Fig. 2. The growth of coagulase-negative staphylococcus and diphtheroids on 5% sheep blood agar with inserts of gram-stained morphologies. The long white arrows point to the broken-line circle containing the diphtheroid colonies and the insert of gram-positive pleomorphic rods that are characteristic of diphtheroids. The short white arrows point to the larger coagulase-negative staphylococcus colony and the insert of gram-positive cocci. (Photographed by Phyllis Kaufman, University of Pittsburgh Medical Center, Pittsburgh, PA.)