Isolation Methods of Escherichia albertii from Food and Environment Water, and the Analysis of Isolate

Abstract

Escherichia albertii is an emerging enteropathogen and its distribution in various foods and environmental samples has been reported in many regions around the world. In this study, we aimed to identify effective isolation and detection methods for E. albertii in various foods and environmental water samples. E. albertii-specific polymerase chain reaction (PCR) was positive in chicken, oyster, river water, and wastewater samples, and E. albertii was isolated from these PCR-positive samples except the wastewater sample. E. albertii was not isolated from any of the samples without screening PCR; therefore, PCR is useful for the detection and isolation of E. albertii in foods and environmental water samples. The effect of two-step enrichment with four kinds of selective enrichment broth was compared with cycle threshold (Ct) values of the E. albertii-specific real-time PCR assay and the isolation results. The Ct values in three out of five samples were lower in the second enriched culture than those of the first enriched culture, and E. albertii was isolated from enriched cultures showed Ct values <25. These results suggest that the population of E. albertii in these three samples increased in the second enriched culture compared with the first enriched culture, and isolating E. albertii from an enriched culture showing Ct values <25 is an efficient method. Genetic analysis was performed to E. albertii isolates from food, environmental water, and human fecal samples, and all the isolates possessed eae, and isolates from chicken, pork, and river water samples showed the same EAOg type as E. albertii isolated from human fecal samples. Therefore, it was suggested that a continuous attention should be paid to E. albertii in food and environment.