Imagine that you have set up a Kirby Bauer experiment on Mueller Hinton agar (non-selective agar) in order to test if Escherichia coli is susceptible or resistant to Drug X. After 24 hours, you notice a zone of inhibition (clear zone) around your antibiotic disc and determine that E. coli is susceptible to Drug X. You then take a cotton swab and subculture a sample from this zone of inhibition (where no growth was apparent) onto a new agar plate without antibiotics and after 24 hours you see growth of E. coli. What can you conclude about Drug X? Explain your answer for full credit.