Enteroaggregative Escherichia coli (EAEC) causes diarrhea in travelers from industrialized nations to developing countries, children of developing countries, and patients with HIV. Although infection responds to antibiotic therapy, increasing antibiotic resistance and the widespread nature of the infection limit the utility of antibiotics. The development of an EAEC-specific vaccine would be useful in the prevention of travel-associated EAEC diarrhea and in the decrease of EAEC-associated mortality in young children in the US and of developing countries. The first objective of the study is to perform a dose-escalation study of EAEC 042 infectivity in healthy adult volunteers who are high producers of IL-8 and seronegative to EAEC. The study will identify the dose of EAEC 042 needed for future studies on EAEC 042 such as phase I-II EAEC vaccine studies. The second objective of the study is to identify the humoral, secretory, and cellular immune response to EAEC 042 specific antigens that are associated with EAEC infection. Study participants will include 25 healthy volunteers, ages 18-40, from the greater Houston area. Study participants will be assigned to 1 of 4 possible dose levels in groups of 5 volunteers each. Each study group will consist of 4 volunteers receiving EAEC and 1 volunteer receiving a sodium bicarbonate placebo solution. Safety data and results will be reviewed by the safety monitoring committee before beginning the next highest dose group. If a dose results in at least 3 of the 4 infected volunteers of a given group, the next highest dose will not be administered. Instead, the concentration will be repeated for validation of the dose. Healthy volunteers will be screened as outpatients for the presence of the -251 AA SNP genotype in the IL-8 gene promoter. Once a volunteer has been screened and determined to be eligible to participate in the study, the volunteer will sign a consent form and be admitted at the University Clinical Research Unit. The volunteer will ingest a determined concentration of EAEC 042 or placebo and be observed for symptoms of infection. All volunteers will receive therapy with levofloxacin to eradicate the infection either once they develop diarrhea or at Day 5 if they remain asymptomatic. Volunteers will be discharged from the hospital on Day 7+/-1. Saliva, blood, and feces will be collected for secretory, humoral, and cellular immune responses to EAEC. An optional procedure will consist of obtaining jejunal and colonic biopsies prior to challenge (Day -13±2) and Days 4±1 and 24±3 post challenge. Volunteer participation in endoscopy studies will be optional and will not be a requirement for the rest of the study. The primary endpoints of the study include: diarrheal illness after exposure to EAEC, shedding of EAEC after exposure, and IgG and secretory IgA (slgA) seroconversion to EAEC dispersin. The secondary endpoints of the study include: increase in fecal markers of intestinal inflammation including cytokines and lactoferrin and description of the jejunal and colonic immune response to EAEC infection.
Enteroaggregative E. coli (EAEC) is a bacterium that can cause diarrhea. The purposes of this study are to: determine how much EAEC is needed to cause diarrhea in a healthy person, determine if a genetic factor is important in causing diarrhea, and to see how the body's defenses control EAEC. Participants include 25 healthy adults, ages 18-40. Volunteers will be assigned to 1 of 4 dose levels in groups of 5 volunteers each. One volunteer in each group will receive a sodium bicarbonate placebo solution. Volunteers will be admitted to the University Clinical Research Unit for up to 8 days. Volunteers will receive therapy with levofloxacin to treat the infection either once they develop diarrhea or at Day 5 if they remain asymptomatic. Study procedures will include saliva, blood, and fecal sample collection. An optional study procedure will include an intestinal biopsy. Participants will be involved in study related procedures for up to 223 days.