Comparison of selective media for primary isolation of Aeromonas species from human and animal feces.

Five selective media were evaluated for their effectiveness in the primary isolation of Aeromonas spp. from human patients with acute diarrhea and from healthy domestic animals. Sheep blood agar with 30 mg of ampicillin per liter (ASBA30) yielded a significantly higher percentage of positive specimens as compared with the four other media. The effective combination of two selective media with which 98% of all isolates were detected and with which all of the three human-associated Aeromonas spp. could be isolated was ASBA30-DNase-toluidine blue agar. ASBA30 was the most sensitive medium since it permitted more growth of Aeromonas colonies and effectively suppressed competing microflora. We recommend the use of ASBA30-DNase-toluidine blue agar for investigations in which an attempt is made to assess the significance of Aeromonas spp. in the etiology of human diarrhea.