Calf diarrhea is one of the considerable infectious diseases in calves, which results in tremendous economic losses globally. To determine the prevalence of Shiga-toxigenic
E. coli (STEC) and Enterotoxigenic
E. coli (ETEC) incriminated in calf diarrhea, with special reference to Shiga- toxins genes (
stx1 and
stx2) and enterotoxins genes (
lt and
sta) that govern their pathogenesis, as well as the virulence genes;
eaeA (intimin) and
f41(fimbrial adhesion), and the screening of their antibiogram and antimicrobial resistance genes;
aadB,
sul1, and
bla-TEM, a total of 274 fecal samples were collected (April 2018–Feb 2019) from diarrheic calves at different farms in El-Sharqia Governorate, Egypt. The bacteriological examination revealed that the prevalence of
E. coli in diarrheic calves was 28.8%. The serotyping of the isolated
E. coli revealed 7 serogroups; O
26, O
128, O
111, O
125, O
45, O
119 and O
91. Furthermore, the Congo red binding test was carried out, where 89.8% of the examined strains (n = 71) were positive. The antibiogram of the isolated strains was investigated; the majority of
E. coli serotypes exhibit multidrug resistance (MDR) to four antimicrobial agents; neomycin, gentamycin, streptomycin, and amikacin. Polymerase chain reaction (PCR) was used to detect the prevalence of the virulence genes;
stx1,
stx2
lt,
sta,
f41 and
eaeA, as well as the antimicrobial resistance genes;
aadB,
sul1, and
bla-TEM. The prevalence of STEC was 20.2% (n = 16), while the prevalence of ETEC was 30.4% (n = 24). Briefly, the Shiga toxins genes;
stx1 and
stx2, are the most prevalent virulence genes associated with STEC, which are responsible for the pathogenesis of the disease and helped by the intimin gene (
eaeA). In addition, the
lt gene is the most prevalent enterotoxin gene accompanied by the ETEC strains, either alone or in combination with
sta and/or
f41 genes. The majority of pathogenic
E. coli incriminated in calf diarrhea possesses the
aadB resistance gene, followed by the
sul1 gene. Enrofloxacin, florfenicol, amoxicillin-clavulanic acid, and ampicillin-sulbactam, are the most effective antimicrobial agents against the isolated STEC and ETEC strains.
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