Phenotypic and genotypic characterization of enterotoxigenic Escherichia coli isolates obtained from international travelers to India and Latin America and pediatric population from USA
Enterotoxigenic Escherichia coli (ETEC) is the most common bacterial cause of diarrheal diseases in children in developing countries and travelers from North America and Europe visiting developing countries. The toxins and colonization factors expressed by ETEC contribute to the virulence and pathogenesis in host. Malnutrition and slow physical and mental development in children and decreased performance at work in travelers have been attributed to ETEC related acute diarrheal diseases. Antibodies to the heat labile enterotoxin of ETEC (LT) and colonization factors (CFs) have shown to prevent diarrheal disease caused due to ETEC. Hence an effective vaccine against ETEC may help in preventing acute diarrheal diseases in children and adults travelers. The heat labile enterotoxin of ETEC (ST) however is not-antigenic and a vaccine against ST producing strains must be directed to CFs of ETEC strains. However the data available on toxin and colonization factors from different parts of the world is limited complicating the development of an effective ETEC vaccine. It has also been reported that ETEC strains expressing the same toxin type and colonization factors may be genetically unrelated. In this study we determined the prevalence of different toxin types and colonization factors from adult travelers to India and Latin America and children from the United States of America using polymerase chain reaction assay. We also analyzed the clonal relatedness of these strains using random amplified polymorphic DNA methods. We found that ST was the most common toxin type among the ETEC strains from India, Latin America and United States. LT producing ETEC strains expressed higher number of colonization factors compared to previous studies and may be pathogenically important. Colonization factors varied from one region to another and over time. CS6 was expressed by ETEC strains from all the regions included in this study. There are genetically distinct clonal groups of ETEC strains both within a region and between different regions. The clonal group, however, do not have specificity for any particular toxin or colonization factor. LT, CS6, CS1, CS2 and CS3 are important to ETEC vaccine development since they occur most frequently among adult and pediatric populations and also in different regions of the world.
Kharat, Vineetkumar, "Phenotypic and genotypic characterization of enterotoxigenic Escherichia coli isolates obtained from international travelers to India and Latin America and pediatric population from USA" (2013). Texas Medical Center Dissertations (via ProQuest). AAI3611634.