Genetic diversity and antimicrobial resistance of Escherichia coli as microbial source tracking tools of Karaj River, Iran Roohollah Kheiri and Leili Akhtari ABSTRACT The aim of this study was to analyze the enterobacterial repetitive intergenic consensus (ERIC)-types, phylo-groups and antimicrobial resistance (AMR) patterns of Escherichia coli and to investigate if these approaches are suitable for microbial source tracking (MST). E. coli strains were isolated from cattle faeces and Karaj River. For genetic diversity, AMR profile, and phylo-grouping, we applied ERIC- PCR, disk diffusion, and multiplex-PCR, respectively. Fifty isolates from each sample group were used in the study. ERIC fingerprinting produced ten different bands, demonstrating 64 unique and 36 repetitive profiles. Six isolates from the river showed the same ERIC pattern of the cattle, of which four expressed the same AMR profile. E. coli isolates from water were represented in A, B1, C, and D phylo-groups. Phylo-groups A, B1, and E were more prevalent in the cattle isolates and B2 was absent in both sources. Three of the water isolates with the same ERIC-type and AMR to cattle isolates showed the same phylo-groups. Genetic characteristics, AMR, and phylo-groups of the isolates from the river are diverse and complex. For accurate MST, complementary approaches should be applied together and a comprehensive library should be provided. Roohollah Kheiri (corresponding author) Alborz Province Water and Wastewater Company, Alborz, IRI E-mail: r_kheirik@yahoo.co.uk Leili Akhtari Tehran Water and Wastewater Supply and Treatment Company, Tehran, IRI Key words | antimicrobial resistance, ERIC-PCR, Escherichia coli, microbial source tracking, phylo-groups, water INTRODUCTION Escherichia coli is a normal inhabitant of the lower intesti- nal tract of warm-blooded animals and humans, therefore the presence of E. coli in water is an implicit indicator of recent faecal contamination and the risk of enteric pathogens. Although the majority of E. coli strains are com- mensals, some are known to be pathogenic, causing intestinal and extra-intestinal diseases, such as diarrhea and urinary tract infections (Lyautey et al. ). The poss- ible reservoir of faecal contamination includes surface runoff from manure-treated agricultural land or farm animal feedlots, failing or inadequate septic systems, sewer overflow, and wildlife, along with domestic sewage disposal and animal husbandries near the bank (Kon et al. ). Water pollution raises considerable public health concern as it can transport pathogenic parasites, bacteria and viruses Borges et al. (). Hence, understanding the origin of faecal pollution is paramount in assessing associated health risks as well as the actions necessary to solve the pro- blem (Dombek et al. ). Tracing the origin of faecal pollution by using microbiological, genotypic, phenotypic, and chemical methods is termed microbial source tracking (MST). When applying MST, it is critical to introduce appli- cable methods by which the faecal contamination sources can be identified (Lu et al. ). Different approaches have been proposed for tracking the contamination sources. These approaches can be broadly divided into library-depen- dent and library-independent techniques. Antimicrobial resistance (AMR) profiling and DNA fingerprinting-based 1468 © IWA Publishing 2017 Water Science & Technology: Water Supply | 17.5 | 2017 doi: 10.2166/ws.2017.051 Downloaded from http://iwaponline.com/ws/article-pdf/17/5/1468/409225/ws017051468.pdf by guest on 21 July 2022