Peptone Beef Extract Glycogen Agar, a Selective and Differential Aeromonas Medium

Studies directed toward the formulation of a selective/differential pour plate medium for Aeromonas species resulted in the following composition (in grams per liter): Bacto-peptone, 10; Bacto-beef extract, 10; glycogen, 4; NaCl, 5; sodium lauryl sulfate, 0.1; bromthymol blue, 0.1; agar, 15. The pH of the medium after autoclaving was 6.9–7.1. After the agar had gelled and the surface had dried, plates were overlaid with 2% nonnutrient agar in distilled water.Aeromonas colonies were recognized by their characteristic size and yellow color in this medium. It has been used to monitor the concentrations of A. hydrophila and A. salmonicida in hatchery waters, to recover these organisms from the intestines and lesions of experimentally infected fish, to isolate A. hydrophila from fish mucus and pet turtles, and to determine aeromonad survival times in water.