Prevalence of pathogenic E. coli in diarrhoeic cattle calves and antibiotic resistance genes

الملخص EN

A total of 190 fecal samples were collected from diarrheic cattle calves aged from 1-6 months from different private farms in Kalubia and Sharkia governorates, Egypt during the period from November 2019 to September 2020.

samples were carried out to elucidate the prevalence of Escherichia coli (E.

coli).

serological identification of E.

coli isolates was done to detect the incriminated serogroups.

detection of Congo red binding activities hemolysis production and enterotoxin assay by infant mouse test as virulence factors.

also, antimicrobial sensitivity test by disc diffusion.

detection of blaTEM and tetA (A) antibiotic resistance genes of 10 isolated E.coli isolates represented by one isolate from each serogroup and the untypable strain was done by PCR.

the bacteriological examination revealed that the prevalence of E.

coli in diarrheic calves was 37.4%.

the serotyping of the isolated E.

coli revealed serogroups ; O55, O25, O111, O119, O126, O78, O157, O186, and O128, and other untypable 8 strains.

furthermore, the Congo red binding activity revealed that 43 E.coli isolates showed binding activity with an incidence of 60.6%.

out of 71 isolates, 56 showed hemolytic activity with a percentage of (78.9%) but enterotoxin production was found only in 26 isolates with a percentage of 36.6.

the antibiogram of the isolated strains was investigated ; the majority of E.

coli were resistant to amoxicillin, ampicillin, and tetracycline.

on other hand, all serogroups were sensitive to ciprofloxacin and cefotaxime.

polymerase chain reaction (PCR) was used to detect the antibiotic-resistant genes bla TEM and tetA (A) genes and the obtained results showed that all tested isolates contained these genes except the first serogroup O55.