Parenteral immunization with either formalin-fixed whole cells of the fimbriate Bgdl7 strain or purified fimbriae protected against Vibrio cholerae 01 infection in rabbits, independent of biotype and serotype. Parenteral immunization of adult rabbits with purified fimbriae prior to V. cholerae 01 challenge resulted in a reduction of 2 to 3 orders of magnitude in the number of bacteria recovered from the small intestines of immunized rabbits in comparison to non-immunized controls. IgG and IgA antibodies against fimbrillin of V. cholerae 01 were detected in the convalescent sera of patients with cholera; however, little fimbrial antigen was detected in the commercially available cholera vaccines when examined by polyclonal and monoclonal antibodies against fimbriae. These data suggest that fimbrial hemagglutinin is a major adhesin of V. cholerae 01 and that parenteral immunization with fimbriae generates a specific immune response in the gut that may serve as one means of mitigating subsequent V. cholerae 01 gut infection.Key words: Cholera, Fimbriae, Vaccine Cholera is an acute diarrheal disease that is caused by the Gram-negative bacillus Vibrio cholerae 01. V. cholerae 01 infects via uptake of contaminated water and foods and preferentially colonizes the upper small intestine.Fimbriae of V. cholerae 01 consist of cell-associated hemagglutinin that is proposed to be one of the major adhesins mediating the interaction of V. cholerae 01 and human epithelial cells in the small intestine (1). Passive protection tests with anti-mannose-binding hemagglutinin pili antibodies (polyclonal and monoclonal) have been proven effective in protection against experimental cholera caused by El Tor vibrios in infant mouse and in rabbit intestinal loop models (7): but to date, there has been no correlation between serum antibody titers to known antigens purified from V. cholerae 01 and clinical protection. Naturally occurring V. cholerae 01 infection confers longlasting protection against reinfection, but such effective V. cholerae 01 antigens remain to be elucidated.Experimentally infecting rabbits with V. cholerae 01 using the ligated ileal loop test has shown that the bacteria are associated with small intestinal epithelial cells (4,5,8). Therefore, small intestinal infection of rabbits may be used to analyze parameters of immunity that interfere with the persistence of V. cholerae 01 at the intestinal epithelium. As previously reported (2, 3), fimbriate V. cholerae 01 strain of Bgd17 (classical biotype, Inaba serotype) was selectively induced and hydrophobic fimbriae were purified from the fimbriate strain.

Recently isolated Vibrio cholerae and Shigella pecies from 6 countries were examined for their drug sensitivities. The sensitivities of V. cholerae were characterized by a narrow inhibitory concentration ranges without any resistant strain. However, the sensitivities of Shigella species were variable and mostly resistant to tetracycline and ampicillin. Japanese isolates of Shigella species were relatively more sensitive to tetracycline and ampicillin than the isolates from the other countries. Indonesian isolates of Shigella species were relatively more resistant than those of the other countries, even to the new antimicrobials such as ofloxacin and cefdinir, and a highly resistant strain against ofloxacin was found.

Pili were detected using electron microscopy in clinical isolates of fie xneri which had been continuously subcultivated in liquid media. Morphologically, the pili appeared as thin, flexible, cylindrical structures of up to 2-5 pm in length and about 3-5 nm in diameter. Two strains showed mannose-resistant (MR) hemagglutination to fresh fowl erythrocytes (type 4), and one to tannic acid-treated horse erythrocyte (type 3) pili. These pili are novel and different from the mannosesensitive (MS) type 1 pili described by Duguid and Gillies.

A total of 1,234 fecal samples from diarrhea cases were examined for etiological bacterial agents at medical facilities in La Paz and Sucre, Bolivia. Eighty strains of Shigella spp., 39 strains of Salmonella spp., 29 strains of Vibrio cholerae, and 222 strains of enteropathogenic Escherichia coli (139 EPEC, 55 ETEC, 29 EIEC, and 1 EHEC) were isolated. With regard to the serovars of Shigella, S. flexneri 2a, 3a, and lb were predominant. In the case of Salmonella, S. enteritidis was the most common, followed by S. typhi, S. poona, and S. paratyphi B. Out of 29 cholera strains, 25 belonged to biovar El Tor, serovar Ogawa while the remaining 4 were serovar Inaba. Among 55 strains of ETEC serotypes, 5 showed ST producers but none showed LT producers. Likewise, among 55 strains of enterohemorrhagic serotypes, only one strain (0157:H7) produced verocytotoxin (VT 2). The results of drug sensitivity tests revealed the predominance of Shigella, EPEC, and ETEC strains resistant to aminobenzil-penicillin (ABPC) and trimethoprim. Since diarrheal patients in Bolivia are treated mainly with ABPC or sulfamethoxazole/trimethoprim (SXT) and rarely with gentamicin, kanamycin, or other drugs, it is possible that ABPC-and SXT-resistant strains will increase and persist in the near future.

This report describes the presence of type 1 fimbriae on Shigella boydii 5 which agglutinate guinea pig erythrocytes and feature mannose-sensitive adherence.Morphologically, the fimbriae were thin, rigid cylinders 2-5 in length and 3-5 nm in diameter, and the organella retained axial holes. This is the first study to have revealed the existence of type 1 fimbriae on S. boydii.