Virulence Characteristics, Serotyping and Phylogenetic Typing of Clinical and Environmental Escherichia coli Isolates

Background: Pathogenic Escherichia coli is responsible for serious diseases; i.e.: Peritonitis, colitis, and urinary tract infections (UTIs) and even cancer, resulting in human morbidity and mortality. Environmental strains are increasingly spreading through food and dairy products, contributing to the pathogenetic burden of E. coli infections. Objectives: This study was performed to compare phylogeny, virulence factors, pathogenicity islands (PAIs), and pathotypes in-between clinical and environmental E. coli isolates. Methods: A total of 105 clinical (72) and environmental (33) E. coli isolates were collected. All isolates were subjected to phylogenetic typing using a new quadruplex polymerase chain reaction (PCR). Wide array of virulence genes (VGs) and PAI markers were assessed for both subtypes, as well as, the distribution of different pathotypes among the phylogenetic groups. Results: Seven phylogenetic groups were detected; clinical isolates were more prevalent in phylogenetic groups B2 (22.2%) and D (23.6%), whereas environmental isolates were in groups A (24.2%) and B1 (60.6%). Majority of VGs were higher in clinical E. coli isolates. Environmental isolates showed higher percentage of some other VGs including; stx2 and hlyA. PAI markers were widespread among both categories, showing high extra-intestinal pathogenic E. coli (ExPEC) PAIs combination in environmental isolates. Enteropathogenic E. coli (EPEC) was the most widespread pathotype in clinical isolates versus enterohemorrhagic E. coli (EHEC) in environmental ones. Conclusions: Escherichia coli pathogenicity armoury was not only confined to clinical isolates, but to environmental ones as well. Therefore, environmental E. coli isolates can serve as reservoirs for transmission of E. coli pathogenicity.