التاثيرات المرضية للذيفان الخلوي المستخلص من بكتريا Campylobacter jejuni المعزولة محليا == Pathological Effects of the Cytotoxin Extracted from a Locally Isolated Campylobacter jejuni
Author name:
سيناء محمد علي السباهي
Supervisor name:
ضحى سعد صالح
General topic:
Biology
Specific topic:
Microbiology - Bacteria
Degree:
Doctorate
University:
University of Baghdad
Language:
English
University location:
Baghdad
First pages:
24T3075 - p.pdf
Abstract:
This study was done to investigate the presence of Campylobacter jejuni in bloody diarrheal stool collected from hospitalized children with gastroenteritis. Campylobacter was isolated from only 4 specimens of a total number of 186; upon identification three isolates were identified as C. jejuni while the fourth isolate was found to be C. coli.Isolation of campylobacters was done using a locally prepared modified, blood - free, charcoal selective medium. It was the first time in which such medium was used for cultivating Campylobacter locally. The efficacy of this medium was very clear in comparison with the ordinarily used blood containing medium for inhibiting almost all fecal flora.Biochemical and physiological tests were used to identify and differentiate C. jejuni from the other Campylobacter species. The antibiotic sensitivity test showed that all isolates were sensitive to erythromycin, chloramphenicol, amikacin and ciprofloxacin, while resistance was found for cephalothin, ceftriaxone cefotaxime, ampicillin and trimethoprim.Tissue culture technique was used to determine C. jejuni of high cytotoxin productivity using continuous cell lines (HeLa and Vero cell lines); this isolate was used for further investigations in the study.In this study, the cytotoxin of the highest cytotoxin producing C. jejuni isolate was extracted locally for the first time and purified, using gel filtration chromatography with Sephadex G100.The purified cytotoxin revealed a single band which was observed by polyacrylamide gel electrophoresis (PAGE) under the denaturing conditions. The molecular weight of the purified cytotoxin was approximately equal to 43 KDa as determined by PAGE.Using newly hatched chicks (as an animal model),the ID50 value was 3.71x10 4 cfu /ml. The ID50 decreased from 3.71x10 4 to 1.66 x 10 3 cfu/ml when 50 μg of cytotoxin was mixed with the bacterial suspension, this result reflects the role of cytotoxin on the pathogenesis of C. jejuni infection.In the present study, oral inoculation of newly hatched chicks with the C. jejuni isolate resulted in clinical and histopathological damages leading to bloody diarrhea similar to that observed in humans infected with C. jejuni.The post - mortal examination of chicks' viscera showed an accumulation of fluid in chick intestines which were distended with watery fluid; also there was obvious hepatomegaly with yellow spots, and swelling of the gall bladder. The associated infection with the C. jejuni cells and their cytotoxin induced more progressive tissue damage represented by a more severe intestinal distension and congestion.The histopathological examination of the small and large intestine of chicks infected with Campylobacter cells, showed mucosal sloughing, congestion of blood vessels, infiltration of inflammatory cells in the mucosal and submucosal layers, and accumulation of edematous fluid in the mucosal layer. The examination of chicks infected with Campylobacter cells and the cytotoxin revealed the presence of the same lesion, but more severely with the presence of hemorrhage in the lumen. These results could be important evidence of the role of cytotoxin as a virulence factor on the pathogenicity of C. jejuni
