Serotyping and Virulence Genes Detection in Escherichia coli Isolated from Fertile and Infertile Eggs, Dead-in-Shell Embryos, and Chickens with Yolk Sac Infection

Abstract

Escherichia coli is a common avian pathogen mainly associated with extraintestinal infections such as yolk sac infection (YSI). The aim of this study was to determine the serotypes and the presence of some virulence genes of E. coli strains isolated from different samples in a vertically integrated poultry operation in Mexico. Two hundred sixty-seven E. coli isolates from different samples were serotyped using rabbit serum against the 175 somatic (O) and 56 flagellar (H) antigens of the typing schema. Virulence genes were determined by colony blot hybridization, using DNA probes for st, eae, agg1, agg2, bfp, lt, cdt, slt, and ipaH diarrhea-associated virulence factors. The serogroup of 85% of the strains was determined; O19 (12%), 084 (9%), 08 (6%), and 078 (5%) were the most common. Using the complete antigenic formula (O and H), O19:NM (n = 31) was the serotype most frequently isolated from dead-in-shell embryos and in broilers that had died on the fourth, fifth, sixth, and seventh days after hatch. One hundred ten strains (41.2%) hybridized with one or more of the used probes. Of these, ipaH (72%), eae (30%), and cdt (27%) were the most common. Considering the origin of the respective isolates, 40% of the broiler farm strains were positive for at least one probe. Results show that some avian E. coli strains isolated in Mexico are included in avian pathogenic E. coli serotypes not previously reported, suggesting that they could be specific for this geographic area. The wide distribution of the ipaH gene among nonmotile strains suggests that this invasiveness trait could be important in YSI pathogenesis. On the other hand, some other genes could contribute to E. coli virulence during YSI.

Epidemiological and Bacteriological Studies on Dead-in-Shell Embryos

“…Escherichia coli constituted 48.6% of the bacteria isolated from the three hatcheries. This finding is in agreement with that reported by others working on the same topic and in the same geographic location [1,9,10]. Similarly, Escherichia coli are responsible for the largest numbers of dead embryos in the three hatcheries (7 dead embryos).…”

Virulence Genes and Antimicrobial Susceptibilities of Hemolytic and Nonhemolytic Escherichia coli Isolated from Post-Weaning Piglets in Central Thailand

“…Therefore, routine diagnosis of pathogenic field strains of E. coli on the basis of hemolysis might not provide sufficient evidence of their pathogenic potential. Many virulence factors have been identified and are mainly encoded on plasmids or on chromosomal regions that are detectable by DNA probe hybridization [5,14,30]. In the current study, over 70% of the HEC isolates tested harbored genes encoding for LTh, STp and Stx2e, indicating the existence of endemic ETEC and STEC in our study area.…”

Detection of ipaH gene in Large Plasmid of Escherichia coli Isolated from Different Sources of Bangladesh

“…The ipaH is one of the most important diarrheagenic genes that are involved in invasion and intracellular movement of colonic epithelium cells. Similar genes have also been detected in avian pathogenic E. coli as proved by colony blot hybridization 9 . Therefore, it indicates the necessity of detailed characterization of large plasmid of E. coli on the basis of its virulent ipaH genes.…”