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Study of the Pathogenicity of Aeromonas hydrophila for Man.

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Final rept. 1 Feb 83-30 Nov 85,

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Five Aeromonas hydrophila strains were selected for study from among more than 50 candidate strains collected from Thailand, Western Australia, Canada, and the United States. They were selected for the study because of possession of well characterized virulence properties or because they were clearly implicated in cases of human diarrheal illness. All were felt to be pathogenic by laboratory assays. The strains were tested biochemically and toxin production and hemagglutination patterns were characterized. Each strain was then fed to groups of 3 or 4 adult volunteers. The strains were shed by the volunteers only sporadically and except for two volunteers transcently passing unformed stools, a sustained illness did not develop. This study failed to show a relationship between virulence properties as we now understand them and pathogenicity of Aeromonas for human subjects. In studies looking at the etiology of diarrhea among groups of U.S. adult students in Mexico we found that non-EPEC serotypes of enteroadherent E. coli EAEC were isolated from 12 of diarrhea cases overall and from 30 of the patients from whom no other agents were identified. Six of 13 students from whom paired sera were collected showed a fourfold or greater rise in antibodies in serum. Two stains of EAEC were selected for study in volunteers. In doses of 7 x 10 to the 8th power and 1 x l0 to the 10th power viable cells, strain JM 221 produced a diarrheal illness in 5 of 16 subjects while 1 to 8 fed strain 189 developed a diarrheal illness. The test strains were recovered from stool throughout the study indicating intraluminal or intraintestinal replication of the test strains.

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  • Microbiology
  • Medicine and Medical Research

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