Research Article PrevalenceandGeneticRelationshipofPredominant Escherichia coli Serotypes Isolated from Poultry, Wild Animals, and Environment in the Mekong Delta, Vietnam Lam Thanh Nguyen , 1 Nguyen Khanh Thuan , 1 Nguyen Thu Tam, 1 Chau Thi Huyen Trang, 1 Nguyen Phuc Khanh, 1 Tran Ngoc Bich, 1 Takahide Taniguchi, 2 Hideki Hayashidani , 2 andLyThiLienKhai 1 1 Department of Veterinary Medicine, College of Agriculture, Can o University, Campus II, 3/2 Street, Ninh Kieu District, Can o, Vietnam 2 Division of Animal Life Science, Institute of Agriculture, Tokyo University of Agriculture and Technology, 3–5–8 Saiwai-Cho, Fuchu-Shi, Tokyo 183-8509, Japan Correspondence should be addressed to Lam anh Nguyen; ntlam@ctu.edu.vn and Ly i Lien Khai; ltlkhai@ctu.edu.vn Received 13 September 2021; Accepted 13 October 2021; Published 11 November 2021 Academic Editor: Juan G. Chediack Copyright © 2021 Lam anh Nguyen et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Avian pathogenic Escherichia coli (APEC) is the main causative agent of avian colibacillosis, which is an important systemic disease of profound economic and clinical consequences for the poultry industry worldwide. In this study, 975 E. coli strains were isolated from 2,169 samples collected from cloacal swabs of chickens, in-farm wild animals (ants, geckos, flies, and rats), and environment. e highest proportion of E. coli isolation was obtained from chicken cloacal swabs with 71.05% (95% confidence interval (CI) 66.69–75.05%) followed by the proportions of 38.15% (95% CI 35.41–40.97%) and 38.11% (95% CI 34.15–42.24%) from wild animals or environment, respectively. Distribution of O-antigen serotypes of the E. coli isolates, including O1, O2, O18, and O78, was determined by PCR. e most pre- dominant serotype was O18 (10.56%) followed by O2 (9.44%), O1 (7.79%), and O78 (6.56%). Of note, serotype O18 was more likely distributed in the examined wild animals, especially in geckos. Polymorphic DNA fingerprints, generated by ERIC-PCR, of representative E. coli strains of each serotype revealed genetic heterogeneity of the examined E. coli, andO18 was more divergent with 63 clusters formed from 66 isolates. Furthermore, several E. coli strains from different sample sources shared high DNA fingerprint relatedness, suggesting that there exists complex transmission of E. coli from chickens to wild animals and environment and vice versa in poultry husbandry settings. Although pathotypes of the examined E. coli were not determined in this study, our results provided important findings of epidemiological and genetic characteristics of E. coli in the Mekong Delta and highlighted the prerequisite of stricter biocontainment to reduce the prevalence and consequences of APEC in poultry production. 1.Introduction Escherichia coli (E. coli) is a ubiquitous organism in the gastrointestinal microbiota of human and animals. A ma- jority of E. coli are nonpathogenic and play an important role in host metabolism, immunology, and nutrition [1]. How- ever, several E. coli strains can acquire specific virulence factors and become pathogenic E. coli that are capable of causing a wide range of diseases in human and animals [2]. Concerning animal health, avian pathogenic E. coli (APEC) is the primary cause of avian colibacillosis; the disease is characterized by multiple systemic syndromes such as col- isepticemia, airsacculitis, perihepatitis, pericarditis, swollen- head syndrome, and fatal hemorrhagic septicemia, resulting in high morbidity, mortality, and carcass condemnation [2]. us, APEC is responsible for severe economic and clinical Hindawi Veterinary Medicine International Volume 2021, Article ID 6504648, 12 pages https://doi.org/10.1155/2021/6504648