Molecular characterization of diarrheagenic Escherichia coli strains from stools samples and food products in Colombia.

The prevalence of diarrheagenic Escherichia coli in childhood diarrhea and the role of contaminated food products in disease transmission in Colombia are largely unknown. The aim of this study is to identify E. coli pathotypes, including E. coli O157:H7, from 108 stool samples from children with acute diarrhea, 38 meat samples and 38 vegetable samples. Multiplex PCR and Bax Dupont systems were used for E. coli pathotype detection. Eighteen (9.8%) E. coli diarrheagenic pathotypes were detected among all clinical and food product samples tested. Four different pathotypes were identified from clinical samples, including enteroaggregative E. coli, enterotoxigenic E. coli, shiga-toxin producing E. coli, and enteropathogenic E. coli. Food product samples were positive for enteroaggregative and shiga-toxin producing E. coli, suggesting that meat and vegetables may be involved in transmission of these E. coli pathotypes in the community. Most E. coli strains identified belong to the phylogenetic groups A and B1, known to be associated with intestinal rather than extraintestinal E. coli clones. Our data is the first molecular E. coli report that confirms the presence of E. coli pathotypes circulating in Colombia among children with diarrhea and food products for human consumption. Implementation of multiplex PCR technology in Latin America and other countries with limited resources may provide an important epidemiological tool for the surveillance of E. coli pathotypes from clinical isolates as well as from water and food product samples.

Detection of Escherichia coli enteropathogens by multiplex polymerase chain reaction from children's diarrheal stools in two Caribbean-Colombian cities.

Acute diarrheal disease is a leading cause of childhood morbidity and mortality in the developing world and Escherichia coli intestinal pathogens are important causative agents. Information on the epidemiology of E. coli intestinal pathogens and their association with diarrheal disease is limited because no diagnostic testing is available in countries with limited resources. To evaluate the prevalence of E. coli intestinal pathogens in a Caribbean-Colombian region, E. coli clinical isolates from children with diarrhea were analyzed by a recently reported two-reaction multiplex polymerase chain reaction (Gomez-Duarte et al., Diagn Microbiol Infect Dis 2009;63:1-9). The phylogenetic group from all E. coli isolates was also typed by a single-reaction multiplex polymerase chain reaction. We found that among 139 E. coli strains analyzed, 20 (14.4%) corresponded to E. coli diarrheagenic pathotypes. Enterotoxigenic, shiga-toxin-producing, enteroaggregative, diffuse adherent, and enteropathogenic E. coli pathotypes were detected, and most of them belonged to the phylogenetic groups A and B1, known to be associated with intestinal pathogens. This is the first report on the molecular characterization of E. coli diarrheogenic isolates in Colombia and the first report on the potential role of E. coli in childhood diarrhea in this geographic area.

Y chromosomal STR polymorphism in northern Chinese populations.

Y chromosomal STRs show sufficient variability among individduals in a population and a high degree of geographical differentiation, such that their polymorphic character makes them especially suited for population genetic studies. To investígate the polymorphism of a set of 17 Y-STR loci in northern China, we genotyped the 17 Y chromosomal STR loci in a population sample of 377 unrelated males from eight ethnic populations in northern China. We calculated the haplotype frequencies, Rst value and carried out the analysis of molecular variance (AMOVA). We then drew the multidimensional scaling analysis (MDS) plot and phylogenetic tree based on the Rst value. All populations showed a high level of haplotype diversity, with low inter-population variance as measured by an analysis of molecular variance. However, the genetic distances were significant when the eight populations were compared to other populations. By MDS and the phylogenetic tree, we found that the eight populations had a close relationship and Xibo had a northeast origination.

Y Chromosomal STR Polymorphism in Northern Chinese Populations

Y chromosomal STRs show sufficient variability among individduals in a population and a high degree of geographical differentiation, such that their polymorphic character makes them especially suited for population genetic studies. To investígate the polymorphism of a set of 17 Y-STR loci in northern China, we genotyped the 17 Y chromosomal STR loci in a population sample of 377 unrelated males from eight ethnic populations in northern China. We calculated the haplotype frequencies, Rst value and carried out the analysis of molecular variance (AMOVA). We then drew the multidimensional scaling analysis (MDS) plot and phylogenetic tree based on the Rst value. All populations showed a high level of haplotype diversity, with low inter-population variance as measured by an analysis of molecular variance. However, the genetic distances were significant when the eight populations were compared to other populations. By MDS and the phylogenetic tree, we found that the eight populations had a close relationship and Xibo had a northeast origination.