Multiple antibiotic resistance of Escherichia coli isolates from newborn diarrhetic calves and their virulence factors

Diarrhea in calves is a major worldwide problem threat calves industry and caused by bacterial ,viral or parasitic pathogens resulted in great economic losses. Escherichia coli is one of the major causes of calves diarrhea. This study has looked into the prevalence of E. coli, its virulence factors, antibiotic resistance genes, and antibiotic resistance pattern. Aseptically, 60 fecal samples were collected from calves that had diarrhea at the Kafr El-Sheikh Governorate, Egypt. The incidence of E.coli  were 42%. Eight (O) serogroups were identified by serogrouping of the isolated strains of E. coli: O26 (11 strains), O128 (9 strains), O111 (7 strains), O17 (4 strains), O84, O91, O55 (3 strains, each), and O159 (2 strains). The E. coli isolates' antimicrobial susceptibility to ten antimicrobial agents were tested and revealed that they were 76.19% sensitive to Gentamicin and 50% sensitive to Ciprofloxacin, but they were 100% resistant to Amoxicillin and Cefotaxim, Sulfamethoxazole-trimethoprim and Tetracyclin (92.85%,each), then Florfenicol and Amikacin (71.42%,each). Besides, multidrug resistance was determined in 92.85% of E.coli isolates. Eight E.coli serogroups were found to have the virulence genes stx1, stx2, sta and eaeA : O128 and O55 carried stx1, O26, O17and O84 carried stx2, 1 strain of each O26, O17, and O159 carried sta while all 7 serogroups except O128 showed positive result for eaeA gene. Furthermore, the antibiotic resistance genes; bla_TEM,TetA(A), sul1 and floR were present in all E.coli serogroups. In conclusion, Both shiga toxin-producing E. coli (STEC) and enterotoxigenic E. coli (ETEC) are commonly the cause of diarrhea in calves. Moreover, E.coli isolates has a multidrug resistance appearance.