Rapid and sensitive detection of Shigella sonnei in feces by the use of an O-antigen-specific monoclonal antibody in a combined immunomagnetic separation-polymerase chain reaction assay

Reporte técnico -- Universidad de Costa Rica, Instituto de Investigaciones en Salud. 1996. Este documento es privado debido a limitaciones de derechos de autor.OBJECTIVE: The aim of the present work was to develop a rapid, specific and highly sensitive diagnostic method for the detection of Shigella sonnei directly from stool samples. DESIGN AND METHODS: An immunomagnetic separation-polymerase chain reaction (IMS-PCR) combined assay for diagnosis of S. sonnei was developed. For this, a monoclonal antibody (Mab) specific for the O-antigen of S. sonnei was coated to magnetic beads for capture, concentration and separation of S. sonnei from feces. Bacterial DNA, was amplified by the PCR with specific primers. The amplified products were developed by dot blot hybridization with a specific alkaline phosphatase-conjugated probe. RESULTS: The purified MASS MAb reacted specifically with the Plesiomonas shigelloides (the same O-antigen as Shigella sonnei) LPS. The primers were specific for invasive Shigella and enteroinvasive Escherichia coli. Only invasive Shigella sonnei strains gave a positive result in the IMS-PCR assay. The detection limit was 10 to 15 c.f.u. CONCLUSIONS: The availability of IMS-PCR assays provides an improved method for the diagnosis of shigellae directly from feces. The assay is rapid, highly sensitive and specific for the detection of Shigella sonnei directly from stool samples.Universidad de Costa Rica, Instituto de Investigaciones en SaludUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA

Serum Antibody Titres to Shigella Lipopolysaccharides and Invasion Plasmid Antigens in Healthy Costa Rican and Swedish Women

Artículo científico -- Universidad de Costa Rica, Instituto de Investigaciones. 1994. Debido a las políticas de la revista en la que el artículo fue publicado, no es posible distribuir la edición del editor/PDF; no obstante, se adjunta el URL de publicación original.Specific serum antibody titres to defined lipopolysaccharides (LPS) of Shigella spp. and Salmonella serogroup B (BO) and Shigella invasion plasmid antigens (Ipa) were determined by enzyme immunoassays in healthy Costa Rican women from low (n = 34), middle (n = 36) and high (n =19) socioeconomic conditions and from 64 Swedish women. Specific IgG antibody titres were the highest, in particular to the S. flexneri Y LPS, with mean titres of 750 (SD = 360), 690 '380), and 820 (300) for the Low, Middle and High Costa Rican groups respectively. Lower titres were recorded against S. sonneiand S. dysenteriae type 1. Titres against Salmonella LPS were very low ( 0.05). Mean IgG-titres to the Ipa of 330 (150), 220 (170) and 140 (110) were found for the 3 Costa Rican groups, respectively. The IgG and IgM titres to Ipa in serum from the Low group were significantly higher than those of the High group (p 0.05). High IgG anti-Ipa titres were found in 38% from the Low, 19% from the Middle but none in the High group (mean value of the High group +2 SD). The anti-Ipa antibodies in the Costa Rican groups seemed to be a better indicator of Shigella exposure than were anti-LPS antibodies. A good degree of correlation was found between serum and colostrum IgA anti-ipa titres (0.651, p < 0.001), and serum S. flexneri LPS and colostrum IgA anti-S. flexneri LPS antibody titres (0.607, p < 0.001).Universidad de Costa Rica, Instituto de Investigaciones en SaludUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA