Isolation and Characterization of Pathogenic E. coli

E. coli strain PCN033 was isolated from the brain of a diseased pig from Hunan Province, China [10 (link)]. E. coli strain PCN061 was isolated from the lung of a diseased pig from Hunan Province, China. These two strains were routinely cultured in Luria–Bertani (LB) medium at 37 °C. According to Johnson et al. [12 (link)] and Ding et al. [11 (link)], ExPECs were defined as E. coli isolates containing two or more virulence markers: papA/papC, sfa/foc, afa/dra, kpsMTII and iutA. PCN033 and PCN061 were examined in PCR for the presence of the above virulence markers. Serotyping, phylogenetic grouping and virulence analysis in mice model of these two strains were performed in previous study [9 (link)]. The serotypes of these strains were identified by serum agglutination assay using specific O-antigen antiserum in the China Institute of Veterinary Drugs Control, Beijing, China. The phylogenetic groups of PCN033 and PCN061 strains were determined based on PCR detection of the chuA and yjaA genes and DNA fragment TSPE4.C2 [83 (link)].