Pathogenicity of aeromonas Sp for balb/c mice

Clinical strains of Aeromonas hydrophia and Aeromonas sobria were used to develop a mouse model for determining virulence potentials of food isolates. Intraperitoneal injection with these strains caused hemorrhaging and death of 10-12 week old male BALB/c mice within 24 h post challenge. Nonsupplemented injections of Aeromonas sp. suspensions resulted in a median LID 50 value of 4.9 X 107 cells, whereas supplementation with 0.1 ml of 5% iron dextran with the bacterium decreased the LID 50 value to 3.1 X 10 7cells. Immunosuppression of the mice with cadmium chloride did not substantially alter the lethality for mice. Boiled suspensions 109 cells did not cause more deaths, indicating a lack of pathological contribution by the LPS component when using this approach for virulence assessment. Isolates of Aeromonas sp. from retail chicken, beef and pork products were supplemented with iron dextran and injected into BALB/c male mice. Twenty-two of 26 mice injected with 26 A. hydrophila food isolates died; 13 of 14 mice injected with A. sobria isolates died; and 10 of 16 mice injected with A, caviae isolates died. These results indicate that approximately 80% of foodborne aeromonas are lethal for mice via intraperitoneal challenge. This virulence assay may or may not be an appropriate choice to assess the potentials of foodborne isolates of Aeromonas sp. to cause disease in humans

Potential pathogenic mechanisms of animal-passed virulence-enhanced strains of campylobacter jejuni/coli

In order to study the potential pathogenic mechanisms, live cultures, culture-filterates and Poly-myxin B released extracts from original and animal-passed strains of C jejuni/coli were compared by a neonatal mouse infection and in-vitro Vero-Cell cytotoxicity. The cell fractions from mouse-passed strains elaborated strong cytotonic and cytotoxic activity causing elongation, granular appearance and lysis of Vero-Cells. Only weak enterotoxie activity was associated with the original strains. Partial neutralization of the cytotonic activity by mono-clonal anticholera toxin [CT] suggested immunological relationship between the toxins which was also demonstrated by Ouchterlony immunodiffusion using polyclonal anti - CT serum. The in-vivo significance of CT like and other toxic materials produced by Campylobacter strains during animal-passage remains to be assessed