Ninety-one F4⁺ pathogenic Escherichia (E.) coli and 181 F18⁺ pathogenic E. coli were isolated from piglets suffering enteric colibacillosis during 2007-2016. These strains were analyzed for O-serogroups, adhesin genes (eae, paa, AIDA-1), toxin genes (LT, STa, STb, Stx2e, EAST-1), and their susceptibility to 16 antimicrobials using disc diffusion method. We found that O149 and O139 were predominant serogroups in F4⁺ E. coli (36.3%) and F18⁺ E. coli (16.6%), respectively. AIDA-1 was the most predominant adhesin gene in F18⁺ E. coli (26.5%) while paa was the most predominant adhesin gene in F4⁺ E. coli (30.8%). LT (70.3%), STb (84.6%), and EAST-1 (73.6%) were detected with high frequency in F4⁺ E. coli. However, STa (43.6%) and Stx2e (49.2%) were the predominant toxin genes detected in F18⁺ E. coli. Both F4⁺ and F18⁺ E. coli showed high resistance to tetracycline (F4⁺: 91.2%, F18⁺: 90.6%), chloramphenicol (F4⁺: 87.9%, F18⁺: 92.3%), and streptomycin (F4⁺: 89.0%, F18⁺: 84.0%).  F18⁺ E. coli showed higher resistance to colistin (9.4%) rather than F4⁺ E. coli (2.2%). In summary, we compared serogroups, virulence factors, and antimicrobial susceptibility of F4⁺ and F18⁺ E. coli from diarrheic weaned piglets. Results of this study could be used to design control measures for enteric colibacillosis in piggeries.

To Cite This Article: Do KH, Byun JW and Lee WK, 2019. Serogroups, virulence genes and antimicrobial resistance of F4⁺ and F18⁺ Escherichia coli isolated from weaned piglets. Pak Vet J, 39(2): 266-270. http://dx.doi.org/10.29261/pakvetj/2019.021