Characterization of Resistance Against Live-attenuated Diarrhoeagenic E. Coli
Condition: Diarrhea; Gastroenteritis; Bacterial Infections; Escherichia Coli Infections
MeSH terms: Infections; Communicable Diseases; Bacterial Infections; Escherichia coli Infections; Gastroenteritis; Diarrhea
Study type: Interventional

Summary: 
      Although the existing diarrhoeagenic Escherichia coli (E. coli) challenge model is already
      suitable for dietary interventions in its current form, further characterization of the
      working-mechanism of the attenuated strain and further optimization of the study design will
      enable the investigators to better select those ingredients that affect the key
      pathophysiological processes. The aim of the CORAL study is to further characterize and
      increase the discriminative power of the diarrhoeagenic E. coli challenge model.
    

Detailed description: 
      Primary Objective:

      In the CORAL study the investigators want to determine whether increasing the inoculation
      dose of diarrhoeagenic Escherichia coli (E. coli) to 5E10 Colony Forming Units (CFU) (at day
      14) and addition of a second challenge 1E10 CFU (at day 35) will result in an increased
      effect-size and duration of measurable outcomes and in an expansion of the relevant clinical
      and biomarker readouts of the challenge model.

      Secondary Objective:

      By extensive biomarker and transcriptome analysis of blood and fecal samples, the
      investigators aim to explore the working mechanism of the non-toxin producing diarrhoeagenic
      E. coli strain and the kinetics of the host response to this infection. In addition, the
      investigators want to determine whether adding extended fasting and addition of a
      standardized evening meal, prior to the inoculation day, will result in a decreased
      between-subject variation.

      Study design:

      The CORAL study is a parallel 7-weeks intervention study. Subjects will be randomly assigned
      to one of two inoculation dosages of a live attenuated diarrhoeagenic E. coli (n=20 per
      group). Subjects will be instructed to maintain their usual pattern of physical activity and
      their habitual food intake, but to standardize their dietary calcium intake. After a
      standardized evening meal and an overnight fast, subjects will be orally infected with a
      live, but attenuated, diarrhoeagenic E. coli (strain E1392-75-2A; collection NIZO food
      research; dose will be either 1E10 CFU (n=22) or 5E10 CFU (n=22) at study day 14). At study
      day 35, after a standardized evening meal and an overnight fast, all subjects will receive a
      second inoculation of 1E10 CFU of the ETEC vaccine (n=44).

      At various time points before and after both diarrhoeagenic E. coli challenges an online
      diary will be kept to record all food and drinks consumption to assess dietary macronutrient
      intake. Moreover, subjects will report information on stool consistency, frequency and
      severity of symptoms. At various time points before and after both diarrhoeagenic E. coli
      challenges venous blood and (complete) stool samples will be collected. Blood and fecal
      samples are collected to quantify several infection- and immune system markers.

      Study population:

      Healthy male subjects, 18-55 years of age who fulfil all of the inclusion criteria and none
      of the exclusion criteria will participate in the CORAL study.

      Intervention:

      At study day 14 and 35, after a standardized evening meal and an overnight fast, all subjects
      will receive an inoculation of the diarrhoeagenic E. coli (1E10 CFU (n=22) or 5E10 CFU (n=22)
      at study day 14; 1E10 CFU (n=40) at study day 35) Subjects will be instructed to maintain
      their habitual diet, except for their dairy intake. Dairy has a high calcium content and
      contributes significantly to total daily calcium intake. These dietary guidelines will limit
      calcium intake on average to 500 mg/day. From our previous studies, we know that calcium can
      significantly reduce the gastro-intestinal symptoms induced by the E. coli strain.

      Main study parameter:

      1. Percentage of faecal dry weight (% determined by freeze-drying)

      Secondary study parameters:

        1. Total faecal wet weight (faecal weight in g/day)

        2. Time to first diarrhoeal stool (reported by the subjects in the online diary)

        3. Stool consistency (Bristol Stool Scale reported by the subjects in the online diary

        4. Number of stools with Bristol Stool Scale >4 (Bristol Stool Scale reported by the
           subjects in the online diary)

        5. Stool frequency (Stools per day reported by the subjects in the online diary)

        6. Incidence and duration of WHO-defined diarrhoea (Calculated from the Bristol Stool Scale
           and the Stool frequency reported by the subjects in the online diary)

        7. The incidence, duration and severity of Gastro-intestinal symptoms (Gastro-intestinal
           Symptom Rating Scale reported by the subjects in the online diary).

        8. In addition, the study contains an explorative phase consisting of biomarker and
           transcriptome analysis, in order to further explore and identify the mechanism and
           kinetics of the host response to the infection.
    

Intervention name(s): E. coli strain E1392-75-2A
Intervention type(s): Biological
Intervention description(s): At study day 14, after a standardized evening meal and an overnight fast, subjects will receive a single oral dose of the attenuated diarrhoeagenic E. coli strain E1392-75-2A (dose will be either 1E10 CFU (n=22) or 5E10 CFU (n=22)). Oral challenge will occur at 10.00 AM. Under supervision of the project team, subjects will get a NaHCO3 solution (100 ml 2% NaHCO3) to neutralize the gastric acid. After 5 minutes, they get a fruit juice (100 ml) containing the attenuated diarrhoeagenic E. coli strain at the above-mentioned dose. Subjects go home, but are not allowed to drink or eat for 1 hour.
At study day 35, after a standardized evening meal and an overnight fast, all subjects will receive a second inoculation 1E10 CFU of the diarrhoeagenic E. coli.
Other intervention name(s): Escherichia coli; E1392-75-2A
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Basic Science
Keywords: Experimental challenge trial