Incidence of Motile Aeromonads From United States West Coast Shellfish Growing Estuaries

The distribution of motile Aeromonas species in marine and tributary waters, sediment, and shellfish from 12 major estuarine areas in Washington, Oregon, and California with commercial or sport shellfish harvest was determined during the summer months. Aeromonas spp. were found in half of the total of 400 samples analyzed. Two enrichment broths, tryptic soy ampicillin broth (TSBA) and alkaline peptone water (APW), were compared for recovery of Aeromonas from Washington and Oregon samples. More Aeromonas were isolated using TSBA. For Washington and Oregon samples, recoveries using TSBA were 82 and 77% respectively compared to 31 and 50% using APW. For California samples, only APW was used with 28% samples positive. Of 767 isolates tested, 93.5% were positive for hemolysis, a trait reported to correlate with enterotoxin production and pathogenicity. Of the hemolysis positive strains, 59.5% were toxic to Y-1 adrenal cells.