Imagine you found S. aureus to be resistant to Penicillin by Kirby Bauer analysis, but susceptible to Penicillin treatment in liquid culture (in other words, a MIC was determined). Which of the following are possible explanations for this inconsistency? a. The concentration of Penicillin was higher in the Penicillin antibiotic disk than that used in liquid culture treatment.
b. The Penicillin disks used for Kirby Bauer analysis were expired/no longer active.
c. The concentration of bacteria was lower on the Mueller Hinton plate for Kirby Bauer analysis than that used in liquid culture treatment