Characteristics of human intestinal Escherichia coli with changing environments

Abstract

To investigate if the characteristics of human intestinal Escherichia coli are changing with the environment of the host, we studied intestinal E. coli from subjects having recently migrated from a temperate to a tropical area. We determined the phylogenetic group, the prevalence of the antibiotic resistance, the presence of integrons and the strain diversity in faecal isolates from 25 subjects originally from metropolitan France and expatriated to French Guyana. These characteristics were compared with those of 25 previously studied Wayampi Amerindian natives of French Guyana and from 25 metropolitan French residents. The three groups of subjects were matched for age and sex, had not taken antibiotics for at least 1 month, nor had been hospitalized within the past year. In all, the characteristics of intestinal E. coli from Expatriates were intermediate between those found in residents from metropolitan France and those found in natives of French Guyana. Prevalence of carriage of resistant Gram-negative bacteria in Expatriates was intermediate between French residents and Wayampi as were the prevalence of integrons in E. coli (12.3% versus 16.3% and 7.8% respectively), and the intra-host diversity of E. coli (2.3 strains/subject versus 1.9 and 3.1, respectively); lastly, in Expatriates, the prevalence of carriage of phylogenetic group B2 strains was lower than in French residents (16% versus 56%, P = 0.005), while carriage of phylogenetic group A strains was lower than in Wayampi (56% versus 88%, P = 0.03). Our results suggest that the composition of the commensal intestinal flora of humans is not static but changes dynamically in response to new environmental conditions.

Cyclomodulins in Urosepsis Strains of Escherichia coli

“…These results are different from those of other studies, which found B2 strains predominant in fecal samples of healthy subjects, notably in industrialized countries (14,16,17,29,42,71). This difference might be explained by the impact of geographic/climatic conditions, dietary factors, and/or the use of antibiotics or host genetic factors on the commensal flora (14,16,62). Hence, phylogroup A, and to a lesser extent phylogroup B1, was significantly more prevalent among fecal strains than among urosepsis strains (37% versus 18% [P, 0.011] and 24% versus 5% [P, Ͻ0.001], respectively).…”

Absence of Escherichia coli Phylogenetic Group B2 Strains in Humans and Domesticated Animals from Jeonnam Province, Republic of Korea

“…Moreover, distributional differences among phylogenetic groups of human E. coli isolates are not static and were shown to change in response to geographic shifts in populations, which typically result in subsequent alterations to diet (49). For example, shifts in E. coli phylogenetic groups were found among 25 humans who expatriated from metropolitan France to French Guyana (50). These data suggest that there is a strong environmental influence on the phylogenetic group distribution of intestinal E. coli isolates in humans.…”

Real-Time PCR for Quantitative Analysis of Human Commensal Escherichia coli Populations Reveals a High Frequency of Subdominant Phylogroups

“…The prevalence of E. coli phylogroups in the stools of humans has been shown to depend on sex, age, year of sampling, country of origin, and diet (1,12,45). In our population and using our approach, phylogroups A and B2 were detected in 74% and 70% of cases, respectively, whereas phylogroups B1 and D were detected less often.…”