Phylogenetic analysis of Escherichia coli isolates from healthy and diarrhoeic calves in Mashhad, Iran.

Abstract

Escherichia coli is a normal inhabitant of the gastrointestinal tract of vertebrates. Certain Escherichia coli strains have been associated with neonatal diarrhoea in ruminants. These strains can be assigned to one of the four main phylogenetic groups, A, B1, B2 and D. Several studies have shown the relationship between phylogeny and pathogenicity of E. coli, a great deal can be obtained by determining the phylogroup of unknown E. coli strains. In this study, we aimed to evaluate the influence of diarrhoea on the genetic composition of E. coli populations isolated from calves. A total of 80 Escherichia coli isolates were obtained from healthy and diarrhoeic calves. Phylogenetic grouping was done based on the Clermont triplex PCR method using primers targeted at three genetic markers, chuA, yjaA and TspE4.C2. According to our results, phylogenetic group A strains was the most prevalent in both healthy (37.5%) and diarrhoeic calves (55%). Group B1 contained 27.5% of isolates in healthy calves, followed by group B2 (17.5%), and group D (7.5%). Also, four isolates from healthy calves were not included in the major phylogenetic groups or subgroups. A total of 14% and 4% of isolates from diarrhoeic calves beloned to phylogroups B2 and D respectively. Although no isolate from diarrhoeic calves was found to belong to group B1, there was no significant difference between healthy and diarrhoeic calves for other phylogroups. There was not a dramatic shift in E. coli phylogroup/subgroup due to occurrence of diarrhoea in calves, except for phylogroup B1 which was higher in healthy calves. This can be due to the difference in secretions of digestive system in diarrhoeic calves which can prevent the conditions for instability of Escherichia coli isolates of phylogroup B1. The majority of isolates from both healthy and diarrhoeic calves belonged to nonpathogenic phylogentic group A and B1.

Phylogenetic Grouping and Phenotypic Detection of Extended-Spectrum β-Lactamases Among Escherichia coli From Calves and Dairy Cows in Khuzestan, Iran

“…The phylogroup B2 had also the least frequency, both in calves and dairy cows, and these outcomes confirmed the previous investigations. 23 In contrast to a previous study 1 that reported subgroup B2 3 as only present in the human and B2 especially B2 3 as a good index of human fecal pollution, our results showed that subgroup B2 3 was found among isolates from both calves (healthy) and dairy cows. Similarly, another study showed that E. coli isolates of ruminants (sheep, goat, calves, and cattle) and dogs belonged to the subgroup B2 3 .…”

“…These results were almost similar to other studies which demonstrated that the isolates of phylogroup A were prevalent in the intestinal tracts of most animals 24,37 and phylogroup B1 was dominant among isolates from healthy cattle. 38 In accordance with the previous reports in Iran, 23,39 this study showed that the phylogroup B1 was dominant in calves. The phylogroup B2 had also the least frequency, both in calves and dairy cows, and these outcomes confirmed the previous investigations.…”

“…Similarly, another study showed that E. coli isolates of ruminants (sheep, goat, calves, and cattle) and dogs belonged to the subgroup B2 3 . 23,40 Phylogenetic subgroups D2 and A0 and phylogroup B2 were not found among isolates from diarrheic calves and our results were similar to previous researches which showed that phylogenetic subgroups D2 and A0 and phylogroup B1 were not found among isolates from diarrhoeic calves. 23 Though difficult to claim, the geographic variation, ecological conditions, environmental and health statuses play a significant role in E. coli phylogroup dispersion.…”

“…23 Briefly, a few colonies were suspended in 300 μL sterile distilled water and heated at 95°C for 10 minutes. Afterward, they were put on ice for 5 minutes.…”

Correlation of Escherichia coli Strains Isolated from Wild Bird Feces and Human Urinary Tract Infections from Phylogenetic Point of View

“…Thus, the strains belonging to B 1 group cannot be ignored and presence and distribution of such bacteria in feces of wild birds can be a potential hazard for humans that are in contact with them (19). There is much documented evidence showing that extension of E. coli phylogroups and virulence genes are not accidental in different hosts, and frequency of phylogenetic groups in hosts is influenced by some factors including host characteristics and food regimen, the antibiotic pressure in each geographic region, ecological differences, body volume, and climate conditions (20,21). EscobarParamo et al (2006) analyzed E. coli strains from fecal samples of birds, human, and other mammals and observed the significant distribution of phylogroups D and B 1 in birds droplets and A and B 2 in human strains (22).…”