Study on the pathogenicity of Campylobacter jejuni by modifying the medium.

Campylobacter jejuni has been documented as one of the major aetiological agents of diarrhoeal illness all over the world. Studies revealed its pathogenicity by different assay methods, but none could be strongly recommended as a tool for differentiating toxigenic strains of C. jejuni. This study was an attempt to demonstrate better its pathogenicity by media modification. Fifteen isolates of C. jejuni recovered from diarrhoeal patients at the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), Dhaka Hospital were included in this study. The standard medium for C. jejuni was modified by the incorporation of FeCl3 at different concentrations. The pathogenicity of the test isolates were studied by rabbit ileal loop assay; Chinese hamster ovary (CHO), human epithelial cervical carcinoma (HeLa); Y-1 adrenal cell lines and suckling mouse assay. Sonicated extracts of the test organisms, grown with FeCl3 supplement, were also assayed. An enhanced growth of C. jejuni was obtained with the increasing concentration of FeCl3 supplementation in the medium. Only five isolates of C. jejuni produced cytotoxic effect on HeLa cell monolayer. Other cell lines were not affected by the test specimens or sonicates. Rabbit ileal loop assay did not reveal any fluid accumulation but on dissection, the test loops were found highly haemorrhagic. No heat-stable (ST) toxin could be detected. Cell-free culture supernatant of patients' isolates of C. jejuni had an effect on HeLa cell monolayer. Sonicated extracts of patients' extracts had a greater effect on HeLa cell monolayer. Pathogenic strains of C. jejuni might be distinguished on HeLa cell monolayer using its sonicated extracts.