Mueller-Hinton Agar (MHA) is the standard medium for antimicrobial disk diffusion susceptibility testing of rapidly growing aerobic bacteria but cannot support fastidious organisms like S. pneumoniae. For S. pneumoniae, Mueller-Hinton Blood Agar (MH BAP), which contains 5% sheep blood, is recommended. Testing is performed using 90 mm, 100 mm, or 150 mm Petri dishes based on requirements.