Accumulation and elimination of Escherichia coli and Salmonella typhimurium by hard clams in an in vitro system.

A simple, in vitro protocol was devised to study contamination by and subsequent elimination of Escherichia coli and Salmonella typhimurium in the hard clam, Mercenaria mercenaria. The test bacteria were eliminated rapidly at similar rates for 8 h after exposure and less rapidly thereafter. At 24 h, numbers of E. coli had declined more than S. typhimurium. Bacteria were cleared in the form of rapidly sedimenting fecal and pseudofecal particulates with which the bacteria were stably associated. Ionic bonding was apparently not involved in this association. Degradation of substantial numbers of bacteria occurred in feces at between 6 and 24 h.