Try our beta test site

Dose-Finding Study of CS19 Expressing ETEC Challenge Strains

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified November 2007 by Johns Hopkins Bloomberg School of Public Health.
Recruitment status was:  Recruiting
Naval Medical Research Center
Information provided by:
Johns Hopkins Bloomberg School of Public Health Identifier:
First received: November 26, 2007
Last updated: November 27, 2007
Last verified: November 2007
This will be a strain and dose-finding study in which CS19-ETEC strain WS0115A will be administered at a starting inoculum of 5 x 108 colony forming units (cfu) to 5 subjects as the initial step to establish a human disease model. If an 80% attack rate (AR) for predefined diarrheal disease is achieved without high output diarrhea, the same inoculum will be given to 5 - 10 more subjects for confirmation of AR. If an 80% AR is not achieved, AR and severity of disease will be evaluated to determine if the dose should be increased. The same sequence may be conducted with DS26-1 as necessary. If the WS0115A strain causes high output diarrhea, the dose will be adjusted down and further dose characterization continued. An iterative process will be used to select the optimal strain and dose with each step reviewed and approved by the medical monitor.

Condition Intervention Phase
Travelers' Diarrhea
Other: CS19 expressing ETEC strain
Phase 1

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Screening
Official Title: Strain and Dose-Finding Study of DS26-1 and WS0115A Enterotoxigenic E. Coli (ETEC) Challenge Strains That Express CS19 Fimbriae

Resource links provided by NLM:

Further study details as provided by Johns Hopkins Bloomberg School of Public Health:

Primary Outcome Measures:
  • Develop of diarrhea. [ Time Frame: 120 hours after challenge ]

Secondary Outcome Measures:
  • Development of moderate to severe diarrhea [ Time Frame: 120 hours after challenge ]

Estimated Enrollment: 25
Study Start Date: September 2007
Estimated Study Completion Date: May 2008
Arms Assigned Interventions
Ascending dose finding study in 5-10 subjects per dose; to identify the dose able to give a diarrheal attack rate greater than or equal to 80%.
Other: CS19 expressing ETEC strain
Wild type ETEC strain expressing the colonization faction CS19, and LT and ST enterotoxins.

Detailed Description:

This is a phase 1, open-label, strain and dose-finding study designed to establish a human challenge modelfor CS19-ETEC that causes a > 80% attack rate without causing high output diarrhea. This study design is identical to that of the CS17 challenge model recently completed. Two strains of CS19-ETEC isolated from human diarrheal cases have been identified and characterized. Each clinical isolate was used to generate a cGMP MCB and procedures were established to create a fresh inoculum to administer orally in a sodium bicarbonate solution for challenge. Refer to Section 8 for full details on the isolation and preparation of these strains.

CS19-ETEC strain WS0115A (toxin phenotype of LT+ ST+ and serotype O114:H-) will be the lead strain and will be administered orally to an initial cohort of 5 subjects. This strain was isolated from the stool of a 12-month-old Egyptian girl suffering from watery diarrhea identified during a surveillance study conducted in Abees, Egypt from 1993 to 1995 by investigators at the Naval Medical Research Unit-3 (NAMRU-3), Cairo, Egypt. A negative microbiologic work-up for copathogens (other bacterialenteropathogens, rotavirus, Giardia lamblia, Entamoeba histolytica, and Cryptosporidium) supports that the isolated WS0115A strain was pathogenic in this child. Since this strain has an LT+ST+ toxin phenotype, it is the preferred strain to lead in testing the challenge model, since heterologous protection by bovine milk IgG anti-CsbD against an LT+ST+ phenotype would offer a more robust test of the protection afforded by anti-colonization. The alternate strain, CS-19 ETEC strain DS26-1 (toxin phenotype LT+ST-;serotype O8:H9) was isolated in 1990 at the U.S. Navy Forward Laboratory from a U.S. soldier with diarrhea while on deployment to Saudi Arabia during Operation Desert Shield. A negative microbiologic work-up for copathogens (Salmonella typhi, Vibrio cholerae, Giardia lamblia or Entamoeba histolytica)supports that the isolated DS26-1 strain was pathogenic in this individual. Each clinical isolate was used to generate a cGMP master cell bank and procedures were established to create a fresh inoculum to administer orally in a sodium bicarbonate solution for challenge. Refer to Section 8 for full details on the isolation and preparation of these strains.


