Pathogenic amoebae in ocean sediments near wastewater sludge disposal sites [Maryland]

Small free-living amoebae belonging to the family Acanthamoebidae were cultured from 17.5% (40/229) of the seabottom sediments sampled at or near the Philadelphia-Camden wastewater sludge disposal site. Stations that yielded the amoebae were distributed for approximately 37 to 40 km to the northeast and southwest of the dumpsite and for approximately 10 km to the east and west. Amoebae were formed at only 2% of the control stations. Bacterial most probable numbers (MPNs) obtained from the same sediment samples used for amoeba isolations showed that both groups of organisms followed an identical spatial distribution pattern. Two amoeba species, Acanthamoeba culbertsoni and A. hatchetti, killed laboratory mice, whereas four others did not-A. polyphaga, A. castellanii, A. rhysodes, and A. triangularis. One unidentified species, possibly new, was not tested in mice.