Effect of irradiation on prevalence of E.coli O157: H7 in raw milk and some milk products [with 6 tables]

A total of one hundred and thirty random milk and some milk products samples were collected from different markets, and were examined for the presence of Escherichia coli O157:H7. The organism could be isolated from one sample [2%] of each of milk and cheese samples, but it failed to detect in yoghurt samples. An important cause of haemolytic anaemia syndrome and lethal effect on mice was detected, while enterotoxin of strain gave maximum secretion in rabbit ligated ileal loop Raw milk and milk products samples [cheese and yoghourt] free from E. coli O157:H7 were inoculated by strain of E. coli O157:H7 obtained from a Bacteriology Veterinary Lab. The effects of irradiation on the inoculated milk and milk products stored at 8°C -and 5°C were determined. As survivor level of E. coli O157:H7 following gamma irradiation appeared completely discarded in refrigerator on 1, 2 and 3 days of incubation at 5°C. The cytotoxin production was completely stopped by irradiation at 0.25-0.53 kgy

Characterization of campylobacter isolates from sheep with particular reference to enterotoxin production

C. jejuni subsp. jejuni, C. coli and C. laridis were isolated from apparently normal and diarrhoeic sheep with an incidence of 10% and 20%, respectively. C jejuni subsp. jejuni was the most predominant species with an overall incidence of 10.7%. All Campylobacter strains isolated from diarrhoeic animals were invasive to Hela cells and their cytotoxin produce degree [++] and [+++] of changes in Vero cells and titer of toxins were high [64-128]. C jejuni enterotoxin isolated from diarrhoeic sheep gave maximum secretion in rat ligated ileal loops. While enterotoxin of other strains evoked less fluid secretion in rat ligated ileal loops. SDS PAGE of heat labile enterotoxin extracted from isolated strains indicated protein profiles ranging from 49.3 to 59.3 KD. In immunized-challenged rats the fluid secretion was reduced by 70 to 80% less than the value for similar challenged unimmunized control rats. Antibody titers measured by ELISA showed four folds higher level than that in control animals

Immunological studies on pasteurella haemolytica in sheep

In the period from January-July 2001 respiratory manifestations appeared on 53 out of 239 sheep at Sakha station of reproduction Research center, causing death of 30 cases. Clinically history symptoms and necropsy findings were reported. Pasteurella haemolytica was incriminated as the causative agent of this problem. This organism was isolated from nasal swabs of clinically diseased sheep and from pharyngonasal swabs, lung tissue of six emergency slaughtered cases. The isolates were identified biochemically and serologically and using pathogenicity test. Two antigens leukotoxin and whole cell associated with Pasteurella haemolytica. SDS-PAGE of leukotoxin yield four protein bands ranged from 80 KDa to 98 Kda while whole cell antigen yielded 10 protein bands ranged between 22 to 85 KDa. Antigens associated with P. haemolytica whole cell and leukotoxin were identified for their immunogenic activity by neutralization test and ELISA. The neutralizing antibodies against leukotoxin in sheep were significantly higher than antibodies against the whole cell antigen. Also, antibodies titre to leukotoxin by ELISA were significantly higher than antibody titre to whole cell antigen, Pathological examination revealed that the sacrified sheep suffered from pneumonia with various lesions in lymph nodes, liver, kidney, heart and brain