Ages Eligible for Study:   18 Years to 45 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  1. Male or female between 18 and 45 years of age, inclusive.
  2. General good health, without significant medical illness, abnormal physical examination findings or clinical laboratory abnormalities as determined by principal investigator (PI) or PI in consultation with the medical monitor and Sponsor.
  3. Demonstrate comprehension of the protocol procedures and knowledge of ETEC illness by passing a written examination (pass grade ≥ 70%)
  4. Willing to participate after informed consent obtained.
  5. Available for entire inpatient portion of study and all outpatient study visits.
  6. Negative serum pregnancy test at screening (initial visit and day -7 to - 3) and a negative urine pregnancy test on the day of admission to the inpatient phase for female subjects of childbearing potential. Females of childbearing potential must agree to use an efficacious hormonal or barrier method of birth control during the study. Alternatively, abstinence alone is acceptable. Female subjects who are unable to bear children must provide supporting documentation (e.g., prior tubal ligation or hysterectomy).

Exclusion Criteria:

  1. Presence of a significant medical condition, (e.g., psychiatric conditions or gastrointestinal disease, such as peptic ulcer, symptoms or evidence of active gastritis or gastroesophageal reflux disease, inflammatory bowel disease, alcohol or illicit drug abuse/dependency), or other laboratory abnormalities which in the opinion of the investigator precludes participation in the study.
  2. Immunosuppressive illness or IgA deficiency (below the normal limits)
  3. Positive serology results for HIV, HBsAg, or HCV antibodies.
  4. Significant abnormalities in screening laboratory hematology, serum chemistry, urinalysis, as determined by PI or PI in consultation with the medical monitor and Sponsor.
  5. Allergy to fluoroquinolones, cotrimoxazole, or ampicillin/penicillin (excluded if allergic to two of three).
  6. Fewer than 3 stools per week or more than 3 stools per day as the usual frequency; loose or liquid stools other than on an occasional basis.
  7. History of diarrhea in the 2 weeks prior to planned inpatient phase.
  8. Regular use of laxatives or any agent that increases gastric pH (regular defined as at least weekly).
  9. Use of antibiotics during the 7 days before bacterial dosing or proton pump inhibitors, H2 blockers, or antacids within 48 hours of dosing.
  10. Travel to countries where ETEC or cholera infection is endemic (most of the developing world) within two years prior to dosing.
  11. History of vaccination for or ingestion of ETEC, cholera, or LT toxin.
  12. Stool culture (collected no more than 1 week prior to admission) positive for ETEC or other bacterial enteric pathogens (Salmonella, Shigella and Campylobacter).
  13. Use of any investigational product within 30 days preceding the receipt of the challenge inoculum, or planned use during the active study period.
  14. Use of any medication known to affect the immune function (e.g., corticosteroids) within 30 days preceding receipt of the challenge inoculum or planned use during the active study period. (Topical and intra-articular steroids will not exclude subjects). MANAGEMENT
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00564863

United States, Maryland
Center for Immunization Research - Johns Hopkins Bloomberg School of Public Health
Baltimore, Maryland, United States, 21205
General Clinical Research Center of the Johns Hopkins Hospital
Baltimore, Maryland, United States, 21287
Sponsors and Collaborators
Johns Hopkins Bloomberg School of Public Health
Naval Medical Research Center
Principal Investigator: Robin McKenzie, M.D. Johns Hopkins Bloomberg School of Public Health
  More Information Identifier: NCT00564863     History of Changes
Other Study ID Numbers: CIR 240  WIRB Approval Number 20071069 
Study First Received: November 26, 2007
Last Updated: November 27, 2007

Keywords provided by Johns Hopkins Bloomberg School of Public Health:

Additional relevant MeSH terms:
Signs and Symptoms, Digestive
Signs and Symptoms processed this record on February 20, 2017