الفهرس 
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Abstract
A total of266 collected rectal swabs (141) from cattle calves and 125
from buffalo calves) were examined bacteriologically. E. coli was present
in 20 (14.2%) and 29 (23.2%) respectively.
-Bacteriological examination of266 diarrhoeic calves with different ages
from birth upto 6 months old revealed that E. coli infection was increased
during the first few weeks of life and decreased by aging.
-All 49 E. coli isolates were tested serologically. E. coli 0157 was
present in 2 isolates in an incidance of 4.0%.
-Studying the virulence factors of E. coli revealed that:
-10.2 (5/49) were a - Hly producing E. coli.
-4.0 % (2/49) were E-Hly producing E. coli, 1 of the two was serotyped
E. coli 0157.
-Using peR to detect the presence of STa gene in three groups ofE. coli
revealed that 100.0% (2/2) E. coli 0157 group were negative, 16.6%
(116) of the haemolytic group was positive and 66.6% (4/6) of random E.
coli group were positive. -Two E. coli isolates were positive by 0157 antisera and shared CPE in
Vero cells indicating Verotoxigenic E. coli 0157 (0157 VTEC).
-Two E. coli isolates were negative by 0157 antisera and shared CPE in
Vero cells indicating Verotoxigenic non-0157 (Non-0157 VTEC).
-One E. coli 0157 was positive for tube agglutination test indicating E.
coli 0157: H7.
-All of the E-Hly producing isolates were Verotoxin producing E. coli.