Search

Objective: We determined the distribution of serogroups and virulence factors among Escherichia coli isolates from pigs with diarrhea and/or edema disease from 10 provinces in China between 1998 and 2007., Methods: Three hundred E. coli isolates were serogrouped with O-antisera and detected for genes of enterotoxins, shiga-toxin-two-variant (Stx2e), intimin, K88, K99, 987P, F18 and F41 fimbrial antigens by PCR., Results: Among 300 isolates, 233 were determined to be placed in serogroups, 50 were unable to be serogrouped, and the rest 17 auto-agglutinated. These isolates distributed in 45 serogroups and 57.1% (133/233) belonged to 5 O serogroups: O149, O107, O139, O93 and O91. Several uncommon O serogroups were discovered. PCR analysis confirmed the genes of est I (STa), est II (STb), elt (LT), stx2e (Stx2e) and eaeA (Intimin) within the isolates. There were six pathotypes of porcine E. coli by their pathogenic factors, namely enterotoxigenic E. coli (ETEC), shiga toxin-producing E. coli (STEC), attaching-effacing E. coli (AEEC), ETEC/ STEC, AEEC/ETEC and AEEC/ETEC/STEC. The correlation between pathotypes and serogroups showed that the combinations of O149/K88/estII, O149/K88/est II+elt, O107/F18/est II, 093/est II and O98/est II were common types in ETEC strains, O139/ F18/stx2e for STEC strains, eaeA gene for AEEC strains, O107/F18/estI+stx2e, O107/F18/estII + stx2e and O116/F18/est I +elt+stx2e for ETEC/STEC strains, 091/est I/eaeA and O107/est I /eaeA for AEEC/ETEC/STEC strains"., Conclusion: ETEC was commonly associated with swine colibacillosis, whereas the kinds of enteric E. coli pathogens become more complex in China.

We constructed avian pathogenic Escherichia coli (APEC) specific DNA microarray to analyze the transcriptomes of APEC highly pathogenic strain E058 and low pathogenic strain E526 (both belonging to O2 serotype). For cultures in Luria-Bertani (LB) broth medium, 16 distinctly expressed genes were observed in strain E526, and all of them were down-regulated. For cultures in the serum of chickens, 15 distinctly expressed genes were screened in strain E526, and all of them were also down-regulated. The results suggest that DNA microarray could be used to screen distinctly expressed genes among virulence- and potential virulence-associated genes of APEC. The expression of 11 common virulence- or potential virulence-associated genes were down-regulated for strain E526 compared to those of strain E058 cultured both in LB broth and chicken serum. Meanwhile, 4 potential virulence-associated genes, aes-3, aes-10, aes-13 and aes-15 were down-regulated for strain E526 but not for strain E058, when they grew in the chicken serum. Besides known virulence factors, we observed 10 new potential virulence-related genes including aes-1, aes-2, aes-3, aes-4, aes-6, aes-8, aes-10, aes-13, aes-15 and aes-31.