Aeromonas hydrophila in acute diarrheal disease: detection of enterotoxin and biotyping of strains

Abstract

Eleven isolates of Aeromonas species from human stool cultures were found to produce enterotoxin activity as determined by assay of culture filtrates in rabbit intestinal loops and rabbit skin and on adrenal Y1 cells. Hemolysin(s) and a cytotoxic protein were found to interfere in all three assay systems but could be inactivated upon heating at 56 degrees C or by specific antihemolysin. Biotyping of each isolate was performed with a conventional test system and with API 50E and APIZYM kit systems (Analytab, Inc.). No single test of the more than 70 biochemical reactions investigated was found to correlate with enterotoxigenicity in the strains of Aeromonas hydrophila examined. All strains were found to belong to ideal phenotypes of A. hydrophila, but each strain possessed its own biochemical profile.