A patient has a bacterial infection. A sample of the bacteria is taken to identify which antibiotic to use for this patient. The sample from the patient is spread evenly on an agar plate. Small paper disks soaked in each of four antibiotics are placed on the agar plate which is kept warm overnight. The diagram shows the results of the test. The shaded area shows where bacteria have grown. Which antibiotic is the most effective against these bacteria? [Figure 27.1]

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