William C. Cray

Comparison of prophylactic tetracycline and clioquinol in a rabbit model of intestinal infection with Vibrio cholerae and Escherichia coli

The ability of tetracycline and clioquinol to prevent intestinal colonization of Vibrio cholerae and Escherichia coli was tested in a rabbit model. In the model 10(10) bacteria are given via oro-gastric tube following intravenous cimetidine and oral sodium bicarbonate and prior to intraperitoneal tincture of opium. Eighteen hours after challenge the rabbits are sacrificed, and the numbers of the challenge strain remaining in the jejunum and ileum are determined. Tetracycline interrupted the intestinal colonization of V. cholerae and E. coli. Clioquinol however, had minimal effect on the colonization process. Our studies demonstrate the efficacy of prophylactic tetracycline but do not support the use of clioquinol to prevent intestinal infection due to these organisms. This rabbit model may also be useful to study the efficacy of other antibiotics against these bacterial infections.

Oral Immunization for Cholera: Mucosal Antitoxic Immunity is Important and can Probably be Safely Achieved

There is now much evidence to support the notions that secretory IgA antibody is the first line of immunologic defense of the intestinal mucosa and that a mucosal IgA response is best stimulated by antigens applied to the mucosal surface. On this basis, it has been argued that immunization against cholera, a superficial mucosal infection, should be given orally with the aim of evoking a protective mucosal IgA response (1). Some progress in this direction has been made using either live avirulent mutants of V. cholerae or nonliving antigens derived from this organism (2,3).