the tube (above the fluid level) using firm pressure,
to remove excess fluid. The swabshould not be dripping wet.
• Inoculate the dried surface of a MH agar plate by streaking the swab three times over
the entire agar surface, rotate the plate approximately 60 degrees each time to ensure an
even distribution of the inoculum
• Leaving the lid slightly ajar, allow the plate to sit at room temperature at least 3 to 5
minutes, but no more than 15 minutes, for the surface of the agar plate to dry before
proceeding to the next step
B. Placement of the sterile paper disks
• The test tube must be vortexed before use to obtain a homogeneous solution
• Using sterile forceps or disk dispenser, impregnates slightly the disk in the test tube,
place it on the surface of the inoculated and dried plate. Immediately press it down
lightly with the instrument to ensure complete contact between the disk and the agar
surface
• Once all disks are in place, replace the lid, invert the plates, and place them in a 35°C
air incubator for 24h.
After 24-48 hours of incubation, the results will be measured using a capillary ruler to determine
the diameter of the inhibition zone.