الفهرس 
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Abstract
Two hundred samples including 40 raw milk, 40 fresh cream, 20 of each large and small scale yoghurt, 20 of each large and small scale ice cream and 40 Kareish cheese were collected randomly from dairy shops, supermarkets and farmers houses from different localities in Beni-Suef governorate, Egypt. The samples were obtained as sold to the public and transferred as soon as possible to the laboratory to be examined. The collected samples were subjected to sanitary and bacteriological examination.
The results can be summarized as follows:
A-Raw milk:
The mean value of the acidity percentage was 0.18±0.02 % and the mean count of E. coli was 8.0×105 ± 7× 105 cfu/ml, with an incidence of 75%.
Serological identification of isolated strains of E. coli were: Enterohaemorrhagic E. coli (EHEC): O26 (13.3%), O111:H4 (6.7%), O121(10%), Enterotoxigenic E. coli (ETEC): O125:H21(16.7%), O169(23.3%) and Enteropathogenic E. coli ( EPEC): O126:H7(20%), O158(10%).
B-Fresh cream:
The mean value of the acidity percentage was 0.21 ± 0.03 % and the mean count of E. coli was 2×106±1×106 cfu/gm, with an incidence of 62.5%.
Serological identification of isolated strains of E. coli were: Enterotoxigenic E. coli (ETEC) O6:H16 (16%) and Enteropathogenic E. coli (EPEC) O55:H7 (28%), O119:H6 (12%), O125:H6 (24%) and O146:H21(20%).
C-Yoghurt:
C.1.Large scale yoghurt:
The mean value of the acidity percentage was 0.98±0.02%, However E. coli could not be detected in any examined sample, so that the incidence of E. coli was 0%.
C.2.Small scale yoghurt:
The mean value of the acidity percentage was 0.96± 0.02% and the mean count of E. coli was 7×103±4×103 cfu/gm, with an incidence of 25%. cfu/gm .
Serological identification of isolated strains of E. coli were: Enteropathogenic E. coli (EPEC) O55:H7(60%) and Enterotoxigenic E. coli (ETEC) O125:H21(40%).
D-Ice cream:
D.1- Large scale ice cream:
The mean count of E. coli was 6×104 ±4×104 cfu/gm, with an incidence of 10%.
Serological identification of the isolated strains of E. coli was: Enteropathogenic E. coli (EPEC) O146:H21(100%)
D.2- Small scale ice cream:
The mean count of E. coli was 2×105±1.8×105 cfu/gm, with an incidence of 25%.
Serological identification of the isolated strains of E. coli were: Enterohaemorrhagic E. coli (EHEC) O18 (60%), Enterotoxigenic E. coli (ETEC) O159 (40%)
E-Kareish cheese:
The mean value of the acidity percentage was 1.77±0.04%, but the mean value of salt percentage was 2.98 ± 0.23% and the mean count of E. coli was 6×107±2×107 cfu/gm, with an incidence of 80%.
Serological identification of isolated strains of E. coli were: Enterohaemorrhagic E. coli (EHEC) O18 (25%), Enteropathogenic E. coli (EPEC) O55:H7(21.8%), O114:H21(9.4%), O158 (18.8%) and Enterotoxigenic E. coli (ETEC) O125:H21(9.4%) and O153:H45(15.6%).
•Genotypic characterization of E. coli:
In this study, by using the polymerase chain reaction (PCR) on some isolates of E. coli, the results revealed that all isolates harbour wzy gene.
The wzy gene encodes the O-antigen polymerase (Wzy), which plays an important role in the synthesis of the lipopolysaccharide (LPS) of E. coli. LPS are essential in processes critical for bacterial pathogenicity and environmental adaptations (Zuo et al., 2019). In addition, the expression of a functional wzy gene in E. coli strain Nissle 1917increases its ability to withstand the antibacterial defense mechanism of the blood serum (Grozdanov et al., 2002), briefly wzy gene increases the virulence and the pathogenesity of E. coli and consequently, E. coli can easily cause diseases for man representing health hazard for human health.