ABSTRACT
Studying comprehensively the pathogenesis of local isolate of C. jejuni in our country with their details by using ultrastructural studies depending on suitable protocol and animal model. Newly local isolate of C. jejuni [CJM6] which isolated from children was used to study the pathogenesis of such bacteria after oral administration of 1.7x10 viable cell /ml for gnotobiotic mice which were as animal model. Under scanning electron microscopy [SEM], the earliest colonization with huge numbers of C. jejuni appear at 24 hours post inoculation [P.I], and early adherence at 48 hours P.I with normal mucosal appearance. The mucosal and edema and loss of microvilli in some areas of epithelial surface were observed 3 and 4 days after inoculation, due to early penetration of C. jejuni. In 5 days after inoculation, the mucosa revealed irregular opening of cecal crypts with reduction of goblet cells numbers as well as destroyed cecal mucosa. While 6 and 7 days P.I revealed patchy erosion and necrosis with persistence adherence and colonization. Under transmission electron microscopy [TEM] the colonization was seen within the mucous environment of cecal epithelium, with normal appearance of cellular details. 3 and 4 days P.I some cases showed mixed healthy cells and other showed abnormalities of microvilli, as well as presence of free invasive C. jejuni, within epithelial cytoplasm, while deeper crypts were seen to be heavily colonized. Degenerative changes included partial loss of surface mucosal microvilli with numerous invasive C. jejuni mucosal goblet cells, while others seen within membrane vacuole in cytoplasmic epithelial cells 5 days P.I. At later stage of infection degenerative changes of microvilli ranged from elongation, fusion swelling, budding to abnormal shortening and microvillous-cytoplasmic extrusion toward C. jejuni within cecal lumen as well as exfoliated microvilli and apical cytoplasm into lumen. Gnotobiotic mice improved to be suitable model for studying pathogenesis by producing transient bacteremia, diarrhea and intestinal lesions resembling that which may occur in human. EM [SEM and TEM] is an important in increasing our understanding of disease pathogenesis which include colonization, adherence, penetration, multiplication and invasion as well as producing several pathological changes