Comparative study of colonizing and noncolonizing Campylobacter jejuni

Area of Science:

• Microbiology
• Veterinary Science
• Gastroenterology

Background:

• Campylobacter jejuni is a leading cause of bacterial gastroenteritis.
• Congenic strains of C. jejuni, A74/O and A74/C, exhibit differential intestinal colonization in chickens.
• Understanding colonization mechanisms is crucial for controlling C. jejuni infections.

Purpose of the Study:

• To investigate the mechanisms underlying the differential colonization of chicken intestines by C. jejuni congenic strains A74/O and A74/C.
• To identify specific bacterial or host factors that promote or inhibit C. jejuni colonization.

Main Methods:

• Comparative analysis of plasmid content and DNA restriction enzyme digestion patterns.
• Transmission electron microscopy (TEM) for ultrastructural examination.
• Light and electron microscopy of chicken cecal tissue explants cultured with bacterial strains.
• Immunofluorescent and silver staining for bacterial localization.
• Chemotaxis assays using mucin and fucose.

Main Results:

• No significant differences were found in plasmid content or DNA restriction profiles between strains A74/O and A74/C.
• Both strains induced necrosis of villus epithelial cells.
• Strain A74/C was localized deep within intestinal crypts, while A74/O was found primarily with sloughed cells.
• TEM confirmed A74/C's presence in crypts, unlike A74/O.
• No differences in chemotactic responses to mucin or fucose were observed.

Conclusions:

• The ability of C. jejuni strain A74/C to colonize chicken intestines is associated with its capacity to penetrate and reside within epithelial crypts.
• Strain A74/O lacks this crypt colonization ability, contributing to its failure to colonize.
• Bacterial association with epithelial cells or chemotaxis does not appear to be the primary determinant of colonization differences.