Assessing Virulence Factor Genes in Pig-Derived Escherichia coli from the Region of Vojvodina Treated with Postbiotic Substance and Herbal Essential Oils

Altogether 16 pigs-derived Escherichia coli (isolated pig farms in Vojvodina region, Serbia) were taxonomically identified using MALDI-TOF mass spectrometry; 14 (87.5%) with secure genus identification/probable species identification and two with highly probable genus identification. Testing virulence factor genes, the gene fimA was detected in 62.5% of strains. Crl gene was detected in 14 strains (87.5 %). Ec3419/2 contained 5 analyzed genes. Using Congo red agar, five E. coli were biofilm-forming which was not confirmed using the quantitative plate assay. The strains were mostly multiresistnt to antibiotics. Each E. coli was found with production of non-useful enzymes in values from 5 up to 30 nmol. However, they were susceptible to herbal essential oils (HEO-oregano, thyme, sage, and coriander) with average inhibitory zone from 15 up to 27 mm in diameter. Tey were also (6) susceptible to postbiotic substance (Ent) 412 (activity up to 6400 AU/ml. Postbiotic substances represent one of novel approaches to fight with virulence factor possessing E. coli. Moreover, their combination with HEO increases their antimicrobial effect. These treatment conditions correspond with One Health Concept.