Showing papers by "Sumio Shinoda published in 2013"

Protective immunity by oral immunization with heat‐killed Shigella strains in a guinea pig colitis model

Abstract: The protective efficacy of and immune response to heat-killed cells of monovalent and hexavalent mixtures of six serogroups/serotypes of Shigella strains (Shigella dysenteriae 1, Shigella flexneri 2a, S flexneri 3a, S flexneri 6, Shigella boydii 4, and Shigella sonnei) were examined in a guinea pig colitis model A monovalent or hexavalent mixture containing 1 × 107 of each serogroup/serotype of heat-killed Shigella cells was administered orally on Days 0, 7, 14 and 21 On Day 28, the immunized animals were challenged rectally with 1 × 109 live virulent cells of each of the six Shigella serogroups/serotypes In all immunized groups, significant levels of protection were observed after these challenges The serum titers of IgG and IgA against the lipopolysaccharide of each of the six Shigella serogroups/serotypes increased exponential during the course of immunization High IgA titers against the lipopolysaccharide of each of the six Shigella serogroups/serotypes were also observed in intestinal lavage fluid from all immunized animals These data indicate that a hexavalent mixture of heat-killed cells of the six Shigella serogroups/serotypes studied would be a possible broad-spectrum candidate vaccine against shigellosis

Inflammatory diarrhea due to enteroaggregative Escherichia coli : evidence from clinical and mice model studies

Abstract: This study was conducted to determine the role of enteroaggregative Escherichia coli (EAEC) in inflammatory diarrhea among hospitalized patients in Kolkata. The inflammatory pathogenesis of EAEC was established in mice model and histopathological studies. Presence of fecal leucocytes (FLCs) can be suspected for EAEC infection solely or as a mixed with other enteric pathogens. Active surveillance was conducted for 2 years on 2 random days per week with every 5th patient admitted to the Infectious Diseases Hospital (IDH). Diarrheal samples were processed by conventional culture, microscopy, ELISA and molecular methods. Two EAEC isolated as sole pathogens were examined in mice after induced intestinal infection. The intestinal tissue samples were processed to analyze the histological changes. Of the 2519 samples screened, fecal leucocytes, erythrocytes and occult blood were detected in 1629 samples. Most of the patients had acute watery diarrhea (75%) and vomiting (78%). Vibrio cholerae O1 was the main pathogen in patients of 5–10 years age group (33%). Shigellosis was more in children from 2–5 years of age (19%), whereas children <2 years appeared to be susceptible for infection caused by EAEC (16%). When tested for the pathogenicity, the EAEC strains colonized well and caused inflammatory infection in the gut mucosa of BALB/C mice. This hospital-based surveillance revealed prevalence of large number of inflammatory diarrhea. EAEC was the suspected pathogen and <2 years children appeared to be the most susceptible age group. BALB/C mice may be a suitable animal model to study the EAEC-mediated pathogenesis.

Ecological Study of Pathogenic Vibrios in Aquatic Environments

Abstract: An ecological study of pathogenic vibrios in aquatic environments of Okayama was carried out. The number of Vibrio parahaemolyticus detected in the sea area was comparatively smaler than that found in the survey of about two decades ago. Various reasons for the decrease in the case of food poisoning by V. parahaemolyticus have been suggested but the lower number of the vibrio in aquatic environments may be one explanation. Although the number of V. vulnificus was also not as large, most of the isolates possessed the pathogenic genes, vvp and vvh, suggesting the potential for fatal pathogenicity to patients having underlying diseases. As for V. cholerae, some non-O1/non-O139 serovar isolates were detected in a fresh water area, and many of them had hlyA, the gene for hemolysin which acts as a pathogenic factor in sporadic cases of diarrhea. Thus, the total number of pathogenic vibrios detected was not of concern. However, the marine products of these areas are shipped in wide area and are for general consumption. Therefore, it is necessary to continue to survey pathogenic vibrios in aquatic environments in order to ensure food hygiene.