Approximately 10% of people living in the United States are allergic to penicillin. A research team has developed a new antibiotic that could potentially replace penicillin and treat a wide variety of bacterial infections. To test their theory, the scientists grow Streptococcus pyogenes in petri dishes. S. pyogenes causes numerous infections in humans, like pharyngitis, tonsillitis, and scarlet fever. These diseases are normally treated successfully with penicillin. They expose S. pyogenes to their new strain of antibiotic to determine its effectiveness. What are good positive and negative controls?