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الدور الوقائي لبكتريا البفديس ضد خمج الفئران ببكتريا الاشيريكيا القولونية المنتجة لذيفان الشيكا == The Protective Role of Probiotic Bifidobacterium Against Mice Infection With Shiga Toxin Producing E.Coli O157 : H7
Author name:
سمر مصطفى محمد
Supervisor name:
شادان عباس الوانداوي
General topic:
Biology
Specific topic:
Microbiology
Degree:
Master
University:
University of Baghdad
Language:
English
University location:
Baghdad
First pages:
24T2762 - p.pdf
Abstract:
Six Bifidobacterum isolates were isolated from fully breast - fed healthy infant faeces on reduced de Man Rogosa and sharp medium (MRS - C). Isolates identified on the basis of, colonial and microscopical properties, biochemical tests, and fructose - 6 - phosphate phosphoketolase enzyme (F6PPK) activity assay in cellular extracts. Carbohydrates fermentation profile used for identification of isolates to species level. All bacterial isolates diagnosed as Bifidobacterium genus where in this study B. adolescntis was the predominant species (50%), (B4, B5 and B6), followed by B. breve (B3), B. longum (B1) and B. dentium (B2) each one represent 16.67%.Bifidobacterium isolates were screened for their antagonistic effects against test organism, clinical isolate of shiga toxin producing E.coli O157 : H7 (STEC), using agar - well diffusion method. The isolates B3 and B6 showed clear inhibitory actions, 22 mm and 15 mm diameter of inhibitions zones, respectively. The rest of the tested isolates did not pronounce any inhibitory activity.B. breve in vivo antagonistic behavior and the possible protective effects against STEC was evaluated, using streptomycin treated murine model. Murine intestines was stably colonized orally with B. breve for 14 days, in conjunction mice were challenged orally with STEC, 103 CFU / mouse / day on day 8 of experiment. Bacterteriological analysis of mice faeces at time intervals, was indicated high levels of bacterial colonization were achieved in intestine by B. breve and STEC.Colonization of mice intestine by B. Breve did not inhibited STEC cells from proliferation during infection phase. Hence, the excretion level of STEC in faeces reached to 2.4 x 10 6 CFU/ g of faeces.STEC infected mice showed no severe clinical signs, characterized by hairloss, lethargy, paralysis of fore limbs, and shed of loose faeces. In the B. breve - colonized group, the mentioned clinical signs were almost completely inhibited, except the lethargic of some animals.Immunological studies showed an increase in the levels of sIgA by 2.7 - fold from that of blood IgA in B. breve - colonized mice while, reversed values were recorded in mice infected with STEC, blood IgA level was 1.95 - fold higher than that of sIgA.Histological changes in spleen, liver, kidney, and intestine tissues of mice were studied. The histological sections clarified the protective roles of B.breve, where no effective histological disorders were appeared in B.breve and STEC - colonized mice. In the STEC - infected mice, the pathological abnormalities within the kidney was the predominant, diagnozed as ulcers in the lining membranes, glomerular and tubular epithelium necrosis, without evidence of glomerular thrombi, mild damages was appeared in liver and spleen, and characteristic attaching and effacing (A / E) lesions appeared in the large intestine sections
