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Study on the pathogenicity of Campylobacter jejuni by modifying the medium
1Department of Microbiology, University of Dhaka, Bangladesh.
Abstract:
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.
Insights
Iron supplementation enhanced Campylobacter jejuni growth. Pathogenic strains showed cytotoxicity on HeLa cells, suggesting sonicated extracts can differentiate toxigenic C. jejuni.
Area of Science:
- Microbiology
- Pathogen Research
Background:
- Campylobacter jejuni is a leading cause of global diarrheal illness.
- Current methods for identifying toxigenic C. jejuni strains are insufficient.
- Pathogenicity studies require reliable methods for strain differentiation.
Purpose of the Study:
- To investigate the effect of iron (FeCl3) on C. jejuni growth and pathogenicity.
- To evaluate the utility of modified media and cell-based assays for identifying pathogenic C. jejuni.
- To determine if sonicated extracts can distinguish toxigenic C. jejuni strains.
Main Methods:
- Modified standard C. jejuni medium with varying FeCl3 concentrations.
- Pathogenicity assays using rabbit ileal loop, Chinese hamster ovary (CHO), human epithelial cervical carcinoma (HeLa), Y-1 adrenal cell lines, and suckling mice.
- Assays with sonicated extracts and cell-free culture supernatants.
Main Results:
- Increased FeCl3 concentrations enhanced C. jejuni growth.
- Only five isolates exhibited cytotoxicity on HeLa cells; other cell lines were unaffected.
- Rabbit ileal loop assays showed hemorrhage, not fluid accumulation; no heat-stable toxin detected.
- Sonicated extracts demonstrated a greater effect on HeLa cells than culture supernatants.
Conclusions:
- FeCl3 supplementation promotes C. jejuni growth.
- HeLa cell monolayer assays, particularly with sonicated extracts, show potential for differentiating pathogenic C. jejuni strains.
- Further research is needed to confirm the efficacy of this method for clinical diagnostics.